<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2021 Workiva-->
<!--r:89db5cb2-2d64-4049-9c12-b9b633e3f1fb,g:74baeb0f-e929-4406-8980-c5f971dac0e1-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/ConsolidatedStatementsofOperations" xlink:type="simple" xlink:href="aqunf-20210630.xsd#ConsolidatedStatementsofOperations"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/ConsolidatedStatementsofOperations" xlink:type="extended" id="ic52e1a5208024fcf86c427600e2b0b17_ConsolidatedStatementsofOperations">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_8402085f-96f8-4fb4-8cd0-517b81c9b707" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_us-gaap_RevenuesAbstract_8402085f-96f8-4fb4-8cd0-517b81c9b707" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_41fe98e3-1299-4707-8cae-dece79b125b8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_8402085f-96f8-4fb4-8cd0-517b81c9b707" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_41fe98e3-1299-4707-8cae-dece79b125b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpensesAbstract_d0ca167d-8a33-4ec3-b152-a45ec69ab22b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CostsAndExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_us-gaap_CostsAndExpensesAbstract_d0ca167d-8a33-4ec3-b152-a45ec69ab22b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_c9143d27-f361-4a35-a1bb-cee4bd7a3e5b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_d0ca167d-8a33-4ec3-b152-a45ec69ab22b" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_c9143d27-f361-4a35-a1bb-cee4bd7a3e5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_d4e223c3-c0d9-4c34-be90-bd6f319c86a5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_d0ca167d-8a33-4ec3-b152-a45ec69ab22b" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_d4e223c3-c0d9-4c34-be90-bd6f319c86a5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_8d611968-1a3c-4041-8d51-1169abe58155" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_d0ca167d-8a33-4ec3-b152-a45ec69ab22b" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_8d611968-1a3c-4041-8d51-1169abe58155" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_47ceadbf-5204-41b7-a800-60062586b22f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_d0ca167d-8a33-4ec3-b152-a45ec69ab22b" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_47ceadbf-5204-41b7-a800-60062586b22f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_65cac643-70b8-4c2a-a3b9-63987d561487" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_d0ca167d-8a33-4ec3-b152-a45ec69ab22b" xlink:to="loc_us-gaap_CostsAndExpenses_65cac643-70b8-4c2a-a3b9-63987d561487" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_c9affda9-d7e3-4cf3-8ff9-6c5fa36a515e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_us-gaap_OperatingIncomeLoss_c9affda9-d7e3-4cf3-8ff9-6c5fa36a515e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseOtherLongTermDebt_b91d5b09-4562-4d1d-9eae-7cd97e20c27f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestExpenseOtherLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_us-gaap_InterestExpenseOtherLongTermDebt_b91d5b09-4562-4d1d-9eae-7cd97e20c27f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnInvestments_847f1555-1fba-487b-aed2-c8e1b9a3852f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainLossOnInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_us-gaap_GainLossOnInvestments_847f1555-1fba-487b-aed2-c8e1b9a3852f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingExpense_665082c4-60fd-4bf3-81f3-3d79411a1bb3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherNonoperatingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_us-gaap_OtherNonoperatingExpense_665082c4-60fd-4bf3-81f3-3d79411a1bb3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DefinedBenefitPlanNonserviceCostsTotal_7b7fa825-aada-47ff-a07e-a8e6a6b9c87b" xlink:href="aqunf-20210630.xsd#aqunf_DefinedBenefitPlanNonserviceCostsTotal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_aqunf_DefinedBenefitPlanNonserviceCostsTotal_7b7fa825-aada-47ff-a07e-a8e6a6b9c87b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnOilAndGasHedgingActivity_bd55470d-7596-4fd0-b607-3e9d36646874" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainLossOnOilAndGasHedgingActivity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_us-gaap_GainLossOnOilAndGasHedgingActivity_bd55470d-7596-4fd0-b607-3e9d36646874" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_abc97f64-ef2e-4300-80f9-14ea5cdeab48" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_abc97f64-ef2e-4300-80f9-14ea5cdeab48" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract_887e1ad0-2aff-4478-82a8-08d785c1c3a9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract_887e1ad0-2aff-4478-82a8-08d785c1c3a9" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_f303e95b-dd1b-4131-a7ae-f2d1e575a3dd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract_887e1ad0-2aff-4478-82a8-08d785c1c3a9" xlink:to="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_f303e95b-dd1b-4131-a7ae-f2d1e575a3dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_aab48f77-2f99-4c21-944c-3eb8d94f7b5f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract_887e1ad0-2aff-4478-82a8-08d785c1c3a9" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_aab48f77-2f99-4c21-944c-3eb8d94f7b5f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_f6c60cf9-37b6-4432-8b09-540d8915e841" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract_887e1ad0-2aff-4478-82a8-08d785c1c3a9" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_f6c60cf9-37b6-4432-8b09-540d8915e841" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_4d5b2367-bfde-49ff-b491-1d86d1badd39" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_us-gaap_ProfitLoss_4d5b2367-bfde-49ff-b491-1d86d1badd39" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_d89b9cb9-c848-486b-9362-68b3c27ca5a0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_d89b9cb9-c848-486b-9362-68b3c27ca5a0" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NetIncomeLossAttributabletoNoncontrollingInterestHeldByRelatedParty_eb518f58-1f59-49be-b99f-a65be525a7f9" xlink:href="aqunf-20210630.xsd#aqunf_NetIncomeLossAttributabletoNoncontrollingInterestHeldByRelatedParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_aqunf_NetIncomeLossAttributabletoNoncontrollingInterestHeldByRelatedParty_eb518f58-1f59-49be-b99f-a65be525a7f9" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NetIncomeLossAttributableToNoncontrollingInterestNetOfRelatedParty_1157b693-5b25-49b0-972d-d34558b89769" xlink:href="aqunf-20210630.xsd#aqunf_NetIncomeLossAttributableToNoncontrollingInterestNetOfRelatedParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_aqunf_NetIncomeLossAttributableToNoncontrollingInterestNetOfRelatedParty_1157b693-5b25-49b0-972d-d34558b89769" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_da0b9446-58ce-4de0-b335-5ddf3bb12790" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_us-gaap_NetIncomeLoss_da0b9446-58ce-4de0-b335-5ddf3bb12790" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendsIncomeStatementImpact_aacab0a4-fbb6-429b-bb57-03cb4bc82cda" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PreferredStockDividendsIncomeStatementImpact"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_us-gaap_PreferredStockDividendsIncomeStatementImpact_aacab0a4-fbb6-429b-bb57-03cb4bc82cda" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NetIncomeLossAttributableToCommonStockHoldersBasicAndDiluted_00d9bffc-5a59-44c8-987f-e4974e6538dc" xlink:href="aqunf-20210630.xsd#aqunf_NetIncomeLossAttributableToCommonStockHoldersBasicAndDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_aqunf_NetIncomeLossAttributableToCommonStockHoldersBasicAndDiluted_00d9bffc-5a59-44c8-987f-e4974e6538dc" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract_ab25619d-81c5-426e-b396-420e07d0109d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_us-gaap_EarningsPerShareAbstract_ab25619d-81c5-426e-b396-420e07d0109d" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_cedc4cf3-f08c-44e7-97ce-e58fe844a77e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_ab25619d-81c5-426e-b396-420e07d0109d" xlink:to="loc_us-gaap_EarningsPerShareBasic_cedc4cf3-f08c-44e7-97ce-e58fe844a77e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_35060a79-4ba9-4455-ae9b-fb00837a0f81" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_ab25619d-81c5-426e-b396-420e07d0109d" xlink:to="loc_us-gaap_EarningsPerShareDiluted_35060a79-4ba9-4455-ae9b-fb00837a0f81" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_9e606ec6-1f45-4362-97ef-106d41cc8a3f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_eb7b333e-214c-4595-ad6e-e38bec9f4fa8" xlink:to="loc_us-gaap_StatementTable_9e606ec6-1f45-4362-97ef-106d41cc8a3f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_a7e0980a-69fc-4c1e-a516-797cbf5b1733" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_9e606ec6-1f45-4362-97ef-106d41cc8a3f" xlink:to="loc_srt_ProductOrServiceAxis_a7e0980a-69fc-4c1e-a516-797cbf5b1733" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_a7e0980a-69fc-4c1e-a516-797cbf5b1733_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_a7e0980a-69fc-4c1e-a516-797cbf5b1733" xlink:to="loc_srt_ProductsAndServicesDomain_a7e0980a-69fc-4c1e-a516-797cbf5b1733_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_d1e412ad-7822-4f5e-b887-e79be53cb6d6" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_a7e0980a-69fc-4c1e-a516-797cbf5b1733" xlink:to="loc_srt_ProductsAndServicesDomain_d1e412ad-7822-4f5e-b887-e79be53cb6d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_RegulatedElectricityMember_bd143210-5750-4bf6-86b6-368ed36cc5b1" xlink:href="aqunf-20210630.xsd#aqunf_RegulatedElectricityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d1e412ad-7822-4f5e-b887-e79be53cb6d6" xlink:to="loc_aqunf_RegulatedElectricityMember_bd143210-5750-4bf6-86b6-368ed36cc5b1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_RegulatedGasMember_bb9bc82a-cfbc-4f0d-8f64-aaa4494e56b9" xlink:href="aqunf-20210630.xsd#aqunf_RegulatedGasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d1e412ad-7822-4f5e-b887-e79be53cb6d6" xlink:to="loc_aqunf_RegulatedGasMember_bb9bc82a-cfbc-4f0d-8f64-aaa4494e56b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_RegulatedWaterMember_fbc5123d-75ea-4d4d-a197-ad9a8a134ead" xlink:href="aqunf-20210630.xsd#aqunf_RegulatedWaterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d1e412ad-7822-4f5e-b887-e79be53cb6d6" xlink:to="loc_aqunf_RegulatedWaterMember_fbc5123d-75ea-4d4d-a197-ad9a8a134ead" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NonRegulatedEnergyMember_59883569-159e-4226-9660-4609bc14ba22" xlink:href="aqunf-20210630.xsd#aqunf_NonRegulatedEnergyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d1e412ad-7822-4f5e-b887-e79be53cb6d6" xlink:to="loc_aqunf_NonRegulatedEnergyMember_59883569-159e-4226-9660-4609bc14ba22" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_OtherRevenueMember_621c35aa-184f-4d10-8aec-a4e831dffc5b" xlink:href="aqunf-20210630.xsd#aqunf_OtherRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d1e412ad-7822-4f5e-b887-e79be53cb6d6" xlink:to="loc_aqunf_OtherRevenueMember_621c35aa-184f-4d10-8aec-a4e831dffc5b" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/ConsolidatedStatementofEquity" xlink:type="simple" xlink:href="aqunf-20210630.xsd#ConsolidatedStatementofEquity"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/ConsolidatedStatementofEquity" xlink:type="extended" id="i50c3f1658e314afba24af2d555ad876a_ConsolidatedStatementofEquity">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_5af569bd-aa61-4470-9d99-d8cf9c44ec2d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_37641d59-7cf5-4926-94ff-e172a3902e0f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_5af569bd-aa61-4470-9d99-d8cf9c44ec2d" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_37641d59-7cf5-4926-94ff-e172a3902e0f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_3d8559ee-41c7-45d0-8ce5-4f8c4a544161" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_37641d59-7cf5-4926-94ff-e172a3902e0f" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_3d8559ee-41c7-45d0-8ce5-4f8c4a544161" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_a27cadf4-f84a-4faf-a646-a38f8c5066ba" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_37641d59-7cf5-4926-94ff-e172a3902e0f" xlink:to="loc_us-gaap_ProfitLoss_a27cadf4-f84a-4faf-a646-a38f8c5066ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationsOfTemporaryToPermanentEquity_8cf39881-e6e0-43e2-be10-9436b7c2a9df" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReclassificationsOfTemporaryToPermanentEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_37641d59-7cf5-4926-94ff-e172a3902e0f" xlink:to="loc_us-gaap_ReclassificationsOfTemporaryToPermanentEquity_8cf39881-e6e0-43e2-be10-9436b7c2a9df" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_d72eb7f7-2b7c-4add-aece-4c1c2228a0d1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_37641d59-7cf5-4926-94ff-e172a3902e0f" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_d72eb7f7-2b7c-4add-aece-4c1c2228a0d1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DividendsandDistributionstoNoncontrollingInterests_9434c952-7bdf-4b99-af0d-d99a1ba7fb33" xlink:href="aqunf-20210630.xsd#aqunf_DividendsandDistributionstoNoncontrollingInterests"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_37641d59-7cf5-4926-94ff-e172a3902e0f" xlink:to="loc_aqunf_DividendsandDistributionstoNoncontrollingInterests_9434c952-7bdf-4b99-af0d-d99a1ba7fb33" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueDividendReinvestmentPlan_46ba2516-23e6-46bf-a866-bbddd4c141d5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueDividendReinvestmentPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_37641d59-7cf5-4926-94ff-e172a3902e0f" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueDividendReinvestmentPlan_46ba2516-23e6-46bf-a866-bbddd4c141d5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance_a4f1e069-d788-47dd-8701-94c1a6398e35" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_37641d59-7cf5-4926-94ff-e172a3902e0f" xlink:to="loc_us-gaap_NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance_a4f1e069-d788-47dd-8701-94c1a6398e35" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_StockIssuedDuringPeriodValueConversionofSubscriptionReceipts_0ceaedf6-f0d6-4cee-a784-eebeb80f4d18" xlink:href="aqunf-20210630.xsd#aqunf_StockIssuedDuringPeriodValueConversionofSubscriptionReceipts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_37641d59-7cf5-4926-94ff-e172a3902e0f" xlink:to="loc_aqunf_StockIssuedDuringPeriodValueConversionofSubscriptionReceipts_0ceaedf6-f0d6-4cee-a784-eebeb80f4d18" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_2b48349c-3da2-49dc-b049-1f3e5a2ccf9c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_37641d59-7cf5-4926-94ff-e172a3902e0f" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_2b48349c-3da2-49dc-b049-1f3e5a2ccf9c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AdjustmentsToAdditionalPaidInCapitalContractAdjustmentPayments_26b39815-b6e9-4d7c-bb67-9d6c1074e947" xlink:href="aqunf-20210630.xsd#aqunf_AdjustmentsToAdditionalPaidInCapitalContractAdjustmentPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_37641d59-7cf5-4926-94ff-e172a3902e0f" xlink:to="loc_aqunf_AdjustmentsToAdditionalPaidInCapitalContractAdjustmentPayments_26b39815-b6e9-4d7c-bb67-9d6c1074e947" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_da8ae5b4-13cc-41d7-8a7a-6641c28a8d3d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_37641d59-7cf5-4926-94ff-e172a3902e0f" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_da8ae5b4-13cc-41d7-8a7a-6641c28a8d3d" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_655e3aac-1d0b-44ab-ab12-12848595be1f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_37641d59-7cf5-4926-94ff-e172a3902e0f" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_655e3aac-1d0b-44ab-ab12-12848595be1f" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_2cb62c36-1645-47fa-9cfc-f5e798982940" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_37641d59-7cf5-4926-94ff-e172a3902e0f" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_2cb62c36-1645-47fa-9cfc-f5e798982940" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination_f58e512d-a61f-416a-94e3-e26fe297e613" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_37641d59-7cf5-4926-94ff-e172a3902e0f" xlink:to="loc_us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination_f58e512d-a61f-416a-94e3-e26fe297e613" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_bdf300e0-4135-4f87-a685-8a453ed008e3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_a0d1735b-2a5f-4ce1-8875-7321c836c77c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_5af569bd-aa61-4470-9d99-d8cf9c44ec2d" xlink:to="loc_us-gaap_StatementTable_a0d1735b-2a5f-4ce1-8875-7321c836c77c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_785001b4-f167-4300-9896-39f9871470f7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_a0d1735b-2a5f-4ce1-8875-7321c836c77c" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_785001b4-f167-4300-9896-39f9871470f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_785001b4-f167-4300-9896-39f9871470f7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_785001b4-f167-4300-9896-39f9871470f7" xlink:to="loc_us-gaap_EquityComponentDomain_785001b4-f167-4300-9896-39f9871470f7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_6a9d1ce0-313b-4918-83e3-23ec4d1a822a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_785001b4-f167-4300-9896-39f9871470f7" xlink:to="loc_us-gaap_EquityComponentDomain_6a9d1ce0-313b-4918-83e3-23ec4d1a822a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_2905b346-d012-4b5b-95d1-661f211b8704" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6a9d1ce0-313b-4918-83e3-23ec4d1a822a" xlink:to="loc_us-gaap_CommonStockMember_2905b346-d012-4b5b-95d1-661f211b8704" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockMember_441eb832-3120-49f7-94f2-86de083b40d9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6a9d1ce0-313b-4918-83e3-23ec4d1a822a" xlink:to="loc_us-gaap_PreferredStockMember_441eb832-3120-49f7-94f2-86de083b40d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_f4c15a6d-8dfd-48c6-9ae5-cb6f50694fe7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6a9d1ce0-313b-4918-83e3-23ec4d1a822a" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_f4c15a6d-8dfd-48c6-9ae5-cb6f50694fe7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_57821baf-7103-4c65-bc4e-4527420f51a1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6a9d1ce0-313b-4918-83e3-23ec4d1a822a" xlink:to="loc_us-gaap_RetainedEarningsMember_57821baf-7103-4c65-bc4e-4527420f51a1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_9de2ff53-beb6-48c4-8ede-cf94d9a837bc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6a9d1ce0-313b-4918-83e3-23ec4d1a822a" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_9de2ff53-beb6-48c4-8ede-cf94d9a837bc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_77f57593-6b7c-464b-909e-cfeaccba42dd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_6a9d1ce0-313b-4918-83e3-23ec4d1a822a" xlink:to="loc_us-gaap_NoncontrollingInterestMember_77f57593-6b7c-464b-909e-cfeaccba42dd" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/ConsolidatedStatementsofCashFlows" xlink:type="simple" xlink:href="aqunf-20210630.xsd#ConsolidatedStatementsofCashFlows"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/ConsolidatedStatementsofCashFlows" xlink:type="extended" id="iea06d261a0e8486c811b5d3e8fcb0e7d_ConsolidatedStatementsofCashFlows">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_eaf9753c-841a-44a8-a42b-9eeb3d4b6df4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseAbstract_9b0103a0-5076-4bda-95ec-916f30a198af" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eaf9753c-841a-44a8-a42b-9eeb3d4b6df4" xlink:to="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseAbstract_9b0103a0-5076-4bda-95ec-916f30a198af" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_2a744bed-54f9-4716-b525-af4dea84ca4a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseAbstract_9b0103a0-5076-4bda-95ec-916f30a198af" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_2a744bed-54f9-4716-b525-af4dea84ca4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_2c92e8c6-1a6e-4c9f-91c7-ef8352d72df5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_2a744bed-54f9-4716-b525-af4dea84ca4a" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_2c92e8c6-1a6e-4c9f-91c7-ef8352d72df5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_330d8575-ef57-438e-b84a-628503355a82" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_2a744bed-54f9-4716-b525-af4dea84ca4a" xlink:to="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_330d8575-ef57-438e-b84a-628503355a82" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DepreciationandAmortizationofOtherExpense_274d0806-216b-4ba1-aa77-7cccf9bc8ced" xlink:href="aqunf-20210630.xsd#aqunf_DepreciationandAmortizationofOtherExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_330d8575-ef57-438e-b84a-628503355a82" xlink:to="loc_aqunf_DepreciationandAmortizationofOtherExpense_274d0806-216b-4ba1-aa77-7cccf9bc8ced" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_11912ca0-d035-4e7c-ae6f-f7631c83631e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_330d8575-ef57-438e-b84a-628503355a82" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_11912ca0-d035-4e7c-ae6f-f7631c83631e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnDerivatives_45a31448-22d6-489a-843d-758d46345d37" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnrealizedGainLossOnDerivatives"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_330d8575-ef57-438e-b84a-628503355a82" xlink:to="loc_us-gaap_UnrealizedGainLossOnDerivatives_45a31448-22d6-489a-843d-758d46345d37" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_bdf0159d-51f2-4f44-bdf5-038c1a3945d5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_330d8575-ef57-438e-b84a-628503355a82" xlink:to="loc_us-gaap_ShareBasedCompensation_bdf0159d-51f2-4f44-bdf5-038c1a3945d5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions_d6196431-b1f6-4160-b4d6-34b2634ef6ef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_330d8575-ef57-438e-b84a-628503355a82" xlink:to="loc_us-gaap_PublicUtilitiesAllowanceForFundsUsedDuringConstructionAdditions_d6196431-b1f6-4160-b4d6-34b2634ef6ef" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnInvestments_ced63ef8-d9b5-4490-b5b6-3e27d7908b4e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnrealizedGainLossOnInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_330d8575-ef57-438e-b84a-628503355a82" xlink:to="loc_us-gaap_UnrealizedGainLossOnInvestments_ced63ef8-d9b5-4490-b5b6-3e27d7908b4e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncashIncomeExpense_a614bad4-ef5b-4ee6-95a5-4208a6d6768b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherNoncashIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_330d8575-ef57-438e-b84a-628503355a82" xlink:to="loc_us-gaap_OtherNoncashIncomeExpense_a614bad4-ef5b-4ee6-95a5-4208a6d6768b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentDividendsOrDistributions_b5bfee41-c360-4b7c-ba6c-f90e3894e66d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityMethodInvestmentDividendsOrDistributions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_330d8575-ef57-438e-b84a-628503355a82" xlink:to="loc_us-gaap_EquityMethodInvestmentDividendsOrDistributions_b5bfee41-c360-4b7c-ba6c-f90e3894e66d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_242728dd-17c3-4d03-b5de-4e65885e769c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherOperatingActivitiesCashFlowStatement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_330d8575-ef57-438e-b84a-628503355a82" xlink:to="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_242728dd-17c3-4d03-b5de-4e65885e769c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_IncreaseDecreaseinOperatingCapitalContinuingOperations_91898862-c0f4-43af-aaf8-33e7eb73a843" xlink:href="aqunf-20210630.xsd#aqunf_IncreaseDecreaseinOperatingCapitalContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_2a744bed-54f9-4716-b525-af4dea84ca4a" xlink:to="loc_aqunf_IncreaseDecreaseinOperatingCapitalContinuingOperations_91898862-c0f4-43af-aaf8-33e7eb73a843" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_425c3392-72cd-4a62-b9df-3c26bad9d9a7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_2a744bed-54f9-4716-b525-af4dea84ca4a" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_425c3392-72cd-4a62-b9df-3c26bad9d9a7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1b8f8412-af15-44b8-9ff7-3b0d69d9e772" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseAbstract_9b0103a0-5076-4bda-95ec-916f30a198af" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1b8f8412-af15-44b8-9ff7-3b0d69d9e772" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_686c86de-5d47-425c-b6a3-496e57cc1c26" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1b8f8412-af15-44b8-9ff7-3b0d69d9e772" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_686c86de-5d47-425c-b6a3-496e57cc1c26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_eb704c37-2249-492b-aff1-525bd986a1b8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1b8f8412-af15-44b8-9ff7-3b0d69d9e772" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_eb704c37-2249-492b-aff1-525bd986a1b8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ProceedsfromIssuanceofCommonStockNetofStockIssuanceCosts_0f5aa214-f8fa-470a-b553-bae66c4de324" xlink:href="aqunf-20210630.xsd#aqunf_ProceedsfromIssuanceofCommonStockNetofStockIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1b8f8412-af15-44b8-9ff7-3b0d69d9e772" xlink:to="loc_aqunf_ProceedsfromIssuanceofCommonStockNetofStockIssuanceCosts_0f5aa214-f8fa-470a-b553-bae66c4de324" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividendsCommonStock_9b83a8a1-8b6f-4548-9a2f-5b733ab04d2d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsOfDividendsCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1b8f8412-af15-44b8-9ff7-3b0d69d9e772" xlink:to="loc_us-gaap_PaymentsOfDividendsCommonStock_9b83a8a1-8b6f-4548-9a2f-5b733ab04d2d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock_98cdb6e3-8b15-491b-8c26-ec7a3751d0d5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1b8f8412-af15-44b8-9ff7-3b0d69d9e772" xlink:to="loc_us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock_98cdb6e3-8b15-491b-8c26-ec7a3751d0d5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromMinorityShareholders_a52d72ed-5ac7-4ec1-a806-b4a56b5eb721" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromMinorityShareholders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1b8f8412-af15-44b8-9ff7-3b0d69d9e772" xlink:to="loc_us-gaap_ProceedsFromMinorityShareholders_a52d72ed-5ac7-4ec1-a806-b4a56b5eb721" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ProceedsfromNoncontrollingInterestsProductionBased_2c836030-244e-485b-a0f8-9c36b5e4e1cf" xlink:href="aqunf-20210630.xsd#aqunf_ProceedsfromNoncontrollingInterestsProductionBased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1b8f8412-af15-44b8-9ff7-3b0d69d9e772" xlink:to="loc_aqunf_ProceedsfromNoncontrollingInterestsProductionBased_2c836030-244e-485b-a0f8-9c36b5e4e1cf" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_PaymentstoNoncontrollingInterestsRelatedParty_6789a460-386c-4e74-95d7-63c54a622e92" xlink:href="aqunf-20210630.xsd#aqunf_PaymentstoNoncontrollingInterestsRelatedParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1b8f8412-af15-44b8-9ff7-3b0d69d9e772" xlink:to="loc_aqunf_PaymentstoNoncontrollingInterestsRelatedParty_6789a460-386c-4e74-95d7-63c54a622e92" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToMinorityShareholders_1def659e-422b-4aa6-8906-25544d1a3d2f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToMinorityShareholders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1b8f8412-af15-44b8-9ff7-3b0d69d9e772" xlink:to="loc_us-gaap_PaymentsToMinorityShareholders_1def659e-422b-4aa6-8906-25544d1a3d2f" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForDerivativeInstrumentFinancingActivities_3aa1181a-6588-4677-b37c-55980fb8732a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsForDerivativeInstrumentFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1b8f8412-af15-44b8-9ff7-3b0d69d9e772" xlink:to="loc_us-gaap_PaymentsForDerivativeInstrumentFinancingActivities_3aa1181a-6588-4677-b37c-55980fb8732a" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_98285226-9f41-4922-80fc-bb46898160f3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1b8f8412-af15-44b8-9ff7-3b0d69d9e772" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_98285226-9f41-4922-80fc-bb46898160f3" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_00c7126a-01fc-4b38-9d3a-627f6c9fb231" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1b8f8412-af15-44b8-9ff7-3b0d69d9e772" xlink:to="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_00c7126a-01fc-4b38-9d3a-627f6c9fb231" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromRepaymentsOfOtherLongTermDebt_3cd52132-5d1d-4edb-ab2e-d1acd6dd2478" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromRepaymentsOfOtherLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1b8f8412-af15-44b8-9ff7-3b0d69d9e772" xlink:to="loc_us-gaap_ProceedsFromRepaymentsOfOtherLongTermDebt_3cd52132-5d1d-4edb-ab2e-d1acd6dd2478" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_72108732-d0e2-4bca-8016-2fe082c08a2c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_1b8f8412-af15-44b8-9ff7-3b0d69d9e772" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_72108732-d0e2-4bca-8016-2fe082c08a2c" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_a0e0649f-4efa-4486-9c67-cc5a2e4f92dc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseAbstract_9b0103a0-5076-4bda-95ec-916f30a198af" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_a0e0649f-4efa-4486-9c67-cc5a2e4f92dc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireProductiveAssets_42d60075-20cf-45e1-9e23-681064bd3f59" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToAcquireProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_a0e0649f-4efa-4486-9c67-cc5a2e4f92dc" xlink:to="loc_us-gaap_PaymentsToAcquireProductiveAssets_42d60075-20cf-45e1-9e23-681064bd3f59" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireLongtermInvestments_ffe50bd9-7a83-4dfc-be7c-55bea166afcc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToAcquireLongtermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_a0e0649f-4efa-4486-9c67-cc5a2e4f92dc" xlink:to="loc_us-gaap_PaymentsToAcquireLongtermInvestments_ffe50bd9-7a83-4dfc-be7c-55bea166afcc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_02dda098-08f8-4b9f-88ef-1a9e282ea3ab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_a0e0649f-4efa-4486-9c67-cc5a2e4f92dc" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_02dda098-08f8-4b9f-88ef-1a9e282ea3ab" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_PaymentstoAcquireOtherAssets.InvestingActivities_324e3294-2195-4f1b-8ccd-2117f4e1d13c" xlink:href="aqunf-20210630.xsd#aqunf_PaymentstoAcquireOtherAssets.InvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_a0e0649f-4efa-4486-9c67-cc5a2e4f92dc" xlink:to="loc_aqunf_PaymentstoAcquireOtherAssets.InvestingActivities_324e3294-2195-4f1b-8ccd-2117f4e1d13c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ProceedsfromCollectionofPrincipalonDevelopmentLoansReceivable_9d728fc0-b21b-4bb4-a3ed-c9eae2271d8e" xlink:href="aqunf-20210630.xsd#aqunf_ProceedsfromCollectionofPrincipalonDevelopmentLoansReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_a0e0649f-4efa-4486-9c67-cc5a2e4f92dc" xlink:to="loc_aqunf_ProceedsfromCollectionofPrincipalonDevelopmentLoansReceivable_9d728fc0-b21b-4bb4-a3ed-c9eae2271d8e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_5ff2a9cd-9bb1-4152-8bef-e46032bde885" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_a0e0649f-4efa-4486-9c67-cc5a2e4f92dc" xlink:to="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_5ff2a9cd-9bb1-4152-8bef-e46032bde885" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_a43746a7-9d25-4454-a0b1-79f7aeefaeba" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_a0e0649f-4efa-4486-9c67-cc5a2e4f92dc" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_a43746a7-9d25-4454-a0b1-79f7aeefaeba" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_2cd4024c-e57f-4a9d-861b-7d573a4ebff0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseAbstract_9b0103a0-5076-4bda-95ec-916f30a198af" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_2cd4024c-e57f-4a9d-861b-7d573a4ebff0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_c69740f9-9979-4ca7-843e-611659e79a0d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseAbstract_9b0103a0-5076-4bda-95ec-916f30a198af" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_c69740f9-9979-4ca7-843e-611659e79a0d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_c1c89a98-9a83-42ae-be78-f39b66b058b8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseAbstract_9b0103a0-5076-4bda-95ec-916f30a198af" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_c1c89a98-9a83-42ae-be78-f39b66b058b8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_f11ac5ef-4821-4b2f-9f61-35a8ffb014dd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_09b127da-706e-468d-b60f-0ff37a67baac" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SupplementalCashFlowInformationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eaf9753c-841a-44a8-a42b-9eeb3d4b6df4" xlink:to="loc_us-gaap_SupplementalCashFlowInformationAbstract_09b127da-706e-468d-b60f-0ff37a67baac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPaidNet_3594ca75-affe-48a6-83c9-c3db36b24191" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_09b127da-706e-468d-b60f-0ff37a67baac" xlink:to="loc_us-gaap_InterestPaidNet_3594ca75-affe-48a6-83c9-c3db36b24191" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_24bd9777-74f9-4520-912e-19af5531b87a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxesPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_09b127da-706e-468d-b60f-0ff37a67baac" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_24bd9777-74f9-4520-912e-19af5531b87a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DistributionsFromEquityInvestmentsReceived_52bf61ee-15af-4d5d-841f-80b7a301131a" xlink:href="aqunf-20210630.xsd#aqunf_DistributionsFromEquityInvestmentsReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_09b127da-706e-468d-b60f-0ff37a67baac" xlink:to="loc_aqunf_DistributionsFromEquityInvestmentsReceived_52bf61ee-15af-4d5d-841f-80b7a301131a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_1e7e13d2-bde4-4bdf-bbbd-572f1b1e4f04" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_eaf9753c-841a-44a8-a42b-9eeb3d4b6df4" xlink:to="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_1e7e13d2-bde4-4bdf-bbbd-572f1b1e4f04" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1_468fb92d-262a-4e0d-bdb2-dcce0e89ad66" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_1e7e13d2-bde4-4bdf-bbbd-572f1b1e4f04" xlink:to="loc_us-gaap_NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1_468fb92d-262a-4e0d-bdb2-dcce0e89ad66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStockDividendReinvestmentPlan_63e67802-ec17-487a-a624-c07b2e2ddde1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStockDividendReinvestmentPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_1e7e13d2-bde4-4bdf-bbbd-572f1b1e4f04" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStockDividendReinvestmentPlan_63e67802-ec17-487a-a624-c07b2e2ddde1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockAmountIssued1_f702d680-d6e4-4927-90f3-31cf0a128ec1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConversionOfStockAmountIssued1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_1e7e13d2-bde4-4bdf-bbbd-572f1b1e4f04" xlink:to="loc_us-gaap_ConversionOfStockAmountIssued1_f702d680-d6e4-4927-90f3-31cf0a128ec1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SaleOfPropertyPlantAndEquipmentIntangibleAssetsAndAccruedLiabilitiesInExchangeOfNoteReceivable_e4060a6b-63af-4b59-8a5d-cf9b966cc752" xlink:href="aqunf-20210630.xsd#aqunf_SaleOfPropertyPlantAndEquipmentIntangibleAssetsAndAccruedLiabilitiesInExchangeOfNoteReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_1e7e13d2-bde4-4bdf-bbbd-572f1b1e4f04" xlink:to="loc_aqunf_SaleOfPropertyPlantAndEquipmentIntangibleAssetsAndAccruedLiabilitiesInExchangeOfNoteReceivable_e4060a6b-63af-4b59-8a5d-cf9b966cc752" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_f8bf28ac-95f4-475a-aa45-d0a3f9e7db30" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_eaf9753c-841a-44a8-a42b-9eeb3d4b6df4" xlink:to="loc_us-gaap_StatementTable_f8bf28ac-95f4-475a-aa45-d0a3f9e7db30" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_9bc27456-32e5-474a-b5a0-e1439983c4c1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_f8bf28ac-95f4-475a-aa45-d0a3f9e7db30" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_9bc27456-32e5-474a-b5a0-e1439983c4c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_9bc27456-32e5-474a-b5a0-e1439983c4c1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_9bc27456-32e5-474a-b5a0-e1439983c4c1" xlink:to="loc_us-gaap_EquityComponentDomain_9bc27456-32e5-474a-b5a0-e1439983c4c1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_45c277e1-6ae7-43ab-af02-31cf20da70cc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_9bc27456-32e5-474a-b5a0-e1439983c4c1" xlink:to="loc_us-gaap_EquityComponentDomain_45c277e1-6ae7-43ab-af02-31cf20da70cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ConvertibleDebenturesMember_50e3079f-9642-43a7-84ea-8af47e1c9db8" xlink:href="aqunf-20210630.xsd#aqunf_ConvertibleDebenturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_45c277e1-6ae7-43ab-af02-31cf20da70cc" xlink:to="loc_aqunf_ConvertibleDebenturesMember_50e3079f-9642-43a7-84ea-8af47e1c9db8" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/BusinessandassetacquisitionsTables" xlink:type="simple" xlink:href="aqunf-20210630.xsd#BusinessandassetacquisitionsTables"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/BusinessandassetacquisitionsTables" xlink:type="extended" id="i37eb95cedf484bdc8a1bcda2e8a20720_BusinessandassetacquisitionsTables">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_7617f8e2-0bcf-4ff6-be6a-d69c526390f5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_17e7b91a-779d-461c-9dfd-8d26469c4398" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_7617f8e2-0bcf-4ff6-be6a-d69c526390f5" xlink:to="loc_us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_17e7b91a-779d-461c-9dfd-8d26469c4398" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_95ca59fc-9c6e-49fe-ba8f-ffe185eee85a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_7617f8e2-0bcf-4ff6-be6a-d69c526390f5" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_95ca59fc-9c6e-49fe-ba8f-ffe185eee85a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_a52a6534-f30a-4c16-a2a1-6b4e1e4110dc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_95ca59fc-9c6e-49fe-ba8f-ffe185eee85a" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_a52a6534-f30a-4c16-a2a1-6b4e1e4110dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a52a6534-f30a-4c16-a2a1-6b4e1e4110dc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_a52a6534-f30a-4c16-a2a1-6b4e1e4110dc" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a52a6534-f30a-4c16-a2a1-6b4e1e4110dc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1407f6b5-621e-4d99-a4ed-3e99ed1fa4bb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_a52a6534-f30a-4c16-a2a1-6b4e1e4110dc" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1407f6b5-621e-4d99-a4ed-3e99ed1fa4bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_MidWestWindDevelopmentProjectMember_2d4143ba-a6bb-40af-bfa4-bb6d3d046021" xlink:href="aqunf-20210630.xsd#aqunf_MidWestWindDevelopmentProjectMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1407f6b5-621e-4d99-a4ed-3e99ed1fa4bb" xlink:to="loc_aqunf_MidWestWindDevelopmentProjectMember_2d4143ba-a6bb-40af-bfa4-bb6d3d046021" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AltavistaSolarFacilityMember_c5e39dd6-db11-4c0d-94e5-cc2db74cb5cb" xlink:href="aqunf-20210630.xsd#aqunf_AltavistaSolarFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1407f6b5-621e-4d99-a4ed-3e99ed1fa4bb" xlink:to="loc_aqunf_AltavistaSolarFacilityMember_c5e39dd6-db11-4c0d-94e5-cc2db74cb5cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_MaverickCreekAndSugarCreekWindFacilitiesMember_c023b5d6-ac02-430b-be19-2d2877c4fe84" xlink:href="aqunf-20210630.xsd#aqunf_MaverickCreekAndSugarCreekWindFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_1407f6b5-621e-4d99-a4ed-3e99ed1fa4bb" xlink:to="loc_aqunf_MaverickCreekAndSugarCreekWindFacilitiesMember_c023b5d6-ac02-430b-be19-2d2877c4fe84" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/BusinessandassetacquisitionsDetails" xlink:type="simple" xlink:href="aqunf-20210630.xsd#BusinessandassetacquisitionsDetails"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/BusinessandassetacquisitionsDetails" xlink:type="extended" id="ibef2bd6aa6774f1086a566d3e0736215_BusinessandassetacquisitionsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NumberOfWindFarms_d2c3bc0b-baf1-4055-8925-469f102b00e7" xlink:href="aqunf-20210630.xsd#aqunf_NumberOfWindFarms"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_aqunf_NumberOfWindFarms_d2c3bc0b-baf1-4055-8925-469f102b00e7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_WindPowerCapacity_910fcd8a-151c-4888-b940-514b1685d666" xlink:href="aqunf-20210630.xsd#aqunf_WindPowerCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_aqunf_WindPowerCapacity_910fcd8a-151c-4888-b940-514b1685d666" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_BusinessCombinationTaxEquityFunding_442b660d-e641-4b83-9ccf-ff802721734d" xlink:href="aqunf-20210630.xsd#aqunf_BusinessCombinationTaxEquityFunding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_aqunf_BusinessCombinationTaxEquityFunding_442b660d-e641-4b83-9ccf-ff802721734d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_439d926e-16f9-4aaf-9221-d67ae14380b7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_439d926e-16f9-4aaf-9221-d67ae14380b7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredOther1_be8da0d8-9644-4a07-b03d-612d06a7c081" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredOther1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredOther1_be8da0d8-9644-4a07-b03d-612d06a7c081" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_87015798-3116-49c3-ae73-62493e4fb079" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_87015798-3116-49c3-ae73-62493e4fb079" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsWorkingCapital_ffe7e2a9-3186-4640-9637-bfc1fba76a24" xlink:href="aqunf-20210630.xsd#aqunf_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsWorkingCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_87015798-3116-49c3-ae73-62493e4fb079" xlink:to="loc_aqunf_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsWorkingCapital_ffe7e2a9-3186-4640-9637-bfc1fba76a24" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_1b453cd6-3b22-423d-9aba-dbe14d8d0a77" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_87015798-3116-49c3-ae73-62493e4fb079" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_1b453cd6-3b22-423d-9aba-dbe14d8d0a77" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_6088bc98-2ffb-4085-8f4f-4846bf1b2d80" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_87015798-3116-49c3-ae73-62493e4fb079" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_6088bc98-2ffb-4085-8f4f-4846bf1b2d80" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAssetRetirementObligation_e29a8db6-f30f-4ab8-b473-74d8e082436b" xlink:href="aqunf-20210630.xsd#aqunf_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAssetRetirementObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_87015798-3116-49c3-ae73-62493e4fb079" xlink:to="loc_aqunf_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesAssetRetirementObligation_e29a8db6-f30f-4ab8-b473-74d8e082436b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_211f5aec-16f4-46dc-b40d-9941007b3a92" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_87015798-3116-49c3-ae73-62493e4fb079" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_211f5aec-16f4-46dc-b40d-9941007b3a92" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_5622a5cc-71cb-459c-a3dd-d79522e4968f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_87015798-3116-49c3-ae73-62493e4fb079" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_5622a5cc-71cb-459c-a3dd-d79522e4968f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNoncontrollingInterest_9135d3f9-8eba-4116-a795-111bca68adf9" xlink:href="aqunf-20210630.xsd#aqunf_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_87015798-3116-49c3-ae73-62493e4fb079" xlink:to="loc_aqunf_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNoncontrollingInterest_9135d3f9-8eba-4116-a795-111bca68adf9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedDerivativeAssets_582423be-0a30-4b57-88ea-458c085d7fae" xlink:href="aqunf-20210630.xsd#aqunf_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedDerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_87015798-3116-49c3-ae73-62493e4fb079" xlink:to="loc_aqunf_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedDerivativeAssets_582423be-0a30-4b57-88ea-458c085d7fae" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_8b2dab47-ab7c-4636-9a30-2ce659d8240e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_87015798-3116-49c3-ae73-62493e4fb079" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_8b2dab47-ab7c-4636-9a30-2ce659d8240e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_b5dee46c-32b0-44db-bc05-7647f952966a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_87015798-3116-49c3-ae73-62493e4fb079" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_b5dee46c-32b0-44db-bc05-7647f952966a" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetOfCashAndCashEquivalents_ef0c9b89-8919-43a5-bc40-5a9cc015e498" xlink:href="aqunf-20210630.xsd#aqunf_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetOfCashAndCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_87015798-3116-49c3-ae73-62493e4fb079" xlink:to="loc_aqunf_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetOfCashAndCashEquivalents_ef0c9b89-8919-43a5-bc40-5a9cc015e498" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_0d12791c-171a-4086-bfc1-5a95b7cc87c0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_0d12791c-171a-4086-bfc1-5a95b7cc87c0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SolarPowerCapacity_9926fcaa-e872-4894-960d-3713061c4850" xlink:href="aqunf-20210630.xsd#aqunf_SolarPowerCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_aqunf_SolarPowerCapacity_9926fcaa-e872-4894-960d-3713061c4850" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_feb5e6f4-0cb9-4bad-af1e-fcd884304207" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_feb5e6f4-0cb9-4bad-af1e-fcd884304207" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_27973cb7-cbe8-4678-88ed-aef0a96defc0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_27973cb7-cbe8-4678-88ed-aef0a96defc0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AccrualsAndLongTermDebtPurchaseAccountingAdjustments_0f133702-0c7b-4ccd-98f7-6db899ff9ece" xlink:href="aqunf-20210630.xsd#aqunf_AccrualsAndLongTermDebtPurchaseAccountingAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_aqunf_AccrualsAndLongTermDebtPurchaseAccountingAdjustments_0f133702-0c7b-4ccd-98f7-6db899ff9ece" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillPurchaseAccountingAdjustments_5afb92cf-ac80-49c9-ab71-6d6788d98257" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GoodwillPurchaseAccountingAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_us-gaap_GoodwillPurchaseAccountingAdjustments_5afb92cf-ac80-49c9-ab71-6d6788d98257" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DisposalOfPartialInterestInConsolidatedEntityOwnershipInterestDisposed_4f3b3877-f4ff-4392-a576-0cc23e2e1156" xlink:href="aqunf-20210630.xsd#aqunf_DisposalOfPartialInterestInConsolidatedEntityOwnershipInterestDisposed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_aqunf_DisposalOfPartialInterestInConsolidatedEntityOwnershipInterestDisposed_4f3b3877-f4ff-4392-a576-0cc23e2e1156" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NoncontrollingInterestDisposedAmount_517ed317-03c1-4b47-b83a-8dc1126fcba1" xlink:href="aqunf-20210630.xsd#aqunf_NoncontrollingInterestDisposedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_aqunf_NoncontrollingInterestDisposedAmount_517ed317-03c1-4b47-b83a-8dc1126fcba1" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_f027f836-6ced-449f-a614-fa0f1045a1e6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_f027f836-6ced-449f-a614-fa0f1045a1e6" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare_c394a388-1b8d-48f5-aca5-9cbd0e64d85f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare_c394a388-1b8d-48f5-aca5-9cbd0e64d85f" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8d24f742-6a9f-453c-be2d-0f9a9c6deb72" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e557736-d9f2-4455-ac94-29468d759445" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8d24f742-6a9f-453c-be2d-0f9a9c6deb72" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_f26254d6-82bc-4910-a9c0-d8cac3048a55" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8d24f742-6a9f-453c-be2d-0f9a9c6deb72" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_f26254d6-82bc-4910-a9c0-d8cac3048a55" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f26254d6-82bc-4910-a9c0-d8cac3048a55_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_f26254d6-82bc-4910-a9c0-d8cac3048a55" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f26254d6-82bc-4910-a9c0-d8cac3048a55_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8cc472a5-1b4c-47fd-b4c3-79e1cf0a3a2f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_f26254d6-82bc-4910-a9c0-d8cac3048a55" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8cc472a5-1b4c-47fd-b4c3-79e1cf0a3a2f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_MidWestWindDevelopmentProjectMember_dd4fe59b-c754-460f-97d6-d7bf62f8d225" xlink:href="aqunf-20210630.xsd#aqunf_MidWestWindDevelopmentProjectMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8cc472a5-1b4c-47fd-b4c3-79e1cf0a3a2f" xlink:to="loc_aqunf_MidWestWindDevelopmentProjectMember_dd4fe59b-c754-460f-97d6-d7bf62f8d225" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SouthwesternMissouriWindProjectsMember_bef6bf00-d288-408d-a982-df49f6f93c79" xlink:href="aqunf-20210630.xsd#aqunf_SouthwesternMissouriWindProjectsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8cc472a5-1b4c-47fd-b4c3-79e1cf0a3a2f" xlink:to="loc_aqunf_SouthwesternMissouriWindProjectsMember_bef6bf00-d288-408d-a982-df49f6f93c79" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NorthForkRidgeWindProjectMember_23cfaab7-624e-4972-9c52-5b7f78ce9f39" xlink:href="aqunf-20210630.xsd#aqunf_NorthForkRidgeWindProjectMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8cc472a5-1b4c-47fd-b4c3-79e1cf0a3a2f" xlink:to="loc_aqunf_NorthForkRidgeWindProjectMember_23cfaab7-624e-4972-9c52-5b7f78ce9f39" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AltavistaSolarFacilityMember_bd617306-e741-44e9-9f69-615e08b84f23" xlink:href="aqunf-20210630.xsd#aqunf_AltavistaSolarFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8cc472a5-1b4c-47fd-b4c3-79e1cf0a3a2f" xlink:to="loc_aqunf_AltavistaSolarFacilityMember_bd617306-e741-44e9-9f69-615e08b84f23" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_MaverickCreekAndSugarCreekWindFacilitiesMember_5c6109af-aab0-4ce5-87fa-8d52da75552a" xlink:href="aqunf-20210630.xsd#aqunf_MaverickCreekAndSugarCreekWindFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8cc472a5-1b4c-47fd-b4c3-79e1cf0a3a2f" xlink:to="loc_aqunf_MaverickCreekAndSugarCreekWindFacilitiesMember_5c6109af-aab0-4ce5-87fa-8d52da75552a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_MaverickCreekWindFacilityMember_fd753987-94a3-4085-8b59-e9842257849d" xlink:href="aqunf-20210630.xsd#aqunf_MaverickCreekWindFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_MaverickCreekAndSugarCreekWindFacilitiesMember_5c6109af-aab0-4ce5-87fa-8d52da75552a" xlink:to="loc_aqunf_MaverickCreekWindFacilityMember_fd753987-94a3-4085-8b59-e9842257849d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SugarCreekWindFacilityMember_17578528-3656-4ab3-81be-f9c58705a7ec" xlink:href="aqunf-20210630.xsd#aqunf_SugarCreekWindFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_MaverickCreekAndSugarCreekWindFacilitiesMember_5c6109af-aab0-4ce5-87fa-8d52da75552a" xlink:to="loc_aqunf_SugarCreekWindFacilityMember_17578528-3656-4ab3-81be-f9c58705a7ec" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ESSALMember_3fa2f1b2-4e55-4d68-80fc-73e380987a50" xlink:href="aqunf-20210630.xsd#aqunf_ESSALMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8cc472a5-1b4c-47fd-b4c3-79e1cf0a3a2f" xlink:to="loc_aqunf_ESSALMember_3fa2f1b2-4e55-4d68-80fc-73e380987a50" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_b514dfd4-64da-4077-98ec-f993b0168c9b" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8d24f742-6a9f-453c-be2d-0f9a9c6deb72" xlink:to="loc_srt_OwnershipAxis_b514dfd4-64da-4077-98ec-f993b0168c9b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_b514dfd4-64da-4077-98ec-f993b0168c9b_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_b514dfd4-64da-4077-98ec-f993b0168c9b" xlink:to="loc_srt_OwnershipDomain_b514dfd4-64da-4077-98ec-f993b0168c9b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_1452ab13-d9f8-433e-8c73-5714236f97f9" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_b514dfd4-64da-4077-98ec-f993b0168c9b" xlink:to="loc_srt_OwnershipDomain_1452ab13-d9f8-433e-8c73-5714236f97f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ThirdPartyMember_31e4a20a-6060-4f92-9e23-75e10259d72a" xlink:href="aqunf-20210630.xsd#aqunf_ThirdPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_1452ab13-d9f8-433e-8c73-5714236f97f9" xlink:to="loc_aqunf_ThirdPartyMember_31e4a20a-6060-4f92-9e23-75e10259d72a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ESSALMember_0c41bb1f-1a70-4fc9-b081-8086f16fc5dc" xlink:href="aqunf-20210630.xsd#aqunf_ESSALMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_1452ab13-d9f8-433e-8c73-5714236f97f9" xlink:to="loc_aqunf_ESSALMember_0c41bb1f-1a70-4fc9-b081-8086f16fc5dc" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/AccountsreceivableAdditionalInformationDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#AccountsreceivableAdditionalInformationDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/AccountsreceivableAdditionalInformationDetail" xlink:type="extended" id="i195a862976c44db5ab9e42f48a12f58d_AccountsreceivableAdditionalInformationDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_e36b13e1-551f-4ffa-a340-fc216ea16708" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsNotesAndLoansReceivableLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNet_aaf4fb26-4395-4900-af21-73bfcf610c1a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsReceivableNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_e36b13e1-551f-4ffa-a340-fc216ea16708" xlink:to="loc_us-gaap_AccountsReceivableNet_aaf4fb26-4395-4900-af21-73bfcf610c1a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_d3fe55d7-efc6-4da2-b305-80aa68cb1589" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_e36b13e1-551f-4ffa-a340-fc216ea16708" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_d3fe55d7-efc6-4da2-b305-80aa68cb1589" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_05bb8cee-ed1c-4634-bab6-cdee5587e143" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccountsNotesAndLoansReceivableLineItems_e36b13e1-551f-4ffa-a340-fc216ea16708" xlink:to="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_05bb8cee-ed1c-4634-bab6-cdee5587e143" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivablesByBillingStatusTypeAxis_2667e3e9-b9f6-447e-878e-6a25ab0137dd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivablesByBillingStatusTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAccountsNotesLoansAndFinancingReceivableTable_05bb8cee-ed1c-4634-bab6-cdee5587e143" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivablesByBillingStatusTypeAxis_2667e3e9-b9f6-447e-878e-6a25ab0137dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesBillingStatusDomain_2667e3e9-b9f6-447e-878e-6a25ab0137dd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReceivablesBillingStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivablesByBillingStatusTypeAxis_2667e3e9-b9f6-447e-878e-6a25ab0137dd" xlink:to="loc_us-gaap_ReceivablesBillingStatusDomain_2667e3e9-b9f6-447e-878e-6a25ab0137dd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivablesBillingStatusDomain_7a1a02d6-7763-467f-acd3-62d9d3d75e95" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReceivablesBillingStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivablesByBillingStatusTypeAxis_2667e3e9-b9f6-447e-878e-6a25ab0137dd" xlink:to="loc_us-gaap_ReceivablesBillingStatusDomain_7a1a02d6-7763-467f-acd3-62d9d3d75e95" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnbilledRevenuesMember_68feef40-3975-4bf2-996b-022c475fd44a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnbilledRevenuesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivablesBillingStatusDomain_7a1a02d6-7763-467f-acd3-62d9d3d75e95" xlink:to="loc_us-gaap_UnbilledRevenuesMember_68feef40-3975-4bf2-996b-022c475fd44a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/RegulatorymattersApprovedAnnualRevenueIncreasesDetails" xlink:type="simple" xlink:href="aqunf-20210630.xsd#RegulatorymattersApprovedAnnualRevenueIncreasesDetails"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/RegulatorymattersApprovedAnnualRevenueIncreasesDetails" xlink:type="extended" id="i1882d1505ba640818c02fadcd56edff6_RegulatorymattersApprovedAnnualRevenueIncreasesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilitiesLineItems_c84bd082-15d5-486a-b467-f7c6d744cde6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryLiabilitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_PublicUtilitiesWeightedAverageCostOfCapital_3a924b77-c425-4f41-9cd3-0b601fb4f0c7" xlink:href="aqunf-20210630.xsd#aqunf_PublicUtilitiesWeightedAverageCostOfCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_c84bd082-15d5-486a-b467-f7c6d744cde6" xlink:to="loc_aqunf_PublicUtilitiesWeightedAverageCostOfCapital_3a924b77-c425-4f41-9cd3-0b601fb4f0c7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_PublicUtilitiesApprovedRevenue_0c7763f5-e12b-4ff5-9fd9-c704b0165ceb" xlink:href="aqunf-20210630.xsd#aqunf_PublicUtilitiesApprovedRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_c84bd082-15d5-486a-b467-f7c6d744cde6" xlink:to="loc_aqunf_PublicUtilitiesApprovedRevenue_0c7763f5-e12b-4ff5-9fd9-c704b0165ceb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_PublicUtilitiesDeferredRevenue_4241b02c-290c-4c7a-a000-10730e65f099" xlink:href="aqunf-20210630.xsd#aqunf_PublicUtilitiesDeferredRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_c84bd082-15d5-486a-b467-f7c6d744cde6" xlink:to="loc_aqunf_PublicUtilitiesDeferredRevenue_4241b02c-290c-4c7a-a000-10730e65f099" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityAmortizationPeriod_de1e70ff-6f5b-4c90-803f-e54e090b7d07" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryLiabilityAmortizationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_c84bd082-15d5-486a-b467-f7c6d744cde6" xlink:to="loc_us-gaap_RegulatoryLiabilityAmortizationPeriod_de1e70ff-6f5b-4c90-803f-e54e090b7d07" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_PublicUtilitiesApprovedDistributionRevenueIncreaseDecreaseAmount_afdbc5ff-edf1-49c3-b0db-e7f74e64e90f" xlink:href="aqunf-20210630.xsd#aqunf_PublicUtilitiesApprovedDistributionRevenueIncreaseDecreaseAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_c84bd082-15d5-486a-b467-f7c6d744cde6" xlink:to="loc_aqunf_PublicUtilitiesApprovedDistributionRevenueIncreaseDecreaseAmount_afdbc5ff-edf1-49c3-b0db-e7f74e64e90f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount_f1d9a224-1336-440c-b16e-368e5a12e57d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_c84bd082-15d5-486a-b467-f7c6d744cde6" xlink:to="loc_us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount_f1d9a224-1336-440c-b16e-368e5a12e57d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_PublicUtilitiesApprovedStepIncreaseDecreaseAmount_0d6d49c0-f7bd-4736-b797-97d4f2fb044f" xlink:href="aqunf-20210630.xsd#aqunf_PublicUtilitiesApprovedStepIncreaseDecreaseAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_c84bd082-15d5-486a-b467-f7c6d744cde6" xlink:to="loc_aqunf_PublicUtilitiesApprovedStepIncreaseDecreaseAmount_0d6d49c0-f7bd-4736-b797-97d4f2fb044f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_PublicUtilitiesAdditionalApprovedStepIncreaseDecreaseAmount_cf800d8d-7aa5-472d-8bfc-bde8ad3f3fb9" xlink:href="aqunf-20210630.xsd#aqunf_PublicUtilitiesAdditionalApprovedStepIncreaseDecreaseAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_c84bd082-15d5-486a-b467-f7c6d744cde6" xlink:to="loc_aqunf_PublicUtilitiesAdditionalApprovedStepIncreaseDecreaseAmount_cf800d8d-7aa5-472d-8bfc-bde8ad3f3fb9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRegulatoryLiabilitiesTable_72a3153e-ff0e-444c-87eb-3372c53a0e13" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfRegulatoryLiabilitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_c84bd082-15d5-486a-b467-f7c6d744cde6" xlink:to="loc_us-gaap_ScheduleOfRegulatoryLiabilitiesTable_72a3153e-ff0e-444c-87eb-3372c53a0e13" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyAxis_4421a987-6b48-4c55-bd34-87d11fefe3ba" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryAgencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryLiabilitiesTable_72a3153e-ff0e-444c-87eb-3372c53a0e13" xlink:to="loc_us-gaap_RegulatoryAgencyAxis_4421a987-6b48-4c55-bd34-87d11fefe3ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_4421a987-6b48-4c55-bd34-87d11fefe3ba_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_4421a987-6b48-4c55-bd34-87d11fefe3ba" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_4421a987-6b48-4c55-bd34-87d11fefe3ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAgencyDomain_b5d94b7d-dccd-48c8-b4d7-5f5d0d4ba862" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryAgencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RegulatoryAgencyAxis_4421a987-6b48-4c55-bd34-87d11fefe3ba" xlink:to="loc_us-gaap_RegulatoryAgencyDomain_b5d94b7d-dccd-48c8-b4d7-5f5d0d4ba862" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_BELCOBermudaMember_f7ed318c-5e87-4f27-9a2e-0c2140e67eef" xlink:href="aqunf-20210630.xsd#aqunf_BELCOBermudaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_b5d94b7d-dccd-48c8-b4d7-5f5d0d4ba862" xlink:to="loc_aqunf_BELCOBermudaMember_f7ed318c-5e87-4f27-9a2e-0c2140e67eef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_EnergyNorthGasSystemMember_20921585-414c-4747-ba07-4254a408407b" xlink:href="aqunf-20210630.xsd#aqunf_EnergyNorthGasSystemMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_b5d94b7d-dccd-48c8-b4d7-5f5d0d4ba862" xlink:to="loc_aqunf_EnergyNorthGasSystemMember_20921585-414c-4747-ba07-4254a408407b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_VariousMember_f411ce4c-483d-45e9-95ae-504efdec1444" xlink:href="aqunf-20210630.xsd#aqunf_VariousMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAgencyDomain_b5d94b7d-dccd-48c8-b4d7-5f5d0d4ba862" xlink:to="loc_aqunf_VariousMember_f411ce4c-483d-45e9-95ae-504efdec1444" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_e3bb4b35-90c6-4c2b-bdaa-9141ecf997fc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryLiabilitiesTable_72a3153e-ff0e-444c-87eb-3372c53a0e13" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_e3bb4b35-90c6-4c2b-bdaa-9141ecf997fc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_e3bb4b35-90c6-4c2b-bdaa-9141ecf997fc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_e3bb4b35-90c6-4c2b-bdaa-9141ecf997fc" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_e3bb4b35-90c6-4c2b-bdaa-9141ecf997fc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_5659d413-9248-440b-8325-ccc995b2052b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_e3bb4b35-90c6-4c2b-bdaa-9141ecf997fc" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_5659d413-9248-440b-8325-ccc995b2052b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_c9e5f39f-1134-48c3-9eae-7b139122d3ad" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_5659d413-9248-440b-8325-ccc995b2052b" xlink:to="loc_us-gaap_SubsequentEventMember_c9e5f39f-1134-48c3-9eae-7b139122d3ad" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/RegulatorymattersRegulatoryAssetsandLiabilitiesDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#RegulatorymattersRegulatoryAssetsandLiabilitiesDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/RegulatorymattersRegulatoryAssetsandLiabilitiesDetail" xlink:type="extended" id="idd3f37f0c5f44297af1612ae3fd7d4bb_RegulatorymattersRegulatoryAssetsandLiabilitiesDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilitiesLineItems_62ed5c70-3390-4d0f-811b-6c258c6bf5e7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryLiabilitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssets_ca37bc8b-7acc-4620-abc3-7b4f6ba729b3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_62ed5c70-3390-4d0f-811b-6c258c6bf5e7" xlink:to="loc_us-gaap_RegulatoryAssets_ca37bc8b-7acc-4620-abc3-7b4f6ba729b3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetsCurrent_363651d4-982c-467c-9bc7-1de87ea3a206" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_62ed5c70-3390-4d0f-811b-6c258c6bf5e7" xlink:to="loc_us-gaap_RegulatoryAssetsCurrent_363651d4-982c-467c-9bc7-1de87ea3a206" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetsNoncurrent_c4b91b93-13dd-45f8-8d03-11af958f08cf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_62ed5c70-3390-4d0f-811b-6c258c6bf5e7" xlink:to="loc_us-gaap_RegulatoryAssetsNoncurrent_c4b91b93-13dd-45f8-8d03-11af958f08cf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilities_0384e255-8fc6-46f5-9554-6db4d06d6609" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_62ed5c70-3390-4d0f-811b-6c258c6bf5e7" xlink:to="loc_us-gaap_RegulatoryLiabilities_0384e255-8fc6-46f5-9554-6db4d06d6609" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityCurrent_2f3e6e42-d98a-455b-97bd-03e5f7797172" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_62ed5c70-3390-4d0f-811b-6c258c6bf5e7" xlink:to="loc_us-gaap_RegulatoryLiabilityCurrent_2f3e6e42-d98a-455b-97bd-03e5f7797172" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityNoncurrent_a84e2014-f2e6-46d2-bdec-7c82f74877da" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_62ed5c70-3390-4d0f-811b-6c258c6bf5e7" xlink:to="loc_us-gaap_RegulatoryLiabilityNoncurrent_a84e2014-f2e6-46d2-bdec-7c82f74877da" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRegulatoryLiabilitiesTable_764b88f4-d77c-45df-b753-65d28f5aed72" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfRegulatoryLiabilitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RegulatoryLiabilitiesLineItems_62ed5c70-3390-4d0f-811b-6c258c6bf5e7" xlink:to="loc_us-gaap_ScheduleOfRegulatoryLiabilitiesTable_764b88f4-d77c-45df-b753-65d28f5aed72" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetAxis_ba9de4a7-0524-4fdf-bb89-7447dd593401" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryAssetAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryLiabilitiesTable_764b88f4-d77c-45df-b753-65d28f5aed72" xlink:to="loc_us-gaap_RegulatoryAssetAxis_ba9de4a7-0524-4fdf-bb89-7447dd593401" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetDomain_ba9de4a7-0524-4fdf-bb89-7447dd593401_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryAssetDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RegulatoryAssetAxis_ba9de4a7-0524-4fdf-bb89-7447dd593401" xlink:to="loc_us-gaap_RegulatoryAssetDomain_ba9de4a7-0524-4fdf-bb89-7447dd593401_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssetDomain_e76efdf6-84cc-4b79-bd81-e58e8108194e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryAssetDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RegulatoryAssetAxis_ba9de4a7-0524-4fdf-bb89-7447dd593401" xlink:to="loc_us-gaap_RegulatoryAssetDomain_e76efdf6-84cc-4b79-bd81-e58e8108194e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_EnergyMember_bbbd3e6d-dced-47f7-905f-4c993859ce12" xlink:href="aqunf-20210630.xsd#aqunf_EnergyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_e76efdf6-84cc-4b79-bd81-e58e8108194e" xlink:to="loc_aqunf_EnergyMember_bbbd3e6d-dced-47f7-905f-4c993859ce12" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_RetiredGeneratingPlantMember_6b37e94f-e402-4a6d-924a-40f6e23e2675" xlink:href="aqunf-20210630.xsd#aqunf_RetiredGeneratingPlantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_e76efdf6-84cc-4b79-bd81-e58e8108194e" xlink:to="loc_aqunf_RetiredGeneratingPlantMember_6b37e94f-e402-4a6d-924a-40f6e23e2675" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementPlansCostsMember_d76c4021-a6c2-49ae-b128-2ec6bb53dd1c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PensionAndOtherPostretirementPlansCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_e76efdf6-84cc-4b79-bd81-e58e8108194e" xlink:to="loc_us-gaap_PensionAndOtherPostretirementPlansCostsMember_d76c4021-a6c2-49ae-b128-2ec6bb53dd1c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_RateAdjustmentMember_ba44a1f0-5917-421c-86d0-a1ec4556602b" xlink:href="aqunf-20210630.xsd#aqunf_RateAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_e76efdf6-84cc-4b79-bd81-e58e8108194e" xlink:to="loc_aqunf_RateAdjustmentMember_ba44a1f0-5917-421c-86d0-a1ec4556602b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalRestorationCostsMember_3783b4c8-5c60-4369-8e7d-42ca2ff6fe67" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EnvironmentalRestorationCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_e76efdf6-84cc-4b79-bd81-e58e8108194e" xlink:to="loc_us-gaap_EnvironmentalRestorationCostsMember_3783b4c8-5c60-4369-8e7d-42ca2ff6fe67" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_TaxesMember_a84a60ea-10c7-4ad9-aa1d-172d07f307a3" xlink:href="aqunf-20210630.xsd#aqunf_TaxesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_e76efdf6-84cc-4b79-bd81-e58e8108194e" xlink:to="loc_aqunf_TaxesMember_a84a60ea-10c7-4ad9-aa1d-172d07f307a3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DebtPremiumMember_538babff-96f5-4d33-b25b-b9fbcf090934" xlink:href="aqunf-20210630.xsd#aqunf_DebtPremiumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_e76efdf6-84cc-4b79-bd81-e58e8108194e" xlink:to="loc_aqunf_DebtPremiumMember_538babff-96f5-4d33-b25b-b9fbcf090934" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CustomerProgramsMember_d2a0c2fe-2880-42d8-b6a3-5c4dc43639f9" xlink:href="aqunf-20210630.xsd#aqunf_CustomerProgramsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_e76efdf6-84cc-4b79-bd81-e58e8108194e" xlink:to="loc_aqunf_CustomerProgramsMember_d2a0c2fe-2880-42d8-b6a3-5c4dc43639f9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DeferredCapitalizedCostsMember_e2a778d6-57ab-4e32-9995-bd46092b3448" xlink:href="aqunf-20210630.xsd#aqunf_DeferredCapitalizedCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_e76efdf6-84cc-4b79-bd81-e58e8108194e" xlink:to="loc_aqunf_DeferredCapitalizedCostsMember_e2a778d6-57ab-4e32-9995-bd46092b3448" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationCostsMember_136b615e-32ea-4c5d-b7b5-f4f1d0854878" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetRetirementObligationCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_e76efdf6-84cc-4b79-bd81-e58e8108194e" xlink:to="loc_us-gaap_AssetRetirementObligationCostsMember_136b615e-32ea-4c5d-b7b5-f4f1d0854878" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_WildfireMitigationAndVegetationManagementMember_bd523757-1c71-4fb1-b11a-c7200f52d7f4" xlink:href="aqunf-20210630.xsd#aqunf_WildfireMitigationAndVegetationManagementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_e76efdf6-84cc-4b79-bd81-e58e8108194e" xlink:to="loc_aqunf_WildfireMitigationAndVegetationManagementMember_bd523757-1c71-4fb1-b11a-c7200f52d7f4" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_LongtermMaintenanceContractMember_80e1e82e-acad-490e-8bad-f11ef19b77af" xlink:href="aqunf-20210630.xsd#aqunf_LongtermMaintenanceContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_e76efdf6-84cc-4b79-bd81-e58e8108194e" xlink:to="loc_aqunf_LongtermMaintenanceContractMember_80e1e82e-acad-490e-8bad-f11ef19b77af" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_RateCaseCostsMember_8b282233-6a2c-4d4b-8418-f5f13efe0fca" xlink:href="aqunf-20210630.xsd#aqunf_RateCaseCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_e76efdf6-84cc-4b79-bd81-e58e8108194e" xlink:to="loc_aqunf_RateCaseCostsMember_8b282233-6a2c-4d4b-8418-f5f13efe0fca" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherRegulatoryAssetsLiabilitiesMember_0fd90794-eff1-493c-9cf2-9da0ad3ac893" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherRegulatoryAssetsLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryAssetDomain_e76efdf6-84cc-4b79-bd81-e58e8108194e" xlink:to="loc_us-gaap_OtherRegulatoryAssetsLiabilitiesMember_0fd90794-eff1-493c-9cf2-9da0ad3ac893" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityAxis_f193a4b6-7c3f-4ad9-b3c5-8e96587f594c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryLiabilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRegulatoryLiabilitiesTable_764b88f4-d77c-45df-b753-65d28f5aed72" xlink:to="loc_us-gaap_RegulatoryLiabilityAxis_f193a4b6-7c3f-4ad9-b3c5-8e96587f594c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityDomain_f193a4b6-7c3f-4ad9-b3c5-8e96587f594c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryLiabilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RegulatoryLiabilityAxis_f193a4b6-7c3f-4ad9-b3c5-8e96587f594c" xlink:to="loc_us-gaap_RegulatoryLiabilityDomain_f193a4b6-7c3f-4ad9-b3c5-8e96587f594c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilityDomain_93fcdc1b-9a59-4576-8703-c0bed835a1e2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryLiabilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RegulatoryLiabilityAxis_f193a4b6-7c3f-4ad9-b3c5-8e96587f594c" xlink:to="loc_us-gaap_RegulatoryLiabilityDomain_93fcdc1b-9a59-4576-8703-c0bed835a1e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_TaxesMember_75a30e51-b8cb-44b6-b4d8-193f6f660d62" xlink:href="aqunf-20210630.xsd#aqunf_TaxesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_93fcdc1b-9a59-4576-8703-c0bed835a1e2" xlink:to="loc_aqunf_TaxesMember_75a30e51-b8cb-44b6-b4d8-193f6f660d62" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RemovalCostsMember_4c66b1e5-3838-4abd-b3f9-7e2fd5464ef3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RemovalCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_93fcdc1b-9a59-4576-8703-c0bed835a1e2" xlink:to="loc_us-gaap_RemovalCostsMember_4c66b1e5-3838-4abd-b3f9-7e2fd5464ef3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementPlansCostsMember_5d25aa69-a3a5-458a-8ba0-ff2f71025dc6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PensionAndOtherPostretirementPlansCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_93fcdc1b-9a59-4576-8703-c0bed835a1e2" xlink:to="loc_us-gaap_PensionAndOtherPostretirementPlansCostsMember_5d25aa69-a3a5-458a-8ba0-ff2f71025dc6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_EnergyMember_1bb08007-e4c2-4d3d-884b-0dcb3ea8ae52" xlink:href="aqunf-20210630.xsd#aqunf_EnergyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_93fcdc1b-9a59-4576-8703-c0bed835a1e2" xlink:to="loc_aqunf_EnergyMember_1bb08007-e4c2-4d3d-884b-0dcb3ea8ae52" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_RateAdjustmentMember_ac67a8d1-a1cf-469c-a46f-30f9da653a20" xlink:href="aqunf-20210630.xsd#aqunf_RateAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_93fcdc1b-9a59-4576-8703-c0bed835a1e2" xlink:to="loc_aqunf_RateAdjustmentMember_ac67a8d1-a1cf-469c-a46f-30f9da653a20" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CustomerProgramsMember_11fad2da-2039-49a9-8453-d41911dedb44" xlink:href="aqunf-20210630.xsd#aqunf_CustomerProgramsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_93fcdc1b-9a59-4576-8703-c0bed835a1e2" xlink:to="loc_aqunf_CustomerProgramsMember_11fad2da-2039-49a9-8453-d41911dedb44" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_6a11bb07-0537-4731-aa06-38284a5aa079" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_93fcdc1b-9a59-4576-8703-c0bed835a1e2" xlink:to="loc_us-gaap_BaseRateMember_6a11bb07-0537-4731-aa06-38284a5aa079" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherRegulatoryAssetsLiabilitiesMember_1e2c8478-d9e0-448d-98c1-1b14276ebd0b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherRegulatoryAssetsLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RegulatoryLiabilityDomain_93fcdc1b-9a59-4576-8703-c0bed835a1e2" xlink:to="loc_us-gaap_OtherRegulatoryAssetsLiabilitiesMember_1e2c8478-d9e0-448d-98c1-1b14276ebd0b" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/LongterminvestmentsScheduleofLongTermInvestmentsDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#LongterminvestmentsScheduleofLongTermInvestmentsDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/LongterminvestmentsScheduleofLongTermInvestmentsDetail" xlink:type="extended" id="i663f8846520b4825b00d6efa7c5ce857_LongterminvestmentsScheduleofLongTermInvestmentsDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_19e8013f-23a2-4275-87fd-545db83c3d99" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentsFairValueDisclosure_4ed6224c-e44e-4379-a914-a4f1d021a37f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityMethodInvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_19e8013f-23a2-4275-87fd-545db83c3d99" xlink:to="loc_us-gaap_EquityMethodInvestmentsFairValueDisclosure_4ed6224c-e44e-4379-a914-a4f1d021a37f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NoncontrollingInterestinPartnershipsandJointVentures_5192ab5b-e823-475d-9fdf-63d85a4f6830" xlink:href="aqunf-20210630.xsd#aqunf_NoncontrollingInterestinPartnershipsandJointVentures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_19e8013f-23a2-4275-87fd-545db83c3d99" xlink:to="loc_aqunf_NoncontrollingInterestinPartnershipsandJointVentures_5192ab5b-e823-475d-9fdf-63d85a4f6830" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesReceivableNet_a7838dbf-9902-4c51-ade0-047eeb8eb056" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NotesReceivableNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_19e8013f-23a2-4275-87fd-545db83c3d99" xlink:to="loc_us-gaap_NotesReceivableNet_a7838dbf-9902-4c51-ade0-047eeb8eb056" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherInvestments_4c071d36-f671-4731-8fca-43d262a7dd85" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_19e8013f-23a2-4275-87fd-545db83c3d99" xlink:to="loc_us-gaap_OtherInvestments_4c071d36-f671-4731-8fca-43d262a7dd85" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermInvestments_d52a89aa-fb16-4030-b08c-168980338bc4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_19e8013f-23a2-4275-87fd-545db83c3d99" xlink:to="loc_us-gaap_LongTermInvestments_d52a89aa-fb16-4030-b08c-168980338bc4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_ce502758-0939-40eb-b04f-7e4f2f4ad2ae" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_19e8013f-23a2-4275-87fd-545db83c3d99" xlink:to="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_ce502758-0939-40eb-b04f-7e4f2f4ad2ae" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_36360be7-21a3-42df-b19f-78c071ee52a6" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_ce502758-0939-40eb-b04f-7e4f2f4ad2ae" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_36360be7-21a3-42df-b19f-78c071ee52a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_36360be7-21a3-42df-b19f-78c071ee52a6_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_36360be7-21a3-42df-b19f-78c071ee52a6" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_36360be7-21a3-42df-b19f-78c071ee52a6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_4b02d72b-ed4b-4fea-b1de-2cbd645473cb" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_36360be7-21a3-42df-b19f-78c071ee52a6" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_4b02d72b-ed4b-4fea-b1de-2cbd645473cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AtlanticaYieldMember_25e9ab76-0804-42b8-8898-5770ec6413a1" xlink:href="aqunf-20210630.xsd#aqunf_AtlanticaYieldMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_4b02d72b-ed4b-4fea-b1de-2cbd645473cb" xlink:to="loc_aqunf_AtlanticaYieldMember_25e9ab76-0804-42b8-8898-5770ec6413a1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AtlanticaShareSubscriptionAgreementMember_d187a588-e3e0-48b8-899e-507db0e4fffd" xlink:href="aqunf-20210630.xsd#aqunf_AtlanticaShareSubscriptionAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_4b02d72b-ed4b-4fea-b1de-2cbd645473cb" xlink:to="loc_aqunf_AtlanticaShareSubscriptionAgreementMember_d187a588-e3e0-48b8-899e-507db0e4fffd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AYESCanadaMember_78060f2e-5f3a-49e1-83ba-3ae2779d2d08" xlink:href="aqunf-20210630.xsd#aqunf_AYESCanadaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_4b02d72b-ed4b-4fea-b1de-2cbd645473cb" xlink:to="loc_aqunf_AYESCanadaMember_78060f2e-5f3a-49e1-83ba-3ae2779d2d08" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_OtherLongTermInvestmentsAtFairValueMember_ef7f6b05-1f52-4581-9188-a18173dd34cd" xlink:href="aqunf-20210630.xsd#aqunf_OtherLongTermInvestmentsAtFairValueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_4b02d72b-ed4b-4fea-b1de-2cbd645473cb" xlink:to="loc_aqunf_OtherLongTermInvestmentsAtFairValueMember_ef7f6b05-1f52-4581-9188-a18173dd34cd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_1d113e55-5fae-4f5e-b213-9a5ec2c55515" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_ce502758-0939-40eb-b04f-7e4f2f4ad2ae" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_1d113e55-5fae-4f5e-b213-9a5ec2c55515" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_1d113e55-5fae-4f5e-b213-9a5ec2c55515_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_1d113e55-5fae-4f5e-b213-9a5ec2c55515" xlink:to="loc_us-gaap_ReceivableTypeDomain_1d113e55-5fae-4f5e-b213-9a5ec2c55515_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableTypeDomain_a0ce2b93-2dca-427f-a82a-64c730a5401d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReceivableTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis_1d113e55-5fae-4f5e-b213-9a5ec2c55515" xlink:to="loc_us-gaap_ReceivableTypeDomain_a0ce2b93-2dca-427f-a82a-64c730a5401d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesReceivableMember_da75bbf2-2a27-4d34-9ae6-188161a0ec06" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NotesReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivableTypeDomain_a0ce2b93-2dca-427f-a82a-64c730a5401d" xlink:to="loc_us-gaap_NotesReceivableMember_da75bbf2-2a27-4d34-9ae6-188161a0ec06" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NoteReceivableNameAxis_695b2e95-0089-4c5c-ae03-30602b76f1c2" xlink:href="aqunf-20210630.xsd#aqunf_NoteReceivableNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_ce502758-0939-40eb-b04f-7e4f2f4ad2ae" xlink:to="loc_aqunf_NoteReceivableNameAxis_695b2e95-0089-4c5c-ae03-30602b76f1c2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NoteReceivableNameDomain_695b2e95-0089-4c5c-ae03-30602b76f1c2_default" xlink:href="aqunf-20210630.xsd#aqunf_NoteReceivableNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_aqunf_NoteReceivableNameAxis_695b2e95-0089-4c5c-ae03-30602b76f1c2" xlink:to="loc_aqunf_NoteReceivableNameDomain_695b2e95-0089-4c5c-ae03-30602b76f1c2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NoteReceivableNameDomain_1fbf77fa-0399-4f72-80cc-56620e06501c" xlink:href="aqunf-20210630.xsd#aqunf_NoteReceivableNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_aqunf_NoteReceivableNameAxis_695b2e95-0089-4c5c-ae03-30602b76f1c2" xlink:to="loc_aqunf_NoteReceivableNameDomain_1fbf77fa-0399-4f72-80cc-56620e06501c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DevelopmentLoansMember_7b5ffb67-6931-4ba0-b9db-02bf84d39606" xlink:href="aqunf-20210630.xsd#aqunf_DevelopmentLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_NoteReceivableNameDomain_1fbf77fa-0399-4f72-80cc-56620e06501c" xlink:to="loc_aqunf_DevelopmentLoansMember_7b5ffb67-6931-4ba0-b9db-02bf84d39606" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/LongterminvestmentsIncomefromLongtermInvestmentsDetails" xlink:type="simple" xlink:href="aqunf-20210630.xsd#LongterminvestmentsIncomefromLongtermInvestmentsDetails"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/LongterminvestmentsIncomefromLongtermInvestmentsDetails" xlink:type="extended" id="ibfd049c31c914b6691700aa0444a4835_LongterminvestmentsIncomefromLongtermInvestmentsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_21278f52-aa86-4ba3-9354-a3a9841442ec" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_EquityMethodInvestmentFairValueGainLoss_5aa4e46f-b1d8-4fa2-9a7f-1b26c9468dd6" xlink:href="aqunf-20210630.xsd#aqunf_EquityMethodInvestmentFairValueGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_21278f52-aa86-4ba3-9354-a3a9841442ec" xlink:to="loc_aqunf_EquityMethodInvestmentFairValueGainLoss_5aa4e46f-b1d8-4fa2-9a7f-1b26c9468dd6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_EquityMethodInvestmentInterestIncome_28365284-9897-452a-9197-dd48880d8349" xlink:href="aqunf-20210630.xsd#aqunf_EquityMethodInvestmentInterestIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_21278f52-aa86-4ba3-9354-a3a9841442ec" xlink:to="loc_aqunf_EquityMethodInvestmentInterestIncome_28365284-9897-452a-9197-dd48880d8349" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestments_7c8d9294-6b57-43d7-aedc-19ebd9a8fb68" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_21278f52-aa86-4ba3-9354-a3a9841442ec" xlink:to="loc_us-gaap_IncomeLossFromEquityMethodInvestments_7c8d9294-6b57-43d7-aedc-19ebd9a8fb68" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_InterestandOtherIncomefromEquityMethodInvestments_5b790fa2-4dae-4002-a478-e3283cbfb41a" xlink:href="aqunf-20210630.xsd#aqunf_InterestandOtherIncomefromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_21278f52-aa86-4ba3-9354-a3a9841442ec" xlink:to="loc_aqunf_InterestandOtherIncomefromEquityMethodInvestments_5b790fa2-4dae-4002-a478-e3283cbfb41a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnInvestments_46a2a314-1f93-4923-a498-0090c45b8739" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainLossOnInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_21278f52-aa86-4ba3-9354-a3a9841442ec" xlink:to="loc_us-gaap_GainLossOnInvestments_46a2a314-1f93-4923-a498-0090c45b8739" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_80dcb46e-ebac-49d5-b497-b2339c437370" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_21278f52-aa86-4ba3-9354-a3a9841442ec" xlink:to="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_80dcb46e-ebac-49d5-b497-b2339c437370" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_448ab318-e4ad-4145-98d7-85feee93702b" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_80dcb46e-ebac-49d5-b497-b2339c437370" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_448ab318-e4ad-4145-98d7-85feee93702b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_448ab318-e4ad-4145-98d7-85feee93702b_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_448ab318-e4ad-4145-98d7-85feee93702b" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_448ab318-e4ad-4145-98d7-85feee93702b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_aed7e51a-a6c7-4f5e-bc48-cf904abbd105" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_448ab318-e4ad-4145-98d7-85feee93702b" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_aed7e51a-a6c7-4f5e-bc48-cf904abbd105" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AtlanticaYieldMember_a756911f-24d3-4a01-b3b5-157982734fb2" xlink:href="aqunf-20210630.xsd#aqunf_AtlanticaYieldMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_aed7e51a-a6c7-4f5e-bc48-cf904abbd105" xlink:to="loc_aqunf_AtlanticaYieldMember_a756911f-24d3-4a01-b3b5-157982734fb2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AYESCanadaMember_2663c748-84af-417a-9172-17c31a675d4c" xlink:href="aqunf-20210630.xsd#aqunf_AYESCanadaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_aed7e51a-a6c7-4f5e-bc48-cf904abbd105" xlink:to="loc_aqunf_AYESCanadaMember_2663c748-84af-417a-9172-17c31a675d4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_InvestmentsOtherMember_ace3671f-4a31-4c22-b5db-6f004e0cd3dd" xlink:href="aqunf-20210630.xsd#aqunf_InvestmentsOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_aed7e51a-a6c7-4f5e-bc48-cf904abbd105" xlink:to="loc_aqunf_InvestmentsOtherMember_ace3671f-4a31-4c22-b5db-6f004e0cd3dd" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/LongterminvestmentsAdditionalInformationDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#LongterminvestmentsAdditionalInformationDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/LongterminvestmentsAdditionalInformationDetail" xlink:type="extended" id="i83ba52da4c4d410580580d4b10f95a7e_LongterminvestmentsAdditionalInformationDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_ec45052d-14e7-43ab-bfd6-170099fb6239" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_99e0b616-306b-41f5-95c2-c2517bd046e7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_ec45052d-14e7-43ab-bfd6-170099fb6239" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_99e0b616-306b-41f5-95c2-c2517bd046e7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnderlyingDerivativeLiability_85869f37-6e4b-411d-8989-ea583980947c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnderlyingDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_ec45052d-14e7-43ab-bfd6-170099fb6239" xlink:to="loc_us-gaap_UnderlyingDerivativeLiability_85869f37-6e4b-411d-8989-ea583980947c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForDerivativeInstrumentInvestingActivities_3c43b48c-0b6a-4e40-b8f0-47a70fbd5ef1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsForDerivativeInstrumentInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_ec45052d-14e7-43ab-bfd6-170099fb6239" xlink:to="loc_us-gaap_PaymentsForDerivativeInstrumentInvestingActivities_3c43b48c-0b6a-4e40-b8f0-47a70fbd5ef1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentOwnedBalanceShares_02ae9540-bdf0-4212-8fc3-3f6a5ef51e48" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InvestmentOwnedBalanceShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_ec45052d-14e7-43ab-bfd6-170099fb6239" xlink:to="loc_us-gaap_InvestmentOwnedBalanceShares_02ae9540-bdf0-4212-8fc3-3f6a5ef51e48" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments_1016c9cd-4c61-4ccf-a0a7-b6faabe8231b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_ec45052d-14e7-43ab-bfd6-170099fb6239" xlink:to="loc_us-gaap_EquityMethodInvestments_1016c9cd-4c61-4ccf-a0a7-b6faabe8231b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NoncontrollingInterestinPartnershipsandJointVentures_ef93038c-7dcc-4969-bb68-ba7fff78b3cb" xlink:href="aqunf-20210630.xsd#aqunf_NoncontrollingInterestinPartnershipsandJointVentures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_ec45052d-14e7-43ab-bfd6-170099fb6239" xlink:to="loc_aqunf_NoncontrollingInterestinPartnershipsandJointVentures_ef93038c-7dcc-4969-bb68-ba7fff78b3cb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsNet_8d5e9a47-4c96-4340-adc9-3830cfa570b3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_ec45052d-14e7-43ab-bfd6-170099fb6239" xlink:to="loc_us-gaap_AssetsNet_8d5e9a47-4c96-4340-adc9-3830cfa570b3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NumberOfWindDevelopmentProjectsAcquired_6b426e37-32c8-4b9f-8d2c-a54460745ec1" xlink:href="aqunf-20210630.xsd#aqunf_NumberOfWindDevelopmentProjectsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_ec45052d-14e7-43ab-bfd6-170099fb6239" xlink:to="loc_aqunf_NumberOfWindDevelopmentProjectsAcquired_6b426e37-32c8-4b9f-8d2c-a54460745ec1" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NumberOfWindDevelopmentProjects_7a3376ce-96b1-46a6-b1cc-641066c81183" xlink:href="aqunf-20210630.xsd#aqunf_NumberOfWindDevelopmentProjects"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_ec45052d-14e7-43ab-bfd6-170099fb6239" xlink:to="loc_aqunf_NumberOfWindDevelopmentProjects_7a3376ce-96b1-46a6-b1cc-641066c81183" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_f3a5965f-5e47-4fae-b1d6-3bd33ec40b8b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_ec45052d-14e7-43ab-bfd6-170099fb6239" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_f3a5965f-5e47-4fae-b1d6-3bd33ec40b8b" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_5bc90d3c-7197-43a8-ae05-be3074cedfce" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_ec45052d-14e7-43ab-bfd6-170099fb6239" xlink:to="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_5bc90d3c-7197-43a8-ae05-be3074cedfce" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SolarPowerCapacity_51899810-5dc1-4fa3-9bb9-01b5c17bc045" xlink:href="aqunf-20210630.xsd#aqunf_SolarPowerCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_ec45052d-14e7-43ab-bfd6-170099fb6239" xlink:to="loc_aqunf_SolarPowerCapacity_51899810-5dc1-4fa3-9bb9-01b5c17bc045" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityFinancialOrOtherSupportAmount_410bb69d-e21a-4a14-8516-dcdeb36c10cb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableInterestEntityFinancialOrOtherSupportAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_ec45052d-14e7-43ab-bfd6-170099fb6239" xlink:to="loc_us-gaap_VariableInterestEntityFinancialOrOtherSupportAmount_410bb69d-e21a-4a14-8516-dcdeb36c10cb" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_71c9fee6-3b12-4846-ae64-f18931688d00" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_ec45052d-14e7-43ab-bfd6-170099fb6239" xlink:to="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_71c9fee6-3b12-4846-ae64-f18931688d00" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_62392334-010e-459c-b165-e38ed87c2438" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_71c9fee6-3b12-4846-ae64-f18931688d00" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_62392334-010e-459c-b165-e38ed87c2438" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_62392334-010e-459c-b165-e38ed87c2438_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_62392334-010e-459c-b165-e38ed87c2438" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_62392334-010e-459c-b165-e38ed87c2438_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_62c69acb-1dbb-41c0-a919-c5b986acc21a" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_62392334-010e-459c-b165-e38ed87c2438" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_62c69acb-1dbb-41c0-a919-c5b986acc21a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AtlanticaYieldMember_ba200d4e-51da-4816-9c6b-7499d29bf910" xlink:href="aqunf-20210630.xsd#aqunf_AtlanticaYieldMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_62c69acb-1dbb-41c0-a919-c5b986acc21a" xlink:to="loc_aqunf_AtlanticaYieldMember_ba200d4e-51da-4816-9c6b-7499d29bf910" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_TexasWindFarmsMember_01f12477-6429-4656-a885-a3ff1fe20734" xlink:href="aqunf-20210630.xsd#aqunf_TexasWindFarmsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_62c69acb-1dbb-41c0-a919-c5b986acc21a" xlink:to="loc_aqunf_TexasWindFarmsMember_01f12477-6429-4656-a885-a3ff1fe20734" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_FourthTexasWindFacilityMember_bd30e29b-f916-4a01-a559-271c9ad1e42e" xlink:href="aqunf-20210630.xsd#aqunf_FourthTexasWindFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_62c69acb-1dbb-41c0-a919-c5b986acc21a" xlink:to="loc_aqunf_FourthTexasWindFacilityMember_bd30e29b-f916-4a01-a559-271c9ad1e42e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SugarCreekMember_18aa0e4f-2619-4abf-9f0f-20ba42e4f885" xlink:href="aqunf-20210630.xsd#aqunf_SugarCreekMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_62c69acb-1dbb-41c0-a919-c5b986acc21a" xlink:to="loc_aqunf_SugarCreekMember_18aa0e4f-2619-4abf-9f0f-20ba42e4f885" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_MaverickMember_92923fbd-c160-41fd-8708-566a74f0cb92" xlink:href="aqunf-20210630.xsd#aqunf_MaverickMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_62c69acb-1dbb-41c0-a919-c5b986acc21a" xlink:to="loc_aqunf_MaverickMember_92923fbd-c160-41fd-8708-566a74f0cb92" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_MaverickCreekAndSugarCreekWindFacilitiesMember_57e733fa-769e-4547-82df-02010bd61f75" xlink:href="aqunf-20210630.xsd#aqunf_MaverickCreekAndSugarCreekWindFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_62c69acb-1dbb-41c0-a919-c5b986acc21a" xlink:to="loc_aqunf_MaverickCreekAndSugarCreekWindFacilitiesMember_57e733fa-769e-4547-82df-02010bd61f75" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NorthForkRidgeAndKingsPointFacilitiesMember_c1fae728-e7a2-40e8-8747-ec21c068d348" xlink:href="aqunf-20210630.xsd#aqunf_NorthForkRidgeAndKingsPointFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_62c69acb-1dbb-41c0-a919-c5b986acc21a" xlink:to="loc_aqunf_NorthForkRidgeAndKingsPointFacilitiesMember_c1fae728-e7a2-40e8-8747-ec21c068d348" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_64266be2-b35b-46fe-8ec8-fa5db3e3fe39" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_71c9fee6-3b12-4846-ae64-f18931688d00" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_64266be2-b35b-46fe-8ec8-fa5db3e3fe39" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_64266be2-b35b-46fe-8ec8-fa5db3e3fe39_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_64266be2-b35b-46fe-8ec8-fa5db3e3fe39" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_64266be2-b35b-46fe-8ec8-fa5db3e3fe39_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_965f8332-068a-4c84-87c0-869ce8f47817" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_64266be2-b35b-46fe-8ec8-fa5db3e3fe39" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_965f8332-068a-4c84-87c0-869ce8f47817" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityContractMember_5dc603af-0c51-4d4a-b510-eb601756287d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_965f8332-068a-4c84-87c0-869ce8f47817" xlink:to="loc_us-gaap_EquityContractMember_5dc603af-0c51-4d4a-b510-eb601756287d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_701788de-3ff6-4a89-b7dd-48a972172ba9" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_71c9fee6-3b12-4846-ae64-f18931688d00" xlink:to="loc_srt_RangeAxis_701788de-3ff6-4a89-b7dd-48a972172ba9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_701788de-3ff6-4a89-b7dd-48a972172ba9_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_701788de-3ff6-4a89-b7dd-48a972172ba9" xlink:to="loc_srt_RangeMember_701788de-3ff6-4a89-b7dd-48a972172ba9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_e32b58a2-be4b-47b2-8918-6daec32c9ab7" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_701788de-3ff6-4a89-b7dd-48a972172ba9" xlink:to="loc_srt_RangeMember_e32b58a2-be4b-47b2-8918-6daec32c9ab7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_4b61634a-a5e7-4591-b8f1-9cfb42dd9d6c" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_e32b58a2-be4b-47b2-8918-6daec32c9ab7" xlink:to="loc_srt_MaximumMember_4b61634a-a5e7-4591-b8f1-9cfb42dd9d6c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_e5b46858-f23c-42b7-b318-aa0bc33a244a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_71c9fee6-3b12-4846-ae64-f18931688d00" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_e5b46858-f23c-42b7-b318-aa0bc33a244a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e5b46858-f23c-42b7-b318-aa0bc33a244a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_e5b46858-f23c-42b7-b318-aa0bc33a244a" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e5b46858-f23c-42b7-b318-aa0bc33a244a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_34cfed32-6951-4e7a-b457-5b25c6526a35" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_e5b46858-f23c-42b7-b318-aa0bc33a244a" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_34cfed32-6951-4e7a-b457-5b25c6526a35" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_MaverickCreekAndSugarCreekWindFacilitiesMember_73342b51-4ff0-4918-a61c-8d53ea0206c6" xlink:href="aqunf-20210630.xsd#aqunf_MaverickCreekAndSugarCreekWindFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_34cfed32-6951-4e7a-b457-5b25c6526a35" xlink:to="loc_aqunf_MaverickCreekAndSugarCreekWindFacilitiesMember_73342b51-4ff0-4918-a61c-8d53ea0206c6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AltavistaMember_edebb574-5bf0-4a3d-b138-f5a292effcf5" xlink:href="aqunf-20210630.xsd#aqunf_AltavistaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_34cfed32-6951-4e7a-b457-5b25c6526a35" xlink:to="loc_aqunf_AltavistaMember_edebb574-5bf0-4a3d-b138-f5a292effcf5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_9f673099-ff2f-420e-88ef-d0c6ca4b1308" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_71c9fee6-3b12-4846-ae64-f18931688d00" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_9f673099-ff2f-420e-88ef-d0c6ca4b1308" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_9f673099-ff2f-420e-88ef-d0c6ca4b1308_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_9f673099-ff2f-420e-88ef-d0c6ca4b1308" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_9f673099-ff2f-420e-88ef-d0c6ca4b1308_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_8ca555b2-54fb-4c32-9c86-aaaba2965ada" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_9f673099-ff2f-420e-88ef-d0c6ca4b1308" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_8ca555b2-54fb-4c32-9c86-aaaba2965ada" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_dd78f797-47bf-4405-ba20-63bdd255097f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_8ca555b2-54fb-4c32-9c86-aaaba2965ada" xlink:to="loc_us-gaap_SubsequentEventMember_dd78f797-47bf-4405-ba20-63bdd255097f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/LongterminvestmentsInvestmentsinSignificantPartnershipsandJointVenturesDetails" xlink:type="simple" xlink:href="aqunf-20210630.xsd#LongterminvestmentsInvestmentsinSignificantPartnershipsandJointVenturesDetails"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/LongterminvestmentsInvestmentsinSignificantPartnershipsandJointVenturesDetails" xlink:type="extended" id="id3cb04b5f78e40e4b43b5f232cc5353d_LongterminvestmentsInvestmentsinSignificantPartnershipsandJointVenturesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_df54fea7-d320-4ee7-9ec9-939b981cd2ee" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_92c297a4-1837-4857-96cd-485e73a1de2c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_df54fea7-d320-4ee7-9ec9-939b981cd2ee" xlink:to="loc_us-gaap_Assets_92c297a4-1837-4857-96cd-485e73a1de2c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_3a051743-06b5-4a4a-9477-5f846ef9ddb9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_df54fea7-d320-4ee7-9ec9-939b981cd2ee" xlink:to="loc_us-gaap_Liabilities_3a051743-06b5-4a4a-9477-5f846ef9ddb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentUnderlyingEquityInNetAssets_d95e7070-10da-4cd7-a458-cfad9511156b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityMethodInvestmentUnderlyingEquityInNetAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_df54fea7-d320-4ee7-9ec9-939b981cd2ee" xlink:to="loc_us-gaap_EquityMethodInvestmentUnderlyingEquityInNetAssets_d95e7070-10da-4cd7-a458-cfad9511156b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity_94baf05b-6244-4f64-b124-bfbb6bc8fac4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_df54fea7-d320-4ee7-9ec9-939b981cd2ee" xlink:to="loc_us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity_94baf05b-6244-4f64-b124-bfbb6bc8fac4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments_bb654912-634d-45ce-84b2-ca601556c469" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_df54fea7-d320-4ee7-9ec9-939b981cd2ee" xlink:to="loc_us-gaap_EquityMethodInvestments_bb654912-634d-45ce-84b2-ca601556c469" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_7516d09e-2de2-4601-be41-88c4f890b404" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_df54fea7-d320-4ee7-9ec9-939b981cd2ee" xlink:to="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_7516d09e-2de2-4601-be41-88c4f890b404" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_5cc596ed-1ca9-4f70-aa84-a53ad4e28921" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_7516d09e-2de2-4601-be41-88c4f890b404" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_5cc596ed-1ca9-4f70-aa84-a53ad4e28921" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_5cc596ed-1ca9-4f70-aa84-a53ad4e28921_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_5cc596ed-1ca9-4f70-aa84-a53ad4e28921" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_5cc596ed-1ca9-4f70-aa84-a53ad4e28921_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_2ade3a05-0f2d-4b76-a9fa-21d217150a58" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_5cc596ed-1ca9-4f70-aa84-a53ad4e28921" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_2ade3a05-0f2d-4b76-a9fa-21d217150a58" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_InvestmentsinSignificantPartnershipsandJointVenturesMember_d3fed463-eb01-4dfd-a4f7-80624d88d476" xlink:href="aqunf-20210630.xsd#aqunf_InvestmentsinSignificantPartnershipsandJointVenturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_2ade3a05-0f2d-4b76-a9fa-21d217150a58" xlink:to="loc_aqunf_InvestmentsinSignificantPartnershipsandJointVenturesMember_d3fed463-eb01-4dfd-a4f7-80624d88d476" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_9d5592bc-3760-47d5-9e1c-51d0f521a339" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable_7516d09e-2de2-4601-be41-88c4f890b404" xlink:to="loc_dei_LegalEntityAxis_9d5592bc-3760-47d5-9e1c-51d0f521a339" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_9d5592bc-3760-47d5-9e1c-51d0f521a339_default" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_9d5592bc-3760-47d5-9e1c-51d0f521a339" xlink:to="loc_dei_EntityDomain_9d5592bc-3760-47d5-9e1c-51d0f521a339_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_9a32aa28-c09b-46f1-868e-15c9022c744c" xlink:href="https://xbrl.sec.gov/dei/2021/dei-2021.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_9d5592bc-3760-47d5-9e1c-51d0f521a339" xlink:to="loc_dei_EntityDomain_9a32aa28-c09b-46f1-868e-15c9022c744c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_APUCMember_d9ef9563-ab01-464f-92d8-960cbf72319a" xlink:href="aqunf-20210630.xsd#aqunf_APUCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_9a32aa28-c09b-46f1-868e-15c9022c744c" xlink:to="loc_aqunf_APUCMember_d9ef9563-ab01-464f-92d8-960cbf72319a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/LongterminvestmentsCombinedInformationforAPUCsinterestinVIEsDetails" xlink:type="simple" xlink:href="aqunf-20210630.xsd#LongterminvestmentsCombinedInformationforAPUCsinterestinVIEsDetails"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/LongterminvestmentsCombinedInformationforAPUCsinterestinVIEsDetails" xlink:type="extended" id="i68bc67da469f4cbdb9b53c3baafb7c6e_LongterminvestmentsCombinedInformationforAPUCsinterestinVIEsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityLineItems_c7bc00b9-67b5-42cd-8108-12c0619ba14a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableInterestEntityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsNet_f7d44f61-7e9e-4bd9-a001-ff84862717f0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c7bc00b9-67b5-42cd-8108-12c0619ba14a" xlink:to="loc_us-gaap_AssetsNet_f7d44f61-7e9e-4bd9-a001-ff84862717f0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesReceivableNet_d6e40b0e-745d-4ef8-936a-df79ad3cf3b5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NotesReceivableNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c7bc00b9-67b5-42cd-8108-12c0619ba14a" xlink:to="loc_us-gaap_NotesReceivableNet_d6e40b0e-745d-4ef8-936a-df79ad3cf3b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_VariableInterestEntitiesCommitmentsonBehalfofVIE_d416b44b-d200-4b51-b427-9de42c90a4fc" xlink:href="aqunf-20210630.xsd#aqunf_VariableInterestEntitiesCommitmentsonBehalfofVIE"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c7bc00b9-67b5-42cd-8108-12c0619ba14a" xlink:to="loc_aqunf_VariableInterestEntitiesCommitmentsonBehalfofVIE_d416b44b-d200-4b51-b427-9de42c90a4fc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount_0eb41479-8020-4f19-a341-c9398d19420d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c7bc00b9-67b5-42cd-8108-12c0619ba14a" xlink:to="loc_us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount_0eb41479-8020-4f19-a341-c9398d19420d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_56fcf7a1-4bb7-41a8-a695-8b8f3d708dfa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c7bc00b9-67b5-42cd-8108-12c0619ba14a" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_56fcf7a1-4bb7-41a8-a695-8b8f3d708dfa" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_2bdd4b7d-4a03-4ba4-9ea0-c672a4d2e725" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfVariableInterestEntitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_VariableInterestEntityLineItems_c7bc00b9-67b5-42cd-8108-12c0619ba14a" xlink:to="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_2bdd4b7d-4a03-4ba4-9ea0-c672a4d2e725" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis_3b166191-51d7-449d-9c8b-af56963ed4b4" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidatedEntitiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_2bdd4b7d-4a03-4ba4-9ea0-c672a4d2e725" xlink:to="loc_srt_ConsolidatedEntitiesAxis_3b166191-51d7-449d-9c8b-af56963ed4b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_3b166191-51d7-449d-9c8b-af56963ed4b4_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidatedEntitiesAxis_3b166191-51d7-449d-9c8b-af56963ed4b4" xlink:to="loc_srt_ConsolidatedEntitiesDomain_3b166191-51d7-449d-9c8b-af56963ed4b4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain_d9d6515a-e5fc-45a8-a03e-315c34cc93f3" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidatedEntitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidatedEntitiesAxis_3b166191-51d7-449d-9c8b-af56963ed4b4" xlink:to="loc_srt_ConsolidatedEntitiesDomain_d9d6515a-e5fc-45a8-a03e-315c34cc93f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember_2b5823f1-374b-44b0-866d-ef43ea4903d9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidatedEntitiesDomain_d9d6515a-e5fc-45a8-a03e-315c34cc93f3" xlink:to="loc_us-gaap_VariableInterestEntityNotPrimaryBeneficiaryMember_2b5823f1-374b-44b0-866d-ef43ea4903d9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_f41ba118-80f3-4a83-906c-3cc1a1894f99" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_2bdd4b7d-4a03-4ba4-9ea0-c672a4d2e725" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_f41ba118-80f3-4a83-906c-3cc1a1894f99" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_f41ba118-80f3-4a83-906c-3cc1a1894f99_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_f41ba118-80f3-4a83-906c-3cc1a1894f99" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_f41ba118-80f3-4a83-906c-3cc1a1894f99_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_3c49a77f-aebb-4a9c-a0c1-30b13c5bebb3" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_f41ba118-80f3-4a83-906c-3cc1a1894f99" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_3c49a77f-aebb-4a9c-a0c1-30b13c5bebb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SanAntonioWaterSystemMember_46cf3b3d-5e07-4588-9d34-1bf6cfa802b8" xlink:href="aqunf-20210630.xsd#aqunf_SanAntonioWaterSystemMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_3c49a77f-aebb-4a9c-a0c1-30b13c5bebb3" xlink:to="loc_aqunf_SanAntonioWaterSystemMember_46cf3b3d-5e07-4588-9d34-1bf6cfa802b8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_04142c1d-c233-4b95-90d2-8a3dc1b119e4" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable_2bdd4b7d-4a03-4ba4-9ea0-c672a4d2e725" xlink:to="loc_srt_OwnershipAxis_04142c1d-c233-4b95-90d2-8a3dc1b119e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_04142c1d-c233-4b95-90d2-8a3dc1b119e4_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_04142c1d-c233-4b95-90d2-8a3dc1b119e4" xlink:to="loc_srt_OwnershipDomain_04142c1d-c233-4b95-90d2-8a3dc1b119e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_d7b3753e-7089-4400-8167-6fe1eaab09c0" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_04142c1d-c233-4b95-90d2-8a3dc1b119e4" xlink:to="loc_srt_OwnershipDomain_d7b3753e-7089-4400-8167-6fe1eaab09c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_APUCMember_451f6c15-b91d-4300-8620-d9c67efee5d5" xlink:href="aqunf-20210630.xsd#aqunf_APUCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_d7b3753e-7089-4400-8167-6fe1eaab09c0" xlink:to="loc_aqunf_APUCMember_451f6c15-b91d-4300-8620-d9c67efee5d5" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/LongtermdebtScheduleofLongtermDebtDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#LongtermdebtScheduleofLongtermDebtDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/LongtermdebtScheduleofLongtermDebtDetail" xlink:type="extended" id="if9e30417a60b4c89970ff211c2c8f1c4_LongtermdebtScheduleofLongtermDebtDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_a75b19ea-c6bc-4881-a65b-2618494081d0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_d1678035-f342-4d55-8223-a776a793601c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a75b19ea-c6bc-4881-a65b-2618494081d0" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_d1678035-f342-4d55-8223-a776a793601c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_8f12a4b5-0b46-4286-9ffc-4b70e38d128f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a75b19ea-c6bc-4881-a65b-2618494081d0" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_8f12a4b5-0b46-4286-9ffc-4b70e38d128f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_a25db7d7-67b7-4000-9c5c-2b280c1e90b1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a75b19ea-c6bc-4881-a65b-2618494081d0" xlink:to="loc_us-gaap_LongTermDebt_a25db7d7-67b7-4000-9c5c-2b280c1e90b1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_ed6cdc71-7b5e-48d8-8385-3fc84736d219" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a75b19ea-c6bc-4881-a65b-2618494081d0" xlink:to="loc_us-gaap_LongTermDebtCurrent_ed6cdc71-7b5e-48d8-8385-3fc84736d219" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_cd4b722a-aa7d-4cbd-8f00-0a1cc56511a5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a75b19ea-c6bc-4881-a65b-2618494081d0" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_cd4b722a-aa7d-4cbd-8f00-0a1cc56511a5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_dfb87cdb-6212-44d4-951c-525c5688cc22" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a75b19ea-c6bc-4881-a65b-2618494081d0" xlink:to="loc_us-gaap_DebtInstrumentTable_dfb87cdb-6212-44d4-951c-525c5688cc22" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_863b5306-befd-4be6-b843-4c7489bfa01a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_dfb87cdb-6212-44d4-951c-525c5688cc22" xlink:to="loc_us-gaap_CreditFacilityAxis_863b5306-befd-4be6-b843-4c7489bfa01a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_863b5306-befd-4be6-b843-4c7489bfa01a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_863b5306-befd-4be6-b843-4c7489bfa01a" xlink:to="loc_us-gaap_CreditFacilityDomain_863b5306-befd-4be6-b843-4c7489bfa01a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_8c245b5e-e138-419c-aba1-83e9ebccaecc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_863b5306-befd-4be6-b843-4c7489bfa01a" xlink:to="loc_us-gaap_CreditFacilityDomain_8c245b5e-e138-419c-aba1-83e9ebccaecc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_532afc57-9180-4122-b2ad-bfded9d1c35a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_8c245b5e-e138-419c-aba1-83e9ebccaecc" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_532afc57-9180-4122-b2ad-bfded9d1c35a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_1f80b472-6195-414c-bb73-be6be6e2ec72" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_dfb87cdb-6212-44d4-951c-525c5688cc22" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_1f80b472-6195-414c-bb73-be6be6e2ec72" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_1f80b472-6195-414c-bb73-be6be6e2ec72_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_1f80b472-6195-414c-bb73-be6be6e2ec72" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_1f80b472-6195-414c-bb73-be6be6e2ec72_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_afed6549-ab55-455e-b80a-977e748d00ab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_1f80b472-6195-414c-bb73-be6be6e2ec72" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_afed6549-ab55-455e-b80a-977e748d00ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnsecuredDebtMember_58919964-c30c-4393-9568-ed0d289235ce" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnsecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_afed6549-ab55-455e-b80a-977e748d00ab" xlink:to="loc_us-gaap_UnsecuredDebtMember_58919964-c30c-4393-9568-ed0d289235ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_962089a4-5659-49be-aba0-56a8af17fb0a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_afed6549-ab55-455e-b80a-977e748d00ab" xlink:to="loc_us-gaap_SecuredDebtMember_962089a4-5659-49be-aba0-56a8af17fb0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_509b6053-235c-475b-97c1-32ae365a4cd2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_afed6549-ab55-455e-b80a-977e748d00ab" xlink:to="loc_us-gaap_SeniorNotesMember_509b6053-235c-475b-97c1-32ae365a4cd2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_35a68c57-5e7a-4361-9f05-3068b5cef981" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_dfb87cdb-6212-44d4-951c-525c5688cc22" xlink:to="loc_us-gaap_DebtInstrumentAxis_35a68c57-5e7a-4361-9f05-3068b5cef981" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_35a68c57-5e7a-4361-9f05-3068b5cef981_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_35a68c57-5e7a-4361-9f05-3068b5cef981" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_35a68c57-5e7a-4361-9f05-3068b5cef981_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_b8b9f4b1-cb65-4e33-8329-96d2a02ad58d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_35a68c57-5e7a-4361-9f05-3068b5cef981" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_b8b9f4b1-cb65-4e33-8329-96d2a02ad58d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SeniorUnsecuredRevolvingCreditFacilitiesMember_031897fb-e379-419d-bca9-1912347a55b8" xlink:href="aqunf-20210630.xsd#aqunf_SeniorUnsecuredRevolvingCreditFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8b9f4b1-cb65-4e33-8329-96d2a02ad58d" xlink:to="loc_aqunf_SeniorUnsecuredRevolvingCreditFacilitiesMember_031897fb-e379-419d-bca9-1912347a55b8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SeniorUnsecuredBankCreditFacilitiesMember_cfc1c4a6-c900-40c0-ba4e-2fcf3e041248" xlink:href="aqunf-20210630.xsd#aqunf_SeniorUnsecuredBankCreditFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8b9f4b1-cb65-4e33-8329-96d2a02ad58d" xlink:to="loc_aqunf_SeniorUnsecuredBankCreditFacilitiesMember_cfc1c4a6-c900-40c0-ba4e-2fcf3e041248" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_645c34cc-c010-4964-8800-db156c69ac3b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8b9f4b1-cb65-4e33-8329-96d2a02ad58d" xlink:to="loc_us-gaap_CommercialPaperMember_645c34cc-c010-4964-8800-db156c69ac3b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_USDollarSeniorUnsecuredNotesGreenEquityUnitsMember_674208e3-aa77-4394-8759-5289b935e7f9" xlink:href="aqunf-20210630.xsd#aqunf_USDollarSeniorUnsecuredNotesGreenEquityUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8b9f4b1-cb65-4e33-8329-96d2a02ad58d" xlink:to="loc_aqunf_USDollarSeniorUnsecuredNotesGreenEquityUnitsMember_674208e3-aa77-4394-8759-5289b935e7f9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_U.SDollarSeniorUnsecuredNotesMember_467bb812-0273-45a0-a738-595f3b5d3a08" xlink:href="aqunf-20210630.xsd#aqunf_U.SDollarSeniorUnsecuredNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8b9f4b1-cb65-4e33-8329-96d2a02ad58d" xlink:to="loc_aqunf_U.SDollarSeniorUnsecuredNotesMember_467bb812-0273-45a0-a738-595f3b5d3a08" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_U.S.DollarSeniorUnsecuredUtilityNotesMember_428bbde9-5d11-4fdc-858e-2e4fc0241a9a" xlink:href="aqunf-20210630.xsd#aqunf_U.S.DollarSeniorUnsecuredUtilityNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8b9f4b1-cb65-4e33-8329-96d2a02ad58d" xlink:to="loc_aqunf_U.S.DollarSeniorUnsecuredUtilityNotesMember_428bbde9-5d11-4fdc-858e-2e4fc0241a9a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_U.S.DollarSeniorUnsecuredUtilityBondsMember_f4592ab1-16e0-47f5-ba84-7a6c635fb71c" xlink:href="aqunf-20210630.xsd#aqunf_U.S.DollarSeniorUnsecuredUtilityBondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8b9f4b1-cb65-4e33-8329-96d2a02ad58d" xlink:to="loc_aqunf_U.S.DollarSeniorUnsecuredUtilityBondsMember_f4592ab1-16e0-47f5-ba84-7a6c635fb71c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CanadianDollarSeniorUnsecuredNotesMember_ceeedceb-d9df-4475-a975-a929495849f5" xlink:href="aqunf-20210630.xsd#aqunf_CanadianDollarSeniorUnsecuredNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8b9f4b1-cb65-4e33-8329-96d2a02ad58d" xlink:to="loc_aqunf_CanadianDollarSeniorUnsecuredNotesMember_ceeedceb-d9df-4475-a975-a929495849f5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CanadianDollarSeniorSecuredProjectsNotesMember_120eacee-d2c4-4e72-b4b9-028fe36c911b" xlink:href="aqunf-20210630.xsd#aqunf_CanadianDollarSeniorSecuredProjectsNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8b9f4b1-cb65-4e33-8329-96d2a02ad58d" xlink:to="loc_aqunf_CanadianDollarSeniorSecuredProjectsNotesMember_120eacee-d2c4-4e72-b4b9-028fe36c911b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ChileanSeniorUnsecuredUtilityNotesMember_af6fa0ba-5fbb-4ad6-bd5c-1dfc06e1a7dd" xlink:href="aqunf-20210630.xsd#aqunf_ChileanSeniorUnsecuredUtilityNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8b9f4b1-cb65-4e33-8329-96d2a02ad58d" xlink:to="loc_aqunf_ChileanSeniorUnsecuredUtilityNotesMember_af6fa0ba-5fbb-4ad6-bd5c-1dfc06e1a7dd" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SeniorUnsecuredDebtMember_aabe5a31-2c4a-409e-9ca1-e58538727aea" xlink:href="aqunf-20210630.xsd#aqunf_SeniorUnsecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8b9f4b1-cb65-4e33-8329-96d2a02ad58d" xlink:to="loc_aqunf_SeniorUnsecuredDebtMember_aabe5a31-2c4a-409e-9ca1-e58538727aea" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_U.S.DollarSubordinatedUnsecuredNotesMember_de3fc1cd-e36d-46e0-a1b9-89b74db8335a" xlink:href="aqunf-20210630.xsd#aqunf_U.S.DollarSubordinatedUnsecuredNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b8b9f4b1-cb65-4e33-8329-96d2a02ad58d" xlink:to="loc_aqunf_U.S.DollarSubordinatedUnsecuredNotesMember_de3fc1cd-e36d-46e0-a1b9-89b74db8335a" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/LongtermdebtNarrativeDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#LongtermdebtNarrativeDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/LongtermdebtNarrativeDetail" xlink:type="extended" id="iecd38f67b7ab4dc999180f5107d80446_LongtermdebtNarrativeDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermBorrowings_aec90c7a-585d-4bfc-a6ee-602a27b5e2f3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShortTermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_us-gaap_ShortTermBorrowings_aec90c7a-585d-4bfc-a6ee-602a27b5e2f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesIssued_5905ae36-9181-4f6c-bff4-328e4bc5fc85" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquitySharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_us-gaap_TemporaryEquitySharesIssued_5905ae36-9181-4f6c-bff4-328e4bc5fc85" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromConvertibleDebt_86b95aa9-f52e-4c5c-97e1-8b7d15ffb65b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromConvertibleDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_us-gaap_ProceedsFromConvertibleDebt_86b95aa9-f52e-4c5c-97e1-8b7d15ffb65b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityParOrStatedValuePerShare_82acd573-0f05-4dfd-9a91-02961f49bf3a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_us-gaap_TemporaryEquityParOrStatedValuePerShare_82acd573-0f05-4dfd-9a91-02961f49bf3a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_TemporaryEquityBeneficialOwnershipInterestPercent_f239070d-bf26-46d3-9d5f-37c8679bc721" xlink:href="aqunf-20210630.xsd#aqunf_TemporaryEquityBeneficialOwnershipInterestPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_aqunf_TemporaryEquityBeneficialOwnershipInterestPercent_f239070d-bf26-46d3-9d5f-37c8679bc721" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_TemporaryEquityDividendRatePercentage_8db259f0-d5d1-41dd-b305-ffa08f4a0e5a" xlink:href="aqunf-20210630.xsd#aqunf_TemporaryEquityDividendRatePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_aqunf_TemporaryEquityDividendRatePercentage_8db259f0-d5d1-41dd-b305-ffa08f4a0e5a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_15cb4d7b-bb14-4157-9ac0-a10ea5e9c35d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_15cb4d7b-bb14-4157-9ac0-a10ea5e9c35d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_TemporaryEquitySharePurchaseContractInterestRate_95550a99-dee5-43ef-8106-161a0653e52a" xlink:href="aqunf-20210630.xsd#aqunf_TemporaryEquitySharePurchaseContractInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_aqunf_TemporaryEquitySharePurchaseContractInterestRate_95550a99-dee5-43ef-8106-161a0653e52a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ContractAdjustmentPaymentsExcludingInterest_d5f7bc1c-0c7b-4a75-a327-b4f22a94d3b7" xlink:href="aqunf-20210630.xsd#aqunf_ContractAdjustmentPaymentsExcludingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_aqunf_ContractAdjustmentPaymentsExcludingInterest_d5f7bc1c-0c7b-4a75-a327-b4f22a94d3b7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ContractAdjustmentPaymentsAccretionPeriod_0d050dda-8393-4c16-9c60-ccca3310b093" xlink:href="aqunf-20210630.xsd#aqunf_ContractAdjustmentPaymentsAccretionPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_aqunf_ContractAdjustmentPaymentsAccretionPeriod_0d050dda-8393-4c16-9c60-ccca3310b093" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DebtInstrumentConvertibleNumberOfTradingDaysIncludedInAveragePriceOfCommonShares_e5f12f6d-ee4a-49f1-b24d-aa936989f21d" xlink:href="aqunf-20210630.xsd#aqunf_DebtInstrumentConvertibleNumberOfTradingDaysIncludedInAveragePriceOfCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_aqunf_DebtInstrumentConvertibleNumberOfTradingDaysIncludedInAveragePriceOfCommonShares_e5f12f6d-ee4a-49f1-b24d-aa936989f21d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionRatio1_c9c91e9b-646a-4e3a-b0cb-91f21f2413bc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentConvertibleConversionRatio1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionRatio1_c9c91e9b-646a-4e3a-b0cb-91f21f2413bc" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_TemporaryEquityThresholdAppreciationPricePerShare_896d0d0a-eff2-454c-843d-d8834cb75d81" xlink:href="aqunf-20210630.xsd#aqunf_TemporaryEquityThresholdAppreciationPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_aqunf_TemporaryEquityThresholdAppreciationPricePerShare_896d0d0a-eff2-454c-843d-d8834cb75d81" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_TemporaryEquityMaximumSettlementRate_c14eed46-ae05-4d2b-ae6d-5f9197d19789" xlink:href="aqunf-20210630.xsd#aqunf_TemporaryEquityMaximumSettlementRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_aqunf_TemporaryEquityMaximumSettlementRate_c14eed46-ae05-4d2b-ae6d-5f9197d19789" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_TemporaryEquityPricePerShareIncludedInMaximumSettlementRateCalculation_7a3cd54f-9352-4483-a2a5-5a5bb1dbf459" xlink:href="aqunf-20210630.xsd#aqunf_TemporaryEquityPricePerShareIncludedInMaximumSettlementRateCalculation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_aqunf_TemporaryEquityPricePerShareIncludedInMaximumSettlementRateCalculation_7a3cd54f-9352-4483-a2a5-5a5bb1dbf459" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ExtinguishmentOfDebtAmount_9cc9fb0e-a0d8-448a-8445-587ff1e1e13b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ExtinguishmentOfDebtAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_us-gaap_ExtinguishmentOfDebtAmount_9cc9fb0e-a0d8-448a-8445-587ff1e1e13b" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_7da2b7b7-7a2c-450e-ab59-aebdd4966f74" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_7da2b7b7-7a2c-450e-ab59-aebdd4966f74" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_dd8f5cbb-bc03-4f90-825e-7f9804626dd1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_dd8f5cbb-bc03-4f90-825e-7f9804626dd1" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DebtInstrumentIssuedBelowParAmount_bdb65e8a-f847-41fd-9df8-e097a8925e50" xlink:href="aqunf-20210630.xsd#aqunf_DebtInstrumentIssuedBelowParAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_aqunf_DebtInstrumentIssuedBelowParAmount_bdb65e8a-f847-41fd-9df8-e097a8925e50" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_c73985d9-78a6-4ec0-89bd-4a66440d80d8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6fc48a66-0289-44e2-b737-2f2f59f11146" xlink:to="loc_us-gaap_DebtInstrumentTable_c73985d9-78a6-4ec0-89bd-4a66440d80d8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_93edc3d9-5707-4ff8-8510-33945ab6b22c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_c73985d9-78a6-4ec0-89bd-4a66440d80d8" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_93edc3d9-5707-4ff8-8510-33945ab6b22c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_93edc3d9-5707-4ff8-8510-33945ab6b22c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_93edc3d9-5707-4ff8-8510-33945ab6b22c" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_93edc3d9-5707-4ff8-8510-33945ab6b22c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_5c02ab12-d36e-4b80-a625-a26dc85a0eb3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_93edc3d9-5707-4ff8-8510-33945ab6b22c" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_5c02ab12-d36e-4b80-a625-a26dc85a0eb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnsecuredDebtMember_054f26f6-3d9a-4903-8e07-52fe20dd655e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnsecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_5c02ab12-d36e-4b80-a625-a26dc85a0eb3" xlink:to="loc_us-gaap_UnsecuredDebtMember_054f26f6-3d9a-4903-8e07-52fe20dd655e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_06f4d5c5-dabc-4922-a122-5dbf8059262e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_c73985d9-78a6-4ec0-89bd-4a66440d80d8" xlink:to="loc_us-gaap_DebtInstrumentAxis_06f4d5c5-dabc-4922-a122-5dbf8059262e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_06f4d5c5-dabc-4922-a122-5dbf8059262e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_06f4d5c5-dabc-4922-a122-5dbf8059262e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_06f4d5c5-dabc-4922-a122-5dbf8059262e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_6531c2b8-353a-40c9-9bd4-bcedb7420488" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_06f4d5c5-dabc-4922-a122-5dbf8059262e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_6531c2b8-353a-40c9-9bd4-bcedb7420488" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_USDollarSeniorUnsecuredNotesGreenEquityUnitsMember_975959e6-13b4-44df-a667-5db6bf0f0608" xlink:href="aqunf-20210630.xsd#aqunf_USDollarSeniorUnsecuredNotesGreenEquityUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_6531c2b8-353a-40c9-9bd4-bcedb7420488" xlink:to="loc_aqunf_USDollarSeniorUnsecuredNotesGreenEquityUnitsMember_975959e6-13b4-44df-a667-5db6bf0f0608" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CanadianDollarSeniorUnsecuredNotesMember_1e4fd9ac-e775-46bf-95da-d65a313d96fe" xlink:href="aqunf-20210630.xsd#aqunf_CanadianDollarSeniorUnsecuredNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_6531c2b8-353a-40c9-9bd4-bcedb7420488" xlink:to="loc_aqunf_CanadianDollarSeniorUnsecuredNotesMember_1e4fd9ac-e775-46bf-95da-d65a313d96fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CanadianDollarSeniorUnsecuredDebenturesMember_bdab8b10-dad9-4281-a2a8-640653eab627" xlink:href="aqunf-20210630.xsd#aqunf_CanadianDollarSeniorUnsecuredDebenturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_6531c2b8-353a-40c9-9bd4-bcedb7420488" xlink:to="loc_aqunf_CanadianDollarSeniorUnsecuredDebenturesMember_bdab8b10-dad9-4281-a2a8-640653eab627" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/PensionandotherpostretirementbenefitsComponentsofNetBenefitCostsforPensionPlansandOPEBRecordedasPartofAdministrativeExpensesDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#PensionandotherpostretirementbenefitsComponentsofNetBenefitCostsforPensionPlansandOPEBRecordedasPartofAdministrativeExpensesDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/PensionandotherpostretirementbenefitsComponentsofNetBenefitCostsforPensionPlansandOPEBRecordedasPartofAdministrativeExpensesDetail" xlink:type="extended" id="ibabbff9962e7483193d2456d71324671_PensionandotherpostretirementbenefitsComponentsofNetBenefitCostsforPensionPlansandOPEBRecordedasPartofAdministrativeExpensesDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_99af95f0-735f-4afa-ac40-656814685dcb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_5e35637b-b8fc-4ff2-b06b-415f592ebd4d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_99af95f0-735f-4afa-ac40-656814685dcb" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_5e35637b-b8fc-4ff2-b06b-415f592ebd4d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DefinedBenefitPlanNonserviceCostsAbstract_e1192b02-7ffe-4794-90c6-c1a37d76c2fd" xlink:href="aqunf-20210630.xsd#aqunf_DefinedBenefitPlanNonserviceCostsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_99af95f0-735f-4afa-ac40-656814685dcb" xlink:to="loc_aqunf_DefinedBenefitPlanNonserviceCostsAbstract_e1192b02-7ffe-4794-90c6-c1a37d76c2fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_dfee4073-f49d-45bf-a592-c23274cf164d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_DefinedBenefitPlanNonserviceCostsAbstract_e1192b02-7ffe-4794-90c6-c1a37d76c2fd" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_dfee4073-f49d-45bf-a592-c23274cf164d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_7a31bb69-5bde-4b97-93ad-418569f61f44" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_DefinedBenefitPlanNonserviceCostsAbstract_e1192b02-7ffe-4794-90c6-c1a37d76c2fd" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_7a31bb69-5bde-4b97-93ad-418569f61f44" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_ddb3dfab-75d1-4488-9ace-1dbc7db3f0c3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_DefinedBenefitPlanNonserviceCostsAbstract_e1192b02-7ffe-4794-90c6-c1a37d76c2fd" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_ddb3dfab-75d1-4488-9ace-1dbc7db3f0c3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_7a0cfb21-9346-4090-819c-15bc46a30a0a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_DefinedBenefitPlanNonserviceCostsAbstract_e1192b02-7ffe-4794-90c6-c1a37d76c2fd" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_7a0cfb21-9346-4090-819c-15bc46a30a0a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DefinedBenefitPlanAmortizationOfRegulatoryAssetsandLiabilities_199deee3-e2c1-4a56-8468-e7a348c76d9b" xlink:href="aqunf-20210630.xsd#aqunf_DefinedBenefitPlanAmortizationOfRegulatoryAssetsandLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_DefinedBenefitPlanNonserviceCostsAbstract_e1192b02-7ffe-4794-90c6-c1a37d76c2fd" xlink:to="loc_aqunf_DefinedBenefitPlanAmortizationOfRegulatoryAssetsandLiabilities_199deee3-e2c1-4a56-8468-e7a348c76d9b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DefinedBenefitPlanNonserviceCostsTotal_29c00342-675a-4de6-ac55-cc4721198f72" xlink:href="aqunf-20210630.xsd#aqunf_DefinedBenefitPlanNonserviceCostsTotal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_99af95f0-735f-4afa-ac40-656814685dcb" xlink:to="loc_aqunf_DefinedBenefitPlanNonserviceCostsTotal_29c00342-675a-4de6-ac55-cc4721198f72" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_1de36279-22f8-4a5e-9357-54f29edefb70" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_99af95f0-735f-4afa-ac40-656814685dcb" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_1de36279-22f8-4a5e-9357-54f29edefb70" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_14a72149-9e60-4a0d-8c17-c68b9adb0fb2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_99af95f0-735f-4afa-ac40-656814685dcb" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_14a72149-9e60-4a0d-8c17-c68b9adb0fb2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_0a2b394f-5163-4828-8ee1-d39483d88554" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_14a72149-9e60-4a0d-8c17-c68b9adb0fb2" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_0a2b394f-5163-4828-8ee1-d39483d88554" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_0a2b394f-5163-4828-8ee1-d39483d88554_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_0a2b394f-5163-4828-8ee1-d39483d88554" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_0a2b394f-5163-4828-8ee1-d39483d88554_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_e4336f14-b558-4459-8654-1dcc9a06ca5b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_0a2b394f-5163-4828-8ee1-d39483d88554" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_e4336f14-b558-4459-8654-1dcc9a06ca5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_f7ffd1d0-f742-427b-aab4-f0657715ff23" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_e4336f14-b558-4459-8654-1dcc9a06ca5b" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_f7ffd1d0-f742-427b-aab4-f0657715ff23" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_452812c5-e58a-4ed2-ab24-bb0d5b0830bf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_e4336f14-b558-4459-8654-1dcc9a06ca5b" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_452812c5-e58a-4ed2-ab24-bb0d5b0830bf" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/ShareholderscapitalAdditionalInformationDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#ShareholderscapitalAdditionalInformationDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/ShareholderscapitalAdditionalInformationDetail" xlink:type="extended" id="if6a5a5da9c254a0f99ee9aee572a2a16_ShareholderscapitalAdditionalInformationDetail">
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:href="aqunf-20210630.xsd#aqunf_StockholdersEquityNoteLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_TreasuryStockAmountReservedForIssuanceUnderThePlan_6e76d9b2-0f14-45f3-858d-cad7d8173d3e" xlink:href="aqunf-20210630.xsd#aqunf_TreasuryStockAmountReservedForIssuanceUnderThePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_aqunf_TreasuryStockAmountReservedForIssuanceUnderThePlan_6e76d9b2-0f14-45f3-858d-cad7d8173d3e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_e16159bb-36d8-4775-a7a6-4310395ceebc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_e16159bb-36d8-4775-a7a6-4310395ceebc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SaleOfStockAveragePricePerShare_352f95c3-878a-4d24-b44e-a3b1687776e4" xlink:href="aqunf-20210630.xsd#aqunf_SaleOfStockAveragePricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_aqunf_SaleOfStockAveragePricePerShare_352f95c3-878a-4d24-b44e-a3b1687776e4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SaleOfStockConsiderationReceivedOnTransactionGross_6b96a03a-251c-4d2e-965c-d2ad49b605e7" xlink:href="aqunf-20210630.xsd#aqunf_SaleOfStockConsiderationReceivedOnTransactionGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_aqunf_SaleOfStockConsiderationReceivedOnTransactionGross_6b96a03a-251c-4d2e-965c-d2ad49b605e7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SaleOfStockConsiderationReceivedOnTransactionNetofCommissions_bab96fc3-45f9-478d-b0f3-1b7aab9e0cfd" xlink:href="aqunf-20210630.xsd#aqunf_SaleOfStockConsiderationReceivedOnTransactionNetofCommissions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_aqunf_SaleOfStockConsiderationReceivedOnTransactionNetofCommissions_bab96fc3-45f9-478d-b0f3-1b7aab9e0cfd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SaleofStockOtherRelatedcosts_4d14f4b8-cf7d-4e9f-b0e9-8bdb3eab8c5e" xlink:href="aqunf-20210630.xsd#aqunf_SaleofStockOtherRelatedcosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_aqunf_SaleofStockOtherRelatedcosts_4d14f4b8-cf7d-4e9f-b0e9-8bdb3eab8c5e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_810992b3-42ac-41a9-bb86-3828800ab903" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_810992b3-42ac-41a9-bb86-3828800ab903" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_a97c2c45-808c-40c1-b8df-d445f3e841eb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_a97c2c45-808c-40c1-b8df-d445f3e841eb" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_6e24a0e8-92fe-43e7-a688-7f41a6a6ab1d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_6e24a0e8-92fe-43e7-a688-7f41a6a6ab1d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_0b966650-7392-4f5f-b753-c62a181f7f20" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_0b966650-7392-4f5f-b753-c62a181f7f20" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ShareBasedCompensationArrangementByShareBasedPaymentAwardWeightedAverageGrantDateFairValue_5b6c0056-dc95-4a29-87d5-99e8b262d61d" xlink:href="aqunf-20210630.xsd#aqunf_ShareBasedCompensationArrangementByShareBasedPaymentAwardWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_aqunf_ShareBasedCompensationArrangementByShareBasedPaymentAwardWeightedAverageGrantDateFairValue_5b6c0056-dc95-4a29-87d5-99e8b262d61d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_c5c18c74-2217-4540-b4d2-3be84bc32bf5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_c5c18c74-2217-4540-b4d2-3be84bc32bf5" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_8a5b14a1-2303-44b2-aead-6bedce94a4a9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_8a5b14a1-2303-44b2-aead-6bedce94a4a9" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_4cc5097b-74db-4671-a72c-29c7a18fe638" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_4cc5097b-74db-4671-a72c-29c7a18fe638" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_7780995d-3152-4c23-b826-b29e23ae6b66" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_7780995d-3152-4c23-b826-b29e23ae6b66" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_8bec0af5-5d74-400b-b862-cbdc977e00ef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_8bec0af5-5d74-400b-b862-cbdc977e00ef" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SharebasedPaymentArrangementSharesWithheldasPaymentfortheExercisePriceandforTaxWithholdingObligation_7c5e22ee-2afd-4827-825f-174408f6bbdf" xlink:href="aqunf-20210630.xsd#aqunf_SharebasedPaymentArrangementSharesWithheldasPaymentfortheExercisePriceandforTaxWithholdingObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_aqunf_SharebasedPaymentArrangementSharesWithheldasPaymentfortheExercisePriceandforTaxWithholdingObligation_7c5e22ee-2afd-4827-825f-174408f6bbdf" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_84d2b7d8-7b36-4cf9-a3a6-1acf8092b0ac" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_84d2b7d8-7b36-4cf9-a3a6-1acf8092b0ac" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_f279f280-02ab-4450-add9-3fd576fbd491" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_f279f280-02ab-4450-add9-3fd576fbd491" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_3eeb58f4-3d68-456e-8e47-9f168c9985be" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_us-gaap_CommonStockSharesIssued_3eeb58f4-3d68-456e-8e47-9f168c9985be" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_StockholdersEquityNoteTable_add8f061-fb33-4a81-921d-ad961c1aa464" xlink:href="aqunf-20210630.xsd#aqunf_StockholdersEquityNoteTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_aqunf_StockholdersEquityNoteLineItems_8aae544d-f6bd-4a7f-9bad-f7f7d1deb1eb" xlink:to="loc_aqunf_StockholdersEquityNoteTable_add8f061-fb33-4a81-921d-ad961c1aa464" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_15a48c7b-679f-49e0-a9d9-d2f83c49288e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_StockholdersEquityNoteTable_add8f061-fb33-4a81-921d-ad961c1aa464" xlink:to="loc_us-gaap_PlanNameAxis_15a48c7b-679f-49e0-a9d9-d2f83c49288e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_15a48c7b-679f-49e0-a9d9-d2f83c49288e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_15a48c7b-679f-49e0-a9d9-d2f83c49288e" xlink:to="loc_us-gaap_PlanNameDomain_15a48c7b-679f-49e0-a9d9-d2f83c49288e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_5236336d-831d-44b5-9c35-3aaecff5782a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_15a48c7b-679f-49e0-a9d9-d2f83c49288e" xlink:to="loc_us-gaap_PlanNameDomain_5236336d-831d-44b5-9c35-3aaecff5782a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ATMEquityProgramMember_5ca33452-4f2b-4a10-953b-495d0799a871" xlink:href="aqunf-20210630.xsd#aqunf_ATMEquityProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_5236336d-831d-44b5-9c35-3aaecff5782a" xlink:to="loc_aqunf_ATMEquityProgramMember_5ca33452-4f2b-4a10-953b-495d0799a871" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_8115042b-5932-457b-81fb-2678c0f40b9b" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_StockholdersEquityNoteTable_add8f061-fb33-4a81-921d-ad961c1aa464" xlink:to="loc_srt_TitleOfIndividualAxis_8115042b-5932-457b-81fb-2678c0f40b9b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_8115042b-5932-457b-81fb-2678c0f40b9b_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_8115042b-5932-457b-81fb-2678c0f40b9b" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_8115042b-5932-457b-81fb-2678c0f40b9b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_7c4e4363-36a9-4f35-a84f-2e8011f6374b" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_8115042b-5932-457b-81fb-2678c0f40b9b" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_7c4e4363-36a9-4f35-a84f-2e8011f6374b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ExecutiveOfficerMember_25d136c6-a710-4c2f-9a82-27718337d56f" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ExecutiveOfficerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_7c4e4363-36a9-4f35-a84f-2e8011f6374b" xlink:to="loc_srt_ExecutiveOfficerMember_25d136c6-a710-4c2f-9a82-27718337d56f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_20c2a3cd-0602-47bb-a4c8-c9c4c063363d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_StockholdersEquityNoteTable_add8f061-fb33-4a81-921d-ad961c1aa464" xlink:to="loc_us-gaap_AwardTypeAxis_20c2a3cd-0602-47bb-a4c8-c9c4c063363d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_20c2a3cd-0602-47bb-a4c8-c9c4c063363d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_20c2a3cd-0602-47bb-a4c8-c9c4c063363d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_20c2a3cd-0602-47bb-a4c8-c9c4c063363d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_88ee0e96-a77c-4e99-9bde-974c5c6266d4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_20c2a3cd-0602-47bb-a4c8-c9c4c063363d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_88ee0e96-a77c-4e99-9bde-974c5c6266d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_RSUsAndPSUsMember_62eca013-22d4-4ade-970a-b6c451d98212" xlink:href="aqunf-20210630.xsd#aqunf_RSUsAndPSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_88ee0e96-a77c-4e99-9bde-974c5c6266d4" xlink:to="loc_aqunf_RSUsAndPSUsMember_62eca013-22d4-4ade-970a-b6c451d98212" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_9457ea67-6c4c-447a-9a7e-edc4a979afea" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_88ee0e96-a77c-4e99-9bde-974c5c6266d4" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_9457ea67-6c4c-447a-9a7e-edc4a979afea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_BonusDeferralRestrictedStockUnitsMember_acdf2189-89dc-4c65-80c8-9364f8a957bc" xlink:href="aqunf-20210630.xsd#aqunf_BonusDeferralRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_88ee0e96-a77c-4e99-9bde-974c5c6266d4" xlink:to="loc_aqunf_BonusDeferralRestrictedStockUnitsMember_acdf2189-89dc-4c65-80c8-9364f8a957bc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DeferredShareUnitsMember_c5b4ed48-f96a-4a22-99f9-745cbde7ede6" xlink:href="aqunf-20210630.xsd#aqunf_DeferredShareUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_88ee0e96-a77c-4e99-9bde-974c5c6266d4" xlink:to="loc_aqunf_DeferredShareUnitsMember_c5b4ed48-f96a-4a22-99f9-745cbde7ede6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_f9deaf19-1441-4fc4-a37e-8329a3fb7700" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_StockholdersEquityNoteTable_add8f061-fb33-4a81-921d-ad961c1aa464" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_f9deaf19-1441-4fc4-a37e-8329a3fb7700" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_f9deaf19-1441-4fc4-a37e-8329a3fb7700_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_f9deaf19-1441-4fc4-a37e-8329a3fb7700" xlink:to="loc_us-gaap_EquityComponentDomain_f9deaf19-1441-4fc4-a37e-8329a3fb7700_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_3c8d821e-792a-4f3c-9eac-6ff7a23eaba1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_f9deaf19-1441-4fc4-a37e-8329a3fb7700" xlink:to="loc_us-gaap_EquityComponentDomain_3c8d821e-792a-4f3c-9eac-6ff7a23eaba1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_ba5d4e23-82f5-4ca4-9cb9-c24872299770" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_3c8d821e-792a-4f3c-9eac-6ff7a23eaba1" xlink:to="loc_us-gaap_TreasuryStockCommonMember_ba5d4e23-82f5-4ca4-9cb9-c24872299770" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_c0faa6f0-8ac2-4ac7-ad50-1e0a96b5c230" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_3c8d821e-792a-4f3c-9eac-6ff7a23eaba1" xlink:to="loc_us-gaap_CommonStockMember_c0faa6f0-8ac2-4ac7-ad50-1e0a96b5c230" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_00638518-eccd-4bca-9eb3-58f1351e398e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_StockholdersEquityNoteTable_add8f061-fb33-4a81-921d-ad961c1aa464" xlink:to="loc_us-gaap_VestingAxis_00638518-eccd-4bca-9eb3-58f1351e398e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_00638518-eccd-4bca-9eb3-58f1351e398e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_00638518-eccd-4bca-9eb3-58f1351e398e" xlink:to="loc_us-gaap_VestingDomain_00638518-eccd-4bca-9eb3-58f1351e398e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_eba2001e-7d66-49fa-8a13-3d8360ad61e0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_00638518-eccd-4bca-9eb3-58f1351e398e" xlink:to="loc_us-gaap_VestingDomain_eba2001e-7d66-49fa-8a13-3d8360ad61e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_c0b5845f-1343-4ec4-b525-461e420da341" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_eba2001e-7d66-49fa-8a13-3d8360ad61e0" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_c0b5845f-1343-4ec4-b525-461e420da341" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_a163db99-2d1c-49b6-a709-dcd971546b94" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_eba2001e-7d66-49fa-8a13-3d8360ad61e0" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_a163db99-2d1c-49b6-a709-dcd971546b94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheThreeMember_2da47523-8ed4-4141-b2fd-692f00246509" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_eba2001e-7d66-49fa-8a13-3d8360ad61e0" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheThreeMember_2da47523-8ed4-4141-b2fd-692f00246509" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_9efddedf-d394-402e-ad1a-eed052326896" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_StockholdersEquityNoteTable_add8f061-fb33-4a81-921d-ad961c1aa464" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_9efddedf-d394-402e-ad1a-eed052326896" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_9efddedf-d394-402e-ad1a-eed052326896_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_9efddedf-d394-402e-ad1a-eed052326896" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_9efddedf-d394-402e-ad1a-eed052326896_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_ccee47b6-39f7-4b9c-a056-71f8a7434d81" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_9efddedf-d394-402e-ad1a-eed052326896" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_ccee47b6-39f7-4b9c-a056-71f8a7434d81" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_5fb1a95d-e25f-4c3b-84dc-00f19efa5cff" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_ccee47b6-39f7-4b9c-a056-71f8a7434d81" xlink:to="loc_us-gaap_SubsequentEventMember_5fb1a95d-e25f-4c3b-84dc-00f19efa5cff" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/AccumulatedothercomprehensiveincomelossScheduleofAccumulatedOtherComprehensiveIncomelossDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#AccumulatedothercomprehensiveincomelossScheduleofAccumulatedOtherComprehensiveIncomelossDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/AccumulatedothercomprehensiveincomelossScheduleofAccumulatedOtherComprehensiveIncomelossDetail" xlink:type="extended" id="i75b57627f17546d8ae62178352f81fd4_AccumulatedothercomprehensiveincomelossScheduleofAccumulatedOtherComprehensiveIncomelossDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_364f9690-6371-467d-80e0-bf25844c671d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_37019074-ad08-4a79-ae2a-cdc9d42e1d0e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_364f9690-6371-467d-80e0-bf25844c671d" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_37019074-ad08-4a79-ae2a-cdc9d42e1d0e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_d2c0a68f-c098-4b8d-9d03-05f79ca09d7a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_37019074-ad08-4a79-ae2a-cdc9d42e1d0e" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_d2c0a68f-c098-4b8d-9d03-05f79ca09d7a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_8ccd8166-717b-4d30-859c-32377b85e96a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_37019074-ad08-4a79-ae2a-cdc9d42e1d0e" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_8ccd8166-717b-4d30-859c-32377b85e96a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_335284d5-9c74-4237-b2f4-ad91817ed678" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_37019074-ad08-4a79-ae2a-cdc9d42e1d0e" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_335284d5-9c74-4237-b2f4-ad91817ed678" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_8b406d5a-fc43-46e6-a381-33b92a5d689a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_37019074-ad08-4a79-ae2a-cdc9d42e1d0e" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_8b406d5a-fc43-46e6-a381-33b92a5d689a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest_e24882ed-f86c-4720-9cb2-dd19f9bf7bcb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_37019074-ad08-4a79-ae2a-cdc9d42e1d0e" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToNoncontrollingInterest_e24882ed-f86c-4720-9cb2-dd19f9bf7bcb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_831f85f9-d600-4acc-89e1-2af406195f2b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_37019074-ad08-4a79-ae2a-cdc9d42e1d0e" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_831f85f9-d600-4acc-89e1-2af406195f2b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_5d183769-85c3-4448-a6bb-d8aa8830e923" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_5f007b89-bdf7-4dd9-97fb-4fe0767db269" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_364f9690-6371-467d-80e0-bf25844c671d" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_5f007b89-bdf7-4dd9-97fb-4fe0767db269" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_521efc2b-4443-40ed-a7b6-50cdd68489cd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_5f007b89-bdf7-4dd9-97fb-4fe0767db269" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_521efc2b-4443-40ed-a7b6-50cdd68489cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_521efc2b-4443-40ed-a7b6-50cdd68489cd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_521efc2b-4443-40ed-a7b6-50cdd68489cd" xlink:to="loc_us-gaap_EquityComponentDomain_521efc2b-4443-40ed-a7b6-50cdd68489cd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_0bc5beb1-1e8e-43cc-b66c-dc00a2775ebc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_521efc2b-4443-40ed-a7b6-50cdd68489cd" xlink:to="loc_us-gaap_EquityComponentDomain_0bc5beb1-1e8e-43cc-b66c-dc00a2775ebc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember_f65db8a4-7083-4826-8acb-ffaecc6e4e18" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0bc5beb1-1e8e-43cc-b66c-dc00a2775ebc" xlink:to="loc_us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember_f65db8a4-7083-4826-8acb-ffaecc6e4e18" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterestMember_511b3b8d-a2d1-45de-88c3-f7800612d383" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0bc5beb1-1e8e-43cc-b66c-dc00a2775ebc" xlink:to="loc_us-gaap_AccumulatedGainLossCashFlowHedgeIncludingNoncontrollingInterestMember_511b3b8d-a2d1-45de-88c3-f7800612d383" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember_96163a06-f3e3-4b34-85a5-c6d4649df8a7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0bc5beb1-1e8e-43cc-b66c-dc00a2775ebc" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember_96163a06-f3e3-4b34-85a5-c6d4649df8a7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AociIncludingPortionAttributableToNoncontrollingInterestMember_047363b6-b169-4c2d-8817-230c88566f05" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AociIncludingPortionAttributableToNoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0bc5beb1-1e8e-43cc-b66c-dc00a2775ebc" xlink:to="loc_us-gaap_AociIncludingPortionAttributableToNoncontrollingInterestMember_047363b6-b169-4c2d-8817-230c88566f05" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/DividendsDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#DividendsDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/DividendsDetail" xlink:type="extended" id="i614c304f5fcd4450a405dc59b0005d26_DividendsDetail">
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DividendsLineItems_dec88f5b-5d48-4d61-8e82-179b38c38058" xlink:href="aqunf-20210630.xsd#aqunf_DividendsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStock_3d607284-6f9e-4b37-adbe-07cced9501ab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DividendsCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_DividendsLineItems_dec88f5b-5d48-4d61-8e82-179b38c38058" xlink:to="loc_us-gaap_DividendsCommonStock_3d607284-6f9e-4b37-adbe-07cced9501ab" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_910a99ba-2f3e-4649-8910-ccda5813565e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_DividendsLineItems_dec88f5b-5d48-4d61-8e82-179b38c38058" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_910a99ba-2f3e-4649-8910-ccda5813565e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPreferredStock_9c9f0c50-eda0-4b97-9773-e5a89fe141ad" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DividendsPreferredStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_DividendsLineItems_dec88f5b-5d48-4d61-8e82-179b38c38058" xlink:to="loc_us-gaap_DividendsPreferredStock_9c9f0c50-eda0-4b97-9773-e5a89fe141ad" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendsPerShareCashPaid_6428881a-cfb8-4019-af02-af6f9cffb463" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PreferredStockDividendsPerShareCashPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_DividendsLineItems_dec88f5b-5d48-4d61-8e82-179b38c38058" xlink:to="loc_us-gaap_PreferredStockDividendsPerShareCashPaid_6428881a-cfb8-4019-af02-af6f9cffb463" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DividendsTable_99db1a92-6a06-4106-a589-c537eb2cddc5" xlink:href="aqunf-20210630.xsd#aqunf_DividendsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_aqunf_DividendsLineItems_dec88f5b-5d48-4d61-8e82-179b38c38058" xlink:to="loc_aqunf_DividendsTable_99db1a92-6a06-4106-a589-c537eb2cddc5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_a06833db-9d7b-4fdf-b0f3-570a23f09337" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_DividendsTable_99db1a92-6a06-4106-a589-c537eb2cddc5" xlink:to="loc_us-gaap_StatementClassOfStockAxis_a06833db-9d7b-4fdf-b0f3-570a23f09337" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_a06833db-9d7b-4fdf-b0f3-570a23f09337_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_a06833db-9d7b-4fdf-b0f3-570a23f09337" xlink:to="loc_us-gaap_ClassOfStockDomain_a06833db-9d7b-4fdf-b0f3-570a23f09337_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_74db7f24-6630-4630-a719-71b314018351" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_a06833db-9d7b-4fdf-b0f3-570a23f09337" xlink:to="loc_us-gaap_ClassOfStockDomain_74db7f24-6630-4630-a719-71b314018351" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_e264a431-fd62-4137-961b-2ba671f264fc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_74db7f24-6630-4630-a719-71b314018351" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_e264a431-fd62-4137-961b-2ba671f264fc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesDPreferredStockMember_4ea0ba06-0dbd-4274-8558-3ee5eaa5af02" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SeriesDPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_74db7f24-6630-4630-a719-71b314018351" xlink:to="loc_us-gaap_SeriesDPreferredStockMember_4ea0ba06-0dbd-4274-8558-3ee5eaa5af02" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/RelatedpartytransactionsDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#RelatedpartytransactionsDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/RelatedpartytransactionsDetail" xlink:type="extended" id="i9d2058e98c094632980b5ad61925d94a_RelatedpartytransactionsDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_36132491-c409-4627-a8bd-d64dfcce4c13" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ReimbursementofExpensesReceivedbyRelatedParties_56b6cb0f-48a7-4f50-8389-58646f7ba8b3" xlink:href="aqunf-20210630.xsd#aqunf_ReimbursementofExpensesReceivedbyRelatedParties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_36132491-c409-4627-a8bd-d64dfcce4c13" xlink:to="loc_aqunf_ReimbursementofExpensesReceivedbyRelatedParties_56b6cb0f-48a7-4f50-8389-58646f7ba8b3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty_9088cccd-83f7-48ea-910c-d240a635df2c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_36132491-c409-4627-a8bd-d64dfcce4c13" xlink:to="loc_us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty_9088cccd-83f7-48ea-910c-d240a635df2c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentOfNotesReceivableFromRelatedParties_165e1b79-6bda-4269-a1bd-fd95c5cf834b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RepaymentOfNotesReceivableFromRelatedParties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_36132491-c409-4627-a8bd-d64dfcce4c13" xlink:to="loc_us-gaap_RepaymentOfNotesReceivableFromRelatedParties_165e1b79-6bda-4269-a1bd-fd95c5cf834b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_PeriodForOptionToPurchaseInterestInJointVenture_e4c248f7-89c6-4d8a-9264-bf543b332192" xlink:href="aqunf-20210630.xsd#aqunf_PeriodForOptionToPurchaseInterestInJointVenture"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_36132491-c409-4627-a8bd-d64dfcce4c13" xlink:to="loc_aqunf_PeriodForOptionToPurchaseInterestInJointVenture_e4c248f7-89c6-4d8a-9264-bf543b332192" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_OptionToPurchaseInterestInJointVenture_91e80f13-080b-417e-8fa8-157bac32eabf" xlink:href="aqunf-20210630.xsd#aqunf_OptionToPurchaseInterestInJointVenture"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_36132491-c409-4627-a8bd-d64dfcce4c13" xlink:to="loc_aqunf_OptionToPurchaseInterestInJointVenture_91e80f13-080b-417e-8fa8-157bac32eabf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_1ffa37c9-6841-4228-a750-8037b37d4c85" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_36132491-c409-4627-a8bd-d64dfcce4c13" xlink:to="loc_us-gaap_DebtInstrumentTerm_1ffa37c9-6841-4228-a750-8037b37d4c85" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_9d42fe1c-b0cc-444e-8352-c3027f0b6c4f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_36132491-c409-4627-a8bd-d64dfcce4c13" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_9d42fe1c-b0cc-444e-8352-c3027f0b6c4f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest_135febba-cbc8-4026-a656-692bae9ca759" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_36132491-c409-4627-a8bd-d64dfcce4c13" xlink:to="loc_us-gaap_NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest_135febba-cbc8-4026-a656-692bae9ca759" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CollateralShortfallTriggerAsPercentOfMarketValueOfShares_3814a989-090d-40fc-a95b-f2eae56b4e81" xlink:href="aqunf-20210630.xsd#aqunf_CollateralShortfallTriggerAsPercentOfMarketValueOfShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_36132491-c409-4627-a8bd-d64dfcce4c13" xlink:to="loc_aqunf_CollateralShortfallTriggerAsPercentOfMarketValueOfShares_3814a989-090d-40fc-a95b-f2eae56b4e81" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToRedeemableNoncontrollingInterest_cf3b6a6d-5ecd-4943-808e-9b8d477579d0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLossAttributableToRedeemableNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_36132491-c409-4627-a8bd-d64dfcce4c13" xlink:to="loc_us-gaap_NetIncomeLossAttributableToRedeemableNoncontrollingInterest_cf3b6a6d-5ecd-4943-808e-9b8d477579d0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_RedeemableNoncontrollingInterestDecreasefromDistributionstoNoncontrollingInterestHolders_1d2ed9b8-42d8-45a4-98e3-68ced14d832e" xlink:href="aqunf-20210630.xsd#aqunf_RedeemableNoncontrollingInterestDecreasefromDistributionstoNoncontrollingInterestHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_36132491-c409-4627-a8bd-d64dfcce4c13" xlink:to="loc_aqunf_RedeemableNoncontrollingInterestDecreasefromDistributionstoNoncontrollingInterestHolders_1d2ed9b8-42d8-45a4-98e3-68ced14d832e" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterest_8a313b02-d444-4920-a5aa-9470ccd3790c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MinorityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_36132491-c409-4627-a8bd-d64dfcce4c13" xlink:to="loc_us-gaap_MinorityInterest_8a313b02-d444-4920-a5aa-9470ccd3790c" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_b5834fbf-e02b-46b2-b238-951b61517eea" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_36132491-c409-4627-a8bd-d64dfcce4c13" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_b5834fbf-e02b-46b2-b238-951b61517eea" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_145dc537-f0b8-4a81-bd16-0efa83054c64" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_36132491-c409-4627-a8bd-d64dfcce4c13" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_145dc537-f0b8-4a81-bd16-0efa83054c64" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_b52f22c1-2d00-49cf-93fd-dae6ade203a4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_145dc537-f0b8-4a81-bd16-0efa83054c64" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_b52f22c1-2d00-49cf-93fd-dae6ade203a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_b52f22c1-2d00-49cf-93fd-dae6ade203a4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_b52f22c1-2d00-49cf-93fd-dae6ade203a4" xlink:to="loc_us-gaap_RelatedPartyDomain_b52f22c1-2d00-49cf-93fd-dae6ade203a4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_3ccb9822-7a87-42c9-901c-f20914215ce2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_b52f22c1-2d00-49cf-93fd-dae6ade203a4" xlink:to="loc_us-gaap_RelatedPartyDomain_3ccb9822-7a87-42c9-901c-f20914215ce2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvesteeMember_512cc16e-c7b0-4d3c-9a53-bcafc3ddf7fd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityMethodInvesteeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_3ccb9822-7a87-42c9-901c-f20914215ce2" xlink:to="loc_us-gaap_EquityMethodInvesteeMember_512cc16e-c7b0-4d3c-9a53-bcafc3ddf7fd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AltavistaMember_259e5f7a-5b26-4095-bc17-33391a40306c" xlink:href="aqunf-20210630.xsd#aqunf_AltavistaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_3ccb9822-7a87-42c9-901c-f20914215ce2" xlink:to="loc_aqunf_AltavistaMember_259e5f7a-5b26-4095-bc17-33391a40306c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AffiliatedEntityMember_69147a5e-3579-4fb8-8a0a-13d1beb058af" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_AffiliatedEntityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_3ccb9822-7a87-42c9-901c-f20914215ce2" xlink:to="loc_srt_AffiliatedEntityMember_69147a5e-3579-4fb8-8a0a-13d1beb058af" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AbengoaInvestmentsMember_26f94249-8c77-4b9d-aa20-9053a5df33c5" xlink:href="aqunf-20210630.xsd#aqunf_AbengoaInvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_3ccb9822-7a87-42c9-901c-f20914215ce2" xlink:to="loc_aqunf_AbengoaInvestmentsMember_26f94249-8c77-4b9d-aa20-9053a5df33c5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionAxis_26ba3aa9-0bc6-4207-9c4b-ffe2d1e2b5a3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_145dc537-f0b8-4a81-bd16-0efa83054c64" xlink:to="loc_us-gaap_RelatedPartyTransactionAxis_26ba3aa9-0bc6-4207-9c4b-ffe2d1e2b5a3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_26ba3aa9-0bc6-4207-9c4b-ffe2d1e2b5a3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_26ba3aa9-0bc6-4207-9c4b-ffe2d1e2b5a3" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_26ba3aa9-0bc6-4207-9c4b-ffe2d1e2b5a3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_277232e6-aff9-4bcb-b1fb-7c8fe9812677" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_26ba3aa9-0bc6-4207-9c4b-ffe2d1e2b5a3" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_277232e6-aff9-4bcb-b1fb-7c8fe9812677" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvesteeMember_55e7fd2b-d1c5-4c45-bcee-4993a76dcdee" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityMethodInvesteeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_277232e6-aff9-4bcb-b1fb-7c8fe9812677" xlink:to="loc_us-gaap_EquityMethodInvesteeMember_55e7fd2b-d1c5-4c45-bcee-4993a76dcdee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_RedeemableNonControllingInterestMember_5327a89e-2b39-4541-a8c3-58111b74173a" xlink:href="aqunf-20210630.xsd#aqunf_RedeemableNonControllingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_277232e6-aff9-4bcb-b1fb-7c8fe9812677" xlink:to="loc_aqunf_RedeemableNonControllingInterestMember_5327a89e-2b39-4541-a8c3-58111b74173a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_RelatedPartiesMember_7ee61c69-d2bd-46ba-a0b2-a5ce742b5a0a" xlink:href="aqunf-20210630.xsd#aqunf_RelatedPartiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_277232e6-aff9-4bcb-b1fb-7c8fe9812677" xlink:to="loc_aqunf_RelatedPartiesMember_7ee61c69-d2bd-46ba-a0b2-a5ce742b5a0a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_9a2ad083-fd6a-4e67-838c-5c1db4caca07" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_145dc537-f0b8-4a81-bd16-0efa83054c64" xlink:to="loc_us-gaap_CreditFacilityAxis_9a2ad083-fd6a-4e67-838c-5c1db4caca07" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_9a2ad083-fd6a-4e67-838c-5c1db4caca07_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_9a2ad083-fd6a-4e67-838c-5c1db4caca07" xlink:to="loc_us-gaap_CreditFacilityDomain_9a2ad083-fd6a-4e67-838c-5c1db4caca07_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_6d276d19-467f-4a26-bd68-20db1ca99fef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_9a2ad083-fd6a-4e67-838c-5c1db4caca07" xlink:to="loc_us-gaap_CreditFacilityDomain_6d276d19-467f-4a26-bd68-20db1ca99fef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_e687a8e5-2da1-4016-aea1-d240a32a2c1b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_6d276d19-467f-4a26-bd68-20db1ca99fef" xlink:to="loc_us-gaap_SecuredDebtMember_e687a8e5-2da1-4016-aea1-d240a32a2c1b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_aa4267e2-b5e6-4ba1-b94c-06425e8d3be5" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_145dc537-f0b8-4a81-bd16-0efa83054c64" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_aa4267e2-b5e6-4ba1-b94c-06425e8d3be5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_aa4267e2-b5e6-4ba1-b94c-06425e8d3be5_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_aa4267e2-b5e6-4ba1-b94c-06425e8d3be5" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_aa4267e2-b5e6-4ba1-b94c-06425e8d3be5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_00e8bd8e-2c65-4aa7-ae57-64359943e845" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_aa4267e2-b5e6-4ba1-b94c-06425e8d3be5" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_00e8bd8e-2c65-4aa7-ae57-64359943e845" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AYESCanadaMember_cb5530ba-5947-422d-a7bd-d6660ad448b7" xlink:href="aqunf-20210630.xsd#aqunf_AYESCanadaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_00e8bd8e-2c65-4aa7-ae57-64359943e845" xlink:to="loc_aqunf_AYESCanadaMember_cb5530ba-5947-422d-a7bd-d6660ad448b7" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/NoncontrollingInterestsandRedeemablenoncontrollingInterestNetLossAttributabletoNonControllingInterestDetails" xlink:type="simple" xlink:href="aqunf-20210630.xsd#NoncontrollingInterestsandRedeemablenoncontrollingInterestNetLossAttributabletoNonControllingInterestDetails"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/NoncontrollingInterestsandRedeemablenoncontrollingInterestNetLossAttributabletoNonControllingInterestDetails" xlink:type="extended" id="id26575dfbed94ee3bc85e385c6cb709f_NoncontrollingInterestsandRedeemablenoncontrollingInterestNetLossAttributabletoNonControllingInterestDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestLineItems_ea167e14-7644-4e02-8bd0-9e216ff23591" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MinorityInterestLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_fa845fa6-9224-4a84-afbb-bc166fc91668" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_ea167e14-7644-4e02-8bd0-9e216ff23591" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_fa845fa6-9224-4a84-afbb-bc166fc91668" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToRedeemableNoncontrollingInterest_9e51afbf-b40f-48f3-a7d6-f7e70d881d0b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLossAttributableToRedeemableNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_ea167e14-7644-4e02-8bd0-9e216ff23591" xlink:to="loc_us-gaap_NetIncomeLossAttributableToRedeemableNoncontrollingInterest_9e51afbf-b40f-48f3-a7d6-f7e70d881d0b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NetIncomeLossAttributabletoRedeemableNoncontrollingInterestHeldByRelatedParty_c8a2e9d2-5d47-4fc7-b095-3c036c101eca" xlink:href="aqunf-20210630.xsd#aqunf_NetIncomeLossAttributabletoRedeemableNoncontrollingInterestHeldByRelatedParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_ea167e14-7644-4e02-8bd0-9e216ff23591" xlink:to="loc_aqunf_NetIncomeLossAttributabletoRedeemableNoncontrollingInterestHeldByRelatedParty_c8a2e9d2-5d47-4fc7-b095-3c036c101eca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NetIncomeLossAttributableToNoncontrollingInterestNetOfRelatedParty_24340fed-1736-42f4-8880-63c4e2ca9475" xlink:href="aqunf-20210630.xsd#aqunf_NetIncomeLossAttributableToNoncontrollingInterestNetOfRelatedParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_ea167e14-7644-4e02-8bd0-9e216ff23591" xlink:to="loc_aqunf_NetIncomeLossAttributableToNoncontrollingInterestNetOfRelatedParty_24340fed-1736-42f4-8880-63c4e2ca9475" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NumberOfWindFarms_1a85c6b9-4e28-4edd-a565-efa181d5b2f5" xlink:href="aqunf-20210630.xsd#aqunf_NumberOfWindFarms"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_ea167e14-7644-4e02-8bd0-9e216ff23591" xlink:to="loc_aqunf_NumberOfWindFarms_1a85c6b9-4e28-4edd-a565-efa181d5b2f5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest_30bbea7c-7237-4ae8-98ca-37796e833936" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MinorityInterestLineItems_ea167e14-7644-4e02-8bd0-9e216ff23591" xlink:to="loc_us-gaap_NoncontrollingInterestIncreaseFromSaleOfParentEquityInterest_30bbea7c-7237-4ae8-98ca-37796e833936" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestTable_355b9445-c745-4ad0-9b5d-9f8e0dc43cdc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MinorityInterestTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_MinorityInterestLineItems_ea167e14-7644-4e02-8bd0-9e216ff23591" xlink:to="loc_us-gaap_MinorityInterestTable_355b9445-c745-4ad0-9b5d-9f8e0dc43cdc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_410e0181-d643-4048-9aa4-611b050204ff" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_355b9445-c745-4ad0-9b5d-9f8e0dc43cdc" xlink:to="loc_us-gaap_StatementClassOfStockAxis_410e0181-d643-4048-9aa4-611b050204ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_410e0181-d643-4048-9aa4-611b050204ff_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_410e0181-d643-4048-9aa4-611b050204ff" xlink:to="loc_us-gaap_ClassOfStockDomain_410e0181-d643-4048-9aa4-611b050204ff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_0f6ef783-3a18-49b2-958b-49acd4c6ec9c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_410e0181-d643-4048-9aa4-611b050204ff" xlink:to="loc_us-gaap_ClassOfStockDomain_0f6ef783-3a18-49b2-958b-49acd4c6ec9c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAMember_8c140f7d-3ed8-45bd-99df-df4fc2693da6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SeriesAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_0f6ef783-3a18-49b2-958b-49acd4c6ec9c" xlink:to="loc_us-gaap_SeriesAMember_8c140f7d-3ed8-45bd-99df-df4fc2693da6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_a08e992b-f30f-47f9-bb11-2d9176cc1ed8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_355b9445-c745-4ad0-9b5d-9f8e0dc43cdc" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_a08e992b-f30f-47f9-bb11-2d9176cc1ed8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_a08e992b-f30f-47f9-bb11-2d9176cc1ed8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_a08e992b-f30f-47f9-bb11-2d9176cc1ed8" xlink:to="loc_us-gaap_EquityComponentDomain_a08e992b-f30f-47f9-bb11-2d9176cc1ed8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_d6a747d6-3f88-4043-a506-46bc97c2a609" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_a08e992b-f30f-47f9-bb11-2d9176cc1ed8" xlink:to="loc_us-gaap_EquityComponentDomain_d6a747d6-3f88-4043-a506-46bc97c2a609" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ClassAPartnershipUnitsMember_4d4f904a-3597-400c-b9d1-bb908db727bc" xlink:href="aqunf-20210630.xsd#aqunf_ClassAPartnershipUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_d6a747d6-3f88-4043-a506-46bc97c2a609" xlink:to="loc_aqunf_ClassAPartnershipUnitsMember_4d4f904a-3597-400c-b9d1-bb908db727bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_OtherNoncontrollingInterestMember_ea43aebb-8a7f-4b76-86fd-42cdfa4c154e" xlink:href="aqunf-20210630.xsd#aqunf_OtherNoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_d6a747d6-3f88-4043-a506-46bc97c2a609" xlink:to="loc_aqunf_OtherNoncontrollingInterestMember_ea43aebb-8a7f-4b76-86fd-42cdfa4c154e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_5f3474ad-5122-4bab-96ad-a534d16b4878" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_355b9445-c745-4ad0-9b5d-9f8e0dc43cdc" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_5f3474ad-5122-4bab-96ad-a534d16b4878" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5f3474ad-5122-4bab-96ad-a534d16b4878_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_5f3474ad-5122-4bab-96ad-a534d16b4878" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5f3474ad-5122-4bab-96ad-a534d16b4878_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a9f7e1f0-9f1c-4fc7-87bb-c20a481dad19" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_5f3474ad-5122-4bab-96ad-a534d16b4878" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a9f7e1f0-9f1c-4fc7-87bb-c20a481dad19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NorthForkRidgeWindProjectMember_78e9d92b-b374-4696-a585-7156c096abe0" xlink:href="aqunf-20210630.xsd#aqunf_NorthForkRidgeWindProjectMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a9f7e1f0-9f1c-4fc7-87bb-c20a481dad19" xlink:to="loc_aqunf_NorthForkRidgeWindProjectMember_78e9d92b-b374-4696-a585-7156c096abe0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_MidWestWindDevelopmentProjectMember_671ccf8e-6a76-4308-bccb-514be5bc38d0" xlink:href="aqunf-20210630.xsd#aqunf_MidWestWindDevelopmentProjectMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a9f7e1f0-9f1c-4fc7-87bb-c20a481dad19" xlink:to="loc_aqunf_MidWestWindDevelopmentProjectMember_671ccf8e-6a76-4308-bccb-514be5bc38d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SugarCreekWindFacilityMember_bd92be3b-f025-4c14-86e9-9a0860ccc2ad" xlink:href="aqunf-20210630.xsd#aqunf_SugarCreekWindFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a9f7e1f0-9f1c-4fc7-87bb-c20a481dad19" xlink:to="loc_aqunf_SugarCreekWindFacilityMember_bd92be3b-f025-4c14-86e9-9a0860ccc2ad" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_MaverickCreekWindFacilityMember_5bfb5c28-e8ff-44d2-9c0a-280f126d6d4f" xlink:href="aqunf-20210630.xsd#aqunf_MaverickCreekWindFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a9f7e1f0-9f1c-4fc7-87bb-c20a481dad19" xlink:to="loc_aqunf_MaverickCreekWindFacilityMember_5bfb5c28-e8ff-44d2-9c0a-280f126d6d4f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_0b26685e-f4d1-4d0a-9ba4-4aada73272aa" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_MinorityInterestTable_355b9445-c745-4ad0-9b5d-9f8e0dc43cdc" xlink:to="loc_srt_OwnershipAxis_0b26685e-f4d1-4d0a-9ba4-4aada73272aa" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_0b26685e-f4d1-4d0a-9ba4-4aada73272aa_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_0b26685e-f4d1-4d0a-9ba4-4aada73272aa" xlink:to="loc_srt_OwnershipDomain_0b26685e-f4d1-4d0a-9ba4-4aada73272aa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_f855ff72-953f-4b0f-bde5-6fde4b3460ff" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_0b26685e-f4d1-4d0a-9ba4-4aada73272aa" xlink:to="loc_srt_OwnershipDomain_f855ff72-953f-4b0f-bde5-6fde4b3460ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ThirdPartyMember_a0da0874-430f-48e9-8ba3-80e3d3c70f5a" xlink:href="aqunf-20210630.xsd#aqunf_ThirdPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_f855ff72-953f-4b0f-bde5-6fde4b3460ff" xlink:to="loc_aqunf_ThirdPartyMember_a0da0874-430f-48e9-8ba3-80e3d3c70f5a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/BasicanddilutednetearningspershareScheduleofEarningsperShareDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#BasicanddilutednetearningspershareScheduleofEarningsperShareDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/BasicanddilutednetearningspershareScheduleofEarningsperShareDetail" xlink:type="extended" id="i383c2c822f2f4e6bae7b903690a1568b_BasicanddilutednetearningspershareScheduleofEarningsperShareDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_ee6eb1dc-cb0b-4a99-9955-c823dafcfd75" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_09a5385a-ddc4-4b31-84be-e9293d6db04d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_ee6eb1dc-cb0b-4a99-9955-c823dafcfd75" xlink:to="loc_us-gaap_NetIncomeLoss_09a5385a-ddc4-4b31-84be-e9293d6db04d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockDividendsIncomeStatementImpact_e0fbd3dc-5a39-424b-ac5a-76aacfd648a6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PreferredStockDividendsIncomeStatementImpact"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_ee6eb1dc-cb0b-4a99-9955-c823dafcfd75" xlink:to="loc_us-gaap_PreferredStockDividendsIncomeStatementImpact_e0fbd3dc-5a39-424b-ac5a-76aacfd648a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NetIncomeLossfromContinuingOperationsAttributableToCommonStockHoldersBasicAndDiluted_cea4eb53-98dc-46bf-ac47-de1e36cfbcd7" xlink:href="aqunf-20210630.xsd#aqunf_NetIncomeLossfromContinuingOperationsAttributableToCommonStockHoldersBasicAndDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_ee6eb1dc-cb0b-4a99-9955-c823dafcfd75" xlink:to="loc_aqunf_NetIncomeLossfromContinuingOperationsAttributableToCommonStockHoldersBasicAndDiluted_cea4eb53-98dc-46bf-ac47-de1e36cfbcd7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_WeightedAverageNumberOfSharesAbstract_c871a813-5de9-45ab-b81e-f0a097b59aae" xlink:href="aqunf-20210630.xsd#aqunf_WeightedAverageNumberOfSharesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_ee6eb1dc-cb0b-4a99-9955-c823dafcfd75" xlink:to="loc_aqunf_WeightedAverageNumberOfSharesAbstract_c871a813-5de9-45ab-b81e-f0a097b59aae" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_9ab8d496-66fa-4801-8e3f-949433da434b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_WeightedAverageNumberOfSharesAbstract_c871a813-5de9-45ab-b81e-f0a097b59aae" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_9ab8d496-66fa-4801-8e3f-949433da434b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_WeightedAveragePotentiallyDilutiveShareOptionsAndAwardsOutstanding_14c18b78-f13c-4d7c-b6bd-098ae87d6acf" xlink:href="aqunf-20210630.xsd#aqunf_WeightedAveragePotentiallyDilutiveShareOptionsAndAwardsOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_WeightedAverageNumberOfSharesAbstract_c871a813-5de9-45ab-b81e-f0a097b59aae" xlink:to="loc_aqunf_WeightedAveragePotentiallyDilutiveShareOptionsAndAwardsOutstanding_14c18b78-f13c-4d7c-b6bd-098ae87d6acf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_4df2d8a6-8fec-499e-ba6c-581faa463d14" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_WeightedAverageNumberOfSharesAbstract_c871a813-5de9-45ab-b81e-f0a097b59aae" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_4df2d8a6-8fec-499e-ba6c-581faa463d14" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_e755f6c0-20b3-403d-8461-5f9a824c2cf9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_ee6eb1dc-cb0b-4a99-9955-c823dafcfd75" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_e755f6c0-20b3-403d-8461-5f9a824c2cf9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_27bb13f7-c45a-4b01-aebb-deec6e6eab1f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_e755f6c0-20b3-403d-8461-5f9a824c2cf9" xlink:to="loc_us-gaap_StatementClassOfStockAxis_27bb13f7-c45a-4b01-aebb-deec6e6eab1f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_27bb13f7-c45a-4b01-aebb-deec6e6eab1f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_27bb13f7-c45a-4b01-aebb-deec6e6eab1f" xlink:to="loc_us-gaap_ClassOfStockDomain_27bb13f7-c45a-4b01-aebb-deec6e6eab1f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_7d389765-723f-4971-8845-ddd690a14f76" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_27bb13f7-c45a-4b01-aebb-deec6e6eab1f" xlink:to="loc_us-gaap_ClassOfStockDomain_7d389765-723f-4971-8845-ddd690a14f76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_6195a502-b80c-4c4e-ac05-27b5397a71b8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_7d389765-723f-4971-8845-ddd690a14f76" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_6195a502-b80c-4c4e-ac05-27b5397a71b8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesDPreferredStockMember_c3f4ae31-573d-4bb7-b8b7-d1af977a8708" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SeriesDPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_7d389765-723f-4971-8845-ddd690a14f76" xlink:to="loc_us-gaap_SeriesDPreferredStockMember_c3f4ae31-573d-4bb7-b8b7-d1af977a8708" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/BasicanddilutednetearningspershareAdditionalInformationDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#BasicanddilutednetearningspershareAdditionalInformationDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/BasicanddilutednetearningspershareAdditionalInformationDetail" xlink:type="extended" id="ia0ea62cbab6746309a0f453e556a62d2_BasicanddilutednetearningspershareAdditionalInformationDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_6ac8b370-4177-45f7-85d8-f8a5cc6fd9ab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_ca98076e-fe77-4d54-82e2-0b0578a850e9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_6ac8b370-4177-45f7-85d8-f8a5cc6fd9ab" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_ca98076e-fe77-4d54-82e2-0b0578a850e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_e238e6c1-c8fc-4cad-90f7-94bd19f10e10" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_6ac8b370-4177-45f7-85d8-f8a5cc6fd9ab" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_e238e6c1-c8fc-4cad-90f7-94bd19f10e10" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_548d8181-f7b5-40ca-94ed-33c41c514e1a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_e238e6c1-c8fc-4cad-90f7-94bd19f10e10" xlink:to="loc_us-gaap_DebtInstrumentAxis_548d8181-f7b5-40ca-94ed-33c41c514e1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_548d8181-f7b5-40ca-94ed-33c41c514e1a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_548d8181-f7b5-40ca-94ed-33c41c514e1a" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_548d8181-f7b5-40ca-94ed-33c41c514e1a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_cc0d5266-29e1-4407-80dd-a0de6fe1f2ae" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_548d8181-f7b5-40ca-94ed-33c41c514e1a" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_cc0d5266-29e1-4407-80dd-a0de6fe1f2ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_OptionsandConvertibleDebenturesMember_74289acc-17a4-4742-91bd-267209952241" xlink:href="aqunf-20210630.xsd#aqunf_OptionsandConvertibleDebenturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_cc0d5266-29e1-4407-80dd-a0de6fe1f2ae" xlink:to="loc_aqunf_OptionsandConvertibleDebenturesMember_74289acc-17a4-4742-91bd-267209952241" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/SegmentedinformationResultsofOperationsandAssetsforSegmentsDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#SegmentedinformationResultsofOperationsandAssetsforSegmentsDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/SegmentedinformationResultsofOperationsandAssetsforSegmentsDetail" xlink:type="extended" id="i20f8c78186714ee1a87d8a5fbbb39317_SegmentedinformationResultsofOperationsandAssetsforSegmentsDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_5db76688-9502-4be8-b857-cecd0e55ea97" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_us-gaap_RevenuesAbstract_5db76688-9502-4be8-b857-cecd0e55ea97" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_d391d50c-9549-4f16-bf9b-734aee6d8333" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_5db76688-9502-4be8-b857-cecd0e55ea97" xlink:to="loc_us-gaap_Revenues_d391d50c-9549-4f16-bf9b-734aee6d8333" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CostofFuelandPowerPurchased_a6911839-f0bd-4427-a77c-8bee89b62e94" xlink:href="aqunf-20210630.xsd#aqunf_CostofFuelandPowerPurchased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_5db76688-9502-4be8-b857-cecd0e55ea97" xlink:to="loc_aqunf_CostofFuelandPowerPurchased_a6911839-f0bd-4427-a77c-8bee89b62e94" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_RevenueNetofRegulatedFuelandPowerPurchased_6333204d-6b44-4d82-860c-53eaf2ec00ec" xlink:href="aqunf-20210630.xsd#aqunf_RevenueNetofRegulatedFuelandPowerPurchased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_5db76688-9502-4be8-b857-cecd0e55ea97" xlink:to="loc_aqunf_RevenueNetofRegulatedFuelandPowerPurchased_6333204d-6b44-4d82-860c-53eaf2ec00ec" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingCostsAndExpenses_8c647daa-d031-4256-8936-2f54d8b19a9f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingCostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_us-gaap_OperatingCostsAndExpenses_8c647daa-d031-4256-8936-2f54d8b19a9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_406e1318-f448-4ddb-990e-2f1df420d75a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_406e1318-f448-4ddb-990e-2f1df420d75a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_f530b6f3-d154-4791-a711-eb9ae0acc94e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_f530b6f3-d154-4791-a711-eb9ae0acc94e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_a942b741-9c56-4962-8562-73afbef48072" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_a942b741-9c56-4962-8562-73afbef48072" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_a62027dc-83b2-4cf9-8aa5-73833b382827" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_us-gaap_OperatingIncomeLoss_a62027dc-83b2-4cf9-8aa5-73833b382827" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_e6f48980-1112-4f9a-8ee1-88df838c2958" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_us-gaap_InterestExpense_e6f48980-1112-4f9a-8ee1-88df838c2958" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnInvestments_247ae2ef-d5d6-4dae-85f9-db809443e603" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainLossOnInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_us-gaap_GainLossOnInvestments_247ae2ef-d5d6-4dae-85f9-db809443e603" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingGainsLosses_e77021b6-7658-4977-8bbf-1c5463287dbc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherNonoperatingGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_us-gaap_OtherNonoperatingGainsLosses_e77021b6-7658-4977-8bbf-1c5463287dbc" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_ba1e4883-474f-4d1d-8593-a2f0685d0bf7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_ba1e4883-474f-4d1d-8593-a2f0685d0bf7" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_1fd3bb13-b64d-4922-8890-456ea347e0fa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_1fd3bb13-b64d-4922-8890-456ea347e0fa" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentsFairValueDisclosure_b241138f-7187-49bf-b4fa-7e3861f82887" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityMethodInvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_us-gaap_EquityMethodInvestmentsFairValueDisclosure_b241138f-7187-49bf-b4fa-7e3861f82887" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments_6ebe1e90-99ed-48ee-9fee-917bd4ffb347" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_us-gaap_EquityMethodInvestments_6ebe1e90-99ed-48ee-9fee-917bd4ffb347" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_70ad187f-9773-47c2-a606-d1e8d3c8d01f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_us-gaap_Assets_70ad187f-9773-47c2-a606-d1e8d3c8d01f" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireProductiveAssets_77a69111-5bc2-4306-a313-6962ace7292a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToAcquireProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_us-gaap_PaymentsToAcquireProductiveAssets_77a69111-5bc2-4306-a313-6962ace7292a" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_RevenueNotfromContractwithCustomerHedgingGains_07c0e252-5797-4017-a2f8-f9d7448406c4" xlink:href="aqunf-20210630.xsd#aqunf_RevenueNotfromContractwithCustomerHedgingGains"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_aqunf_RevenueNotfromContractwithCustomerHedgingGains_07c0e252-5797-4017-a2f8-f9d7448406c4" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_RevenueNotFromContractwithCustomerAlternativeRevenueProgram_6c472eac-7987-4331-b8e2-62b4c4fa6cd5" xlink:href="aqunf-20210630.xsd#aqunf_RevenueNotFromContractwithCustomerAlternativeRevenueProgram"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_aqunf_RevenueNotFromContractwithCustomerAlternativeRevenueProgram_6c472eac-7987-4331-b8e2-62b4c4fa6cd5" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_6937708e-8eca-47a9-9641-973bd8ae72f3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_e3a85b0f-e3fc-45ea-ad74-f6521f54817b" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_6937708e-8eca-47a9-9641-973bd8ae72f3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_f13c3ba0-23dd-4f49-b6e8-d1fd1fe4d254" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_6937708e-8eca-47a9-9641-973bd8ae72f3" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_f13c3ba0-23dd-4f49-b6e8-d1fd1fe4d254" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_f13c3ba0-23dd-4f49-b6e8-d1fd1fe4d254_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_f13c3ba0-23dd-4f49-b6e8-d1fd1fe4d254" xlink:to="loc_us-gaap_SegmentDomain_f13c3ba0-23dd-4f49-b6e8-d1fd1fe4d254_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_4c029685-c903-4973-af6a-477d4b007b09" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_f13c3ba0-23dd-4f49-b6e8-d1fd1fe4d254" xlink:to="loc_us-gaap_SegmentDomain_4c029685-c903-4973-af6a-477d4b007b09" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_RegulatedServicesGroupMember_cd791d03-0670-468d-b428-1841439ad784" xlink:href="aqunf-20210630.xsd#aqunf_RegulatedServicesGroupMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_4c029685-c903-4973-af6a-477d4b007b09" xlink:to="loc_aqunf_RegulatedServicesGroupMember_cd791d03-0670-468d-b428-1841439ad784" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_RenewableEnergyGroupMember_435297a0-72a5-47e1-a50b-6d1f0bfc174c" xlink:href="aqunf-20210630.xsd#aqunf_RenewableEnergyGroupMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_4c029685-c903-4973-af6a-477d4b007b09" xlink:to="loc_aqunf_RenewableEnergyGroupMember_435297a0-72a5-47e1-a50b-6d1f0bfc174c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateAndOtherMember_ad5b5b82-1294-4827-9d97-e4624971c7d9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CorporateAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_4c029685-c903-4973-af6a-477d4b007b09" xlink:to="loc_us-gaap_CorporateAndOtherMember_ad5b5b82-1294-4827-9d97-e4624971c7d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_ce87b763-da90-4c24-b7db-754cddae5bb9" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_6937708e-8eca-47a9-9641-973bd8ae72f3" xlink:to="loc_srt_ConsolidationItemsAxis_ce87b763-da90-4c24-b7db-754cddae5bb9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_ce87b763-da90-4c24-b7db-754cddae5bb9_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_ce87b763-da90-4c24-b7db-754cddae5bb9" xlink:to="loc_srt_ConsolidationItemsDomain_ce87b763-da90-4c24-b7db-754cddae5bb9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_a4742a72-3ce4-4fec-adf4-08935c975ed3" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_ce87b763-da90-4c24-b7db-754cddae5bb9" xlink:to="loc_srt_ConsolidationItemsDomain_a4742a72-3ce4-4fec-adf4-08935c975ed3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_2f9a3a3d-577d-4c07-99b1-a9e623c73d07" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_a4742a72-3ce4-4fec-adf4-08935c975ed3" xlink:to="loc_us-gaap_OperatingSegmentsMember_2f9a3a3d-577d-4c07-99b1-a9e623c73d07" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_4af809a2-a88a-4c70-b288-32e2675630da" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_a4742a72-3ce4-4fec-adf4-08935c975ed3" xlink:to="loc_us-gaap_CorporateNonSegmentMember_4af809a2-a88a-4c70-b288-32e2675630da" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/SegmentedinformationInformationonOperationsbyGeographicAreaDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#SegmentedinformationInformationonOperationsbyGeographicAreaDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/SegmentedinformationInformationonOperationsbyGeographicAreaDetail" xlink:type="extended" id="ib8472043d4c54af082961720b2c196a3_SegmentedinformationInformationonOperationsbyGeographicAreaDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_f8e5ce2b-9651-4e37-9afd-47f7decb9f9f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_a2005f89-be67-4fe5-a8f6-bcdf9d3421b0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_f8e5ce2b-9651-4e37-9afd-47f7decb9f9f" xlink:to="loc_us-gaap_Revenues_a2005f89-be67-4fe5-a8f6-bcdf9d3421b0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c7131a54-3721-4c60-942a-6f0c8f23829a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_f8e5ce2b-9651-4e37-9afd-47f7decb9f9f" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c7131a54-3721-4c60-942a-6f0c8f23829a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_f7f146e8-b26d-4818-babe-a6c1f6a41b46" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c7131a54-3721-4c60-942a-6f0c8f23829a" xlink:to="loc_srt_StatementGeographicalAxis_f7f146e8-b26d-4818-babe-a6c1f6a41b46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_f7f146e8-b26d-4818-babe-a6c1f6a41b46_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_f7f146e8-b26d-4818-babe-a6c1f6a41b46" xlink:to="loc_srt_SegmentGeographicalDomain_f7f146e8-b26d-4818-babe-a6c1f6a41b46_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_5e704fdb-b16e-44cc-84a2-54fda4790390" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_f7f146e8-b26d-4818-babe-a6c1f6a41b46" xlink:to="loc_srt_SegmentGeographicalDomain_5e704fdb-b16e-44cc-84a2-54fda4790390" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_e71e3333-9ba4-48e0-9300-4112fdfe5797" xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_5e704fdb-b16e-44cc-84a2-54fda4790390" xlink:to="loc_country_US_e71e3333-9ba4-48e0-9300-4112fdfe5797" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CA_478748f1-33e9-4e86-bcb9-53302b512a38" xlink:href="https://xbrl.sec.gov/country/2021/country-2021.xsd#country_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_5e704fdb-b16e-44cc-84a2-54fda4790390" xlink:to="loc_country_CA_478748f1-33e9-4e86-bcb9-53302b512a38" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_InternationalExcludingCanadaMember_4c4549d9-7ed3-47d2-ab7f-49af409289d9" xlink:href="aqunf-20210630.xsd#aqunf_InternationalExcludingCanadaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_5e704fdb-b16e-44cc-84a2-54fda4790390" xlink:to="loc_aqunf_InternationalExcludingCanadaMember_4c4549d9-7ed3-47d2-ab7f-49af409289d9" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/CommitmentsandcontingenciesEstimatesofFutureCommitmentsDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#CommitmentsandcontingenciesEstimatesofFutureCommitmentsDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/CommitmentsandcontingenciesEstimatesofFutureCommitmentsDetail" xlink:type="extended" id="ia4a2f8b24ba04134a8a5035fc4597b09_CommitmentsandcontingenciesEstimatesofFutureCommitmentsDetail">
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CommitmentsDisclosureLineItems_4a4a6c59-53ad-4ee9-ae90-9b5ffa3ba931" xlink:href="aqunf-20210630.xsd#aqunf_CommitmentsDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_WindPowerCapacity_1ec63cf6-6c4d-4310-a730-b60b1b461907" xlink:href="aqunf-20210630.xsd#aqunf_WindPowerCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_CommitmentsDisclosureLineItems_4a4a6c59-53ad-4ee9-ae90-9b5ffa3ba931" xlink:to="loc_aqunf_WindPowerCapacity_1ec63cf6-6c4d-4310-a730-b60b1b461907" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligationDueInNextTwelveMonths_9df89f99-ad5a-4927-8024-e0d369416153" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractualObligationDueInNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_CommitmentsDisclosureLineItems_4a4a6c59-53ad-4ee9-ae90-9b5ffa3ba931" xlink:to="loc_us-gaap_ContractualObligationDueInNextTwelveMonths_9df89f99-ad5a-4927-8024-e0d369416153" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligationDueInSecondYear_e7bcb8a7-2919-40e0-9e24-13013297a9b9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractualObligationDueInSecondYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_CommitmentsDisclosureLineItems_4a4a6c59-53ad-4ee9-ae90-9b5ffa3ba931" xlink:to="loc_us-gaap_ContractualObligationDueInSecondYear_e7bcb8a7-2919-40e0-9e24-13013297a9b9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligationDueInThirdYear_92d2e9a3-e396-4579-bfb0-eaa4d2cb0f99" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractualObligationDueInThirdYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_CommitmentsDisclosureLineItems_4a4a6c59-53ad-4ee9-ae90-9b5ffa3ba931" xlink:to="loc_us-gaap_ContractualObligationDueInThirdYear_92d2e9a3-e396-4579-bfb0-eaa4d2cb0f99" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligationDueInFourthYear_0020fc22-0ade-4a82-8ae3-9d9eb1610b7b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractualObligationDueInFourthYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_CommitmentsDisclosureLineItems_4a4a6c59-53ad-4ee9-ae90-9b5ffa3ba931" xlink:to="loc_us-gaap_ContractualObligationDueInFourthYear_0020fc22-0ade-4a82-8ae3-9d9eb1610b7b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligationDueInFifthYear_6f3c7387-2945-4438-8d25-0d030e2dc0c1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractualObligationDueInFifthYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_CommitmentsDisclosureLineItems_4a4a6c59-53ad-4ee9-ae90-9b5ffa3ba931" xlink:to="loc_us-gaap_ContractualObligationDueInFifthYear_6f3c7387-2945-4438-8d25-0d030e2dc0c1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligationDueAfterFifthYear_1160ab67-a82f-40d2-b782-cbfbcf333353" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractualObligationDueAfterFifthYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_CommitmentsDisclosureLineItems_4a4a6c59-53ad-4ee9-ae90-9b5ffa3ba931" xlink:to="loc_us-gaap_ContractualObligationDueAfterFifthYear_1160ab67-a82f-40d2-b782-cbfbcf333353" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligation_67c192f5-014f-43a9-bdb8-139584cbe22c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ContractualObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_CommitmentsDisclosureLineItems_4a4a6c59-53ad-4ee9-ae90-9b5ffa3ba931" xlink:to="loc_us-gaap_ContractualObligation_67c192f5-014f-43a9-bdb8-139584cbe22c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CommitmentsDisclosureTable_af8d383c-f2c7-4dff-9ac0-c30bd89770b8" xlink:href="aqunf-20210630.xsd#aqunf_CommitmentsDisclosureTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_aqunf_CommitmentsDisclosureLineItems_4a4a6c59-53ad-4ee9-ae90-9b5ffa3ba931" xlink:to="loc_aqunf_CommitmentsDisclosureTable_af8d383c-f2c7-4dff-9ac0-c30bd89770b8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_4c5d7194-6b32-4ee3-b11d-9b3731ecf9b0" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_CommitmentsDisclosureTable_af8d383c-f2c7-4dff-9ac0-c30bd89770b8" xlink:to="loc_srt_LitigationCaseAxis_4c5d7194-6b32-4ee3-b11d-9b3731ecf9b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_4c5d7194-6b32-4ee3-b11d-9b3731ecf9b0_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_4c5d7194-6b32-4ee3-b11d-9b3731ecf9b0" xlink:to="loc_srt_LitigationCaseTypeDomain_4c5d7194-6b32-4ee3-b11d-9b3731ecf9b0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_d543f3b5-121d-4e64-b030-86a4797612ca" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_4c5d7194-6b32-4ee3-b11d-9b3731ecf9b0" xlink:to="loc_srt_LitigationCaseTypeDomain_d543f3b5-121d-4e64-b030-86a4797612ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_GaiaPowerInc.vsAPUCMember_4304f5a3-699e-404c-80d2-72b76bd68973" xlink:href="aqunf-20210630.xsd#aqunf_GaiaPowerInc.vsAPUCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_d543f3b5-121d-4e64-b030-86a4797612ca" xlink:to="loc_aqunf_GaiaPowerInc.vsAPUCMember_4304f5a3-699e-404c-80d2-72b76bd68973" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CommitmentsAxis_4fbad339-2972-47b4-a5ea-ffc6093aa141" xlink:href="aqunf-20210630.xsd#aqunf_CommitmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_CommitmentsDisclosureTable_af8d383c-f2c7-4dff-9ac0-c30bd89770b8" xlink:to="loc_aqunf_CommitmentsAxis_4fbad339-2972-47b4-a5ea-ffc6093aa141" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CommitmentsDomain_4fbad339-2972-47b4-a5ea-ffc6093aa141_default" xlink:href="aqunf-20210630.xsd#aqunf_CommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_aqunf_CommitmentsAxis_4fbad339-2972-47b4-a5ea-ffc6093aa141" xlink:to="loc_aqunf_CommitmentsDomain_4fbad339-2972-47b4-a5ea-ffc6093aa141_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CommitmentsDomain_b1e1dc02-506a-44a9-b88f-9ae8ffb2e390" xlink:href="aqunf-20210630.xsd#aqunf_CommitmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_aqunf_CommitmentsAxis_4fbad339-2972-47b4-a5ea-ffc6093aa141" xlink:to="loc_aqunf_CommitmentsDomain_b1e1dc02-506a-44a9-b88f-9ae8ffb2e390" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_PurchasedPowerMember_1bb6a32c-0545-445d-99ca-296befa75ca3" xlink:href="aqunf-20210630.xsd#aqunf_PurchasedPowerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_CommitmentsDomain_b1e1dc02-506a-44a9-b88f-9ae8ffb2e390" xlink:to="loc_aqunf_PurchasedPowerMember_1bb6a32c-0545-445d-99ca-296befa75ca3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ServicesAndSupplyAgreementMember_07aa281b-aead-4727-a424-1f27c68621a1" xlink:href="aqunf-20210630.xsd#aqunf_ServicesAndSupplyAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_CommitmentsDomain_b1e1dc02-506a-44a9-b88f-9ae8ffb2e390" xlink:to="loc_aqunf_ServicesAndSupplyAgreementMember_07aa281b-aead-4727-a424-1f27c68621a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceAgreementsMember_cdfa4c56-f312-416b-871b-a101087cb21e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ServiceAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_CommitmentsDomain_b1e1dc02-506a-44a9-b88f-9ae8ffb2e390" xlink:to="loc_us-gaap_ServiceAgreementsMember_cdfa4c56-f312-416b-871b-a101087cb21e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CapitalProjectsMember_2067fdc9-694f-405c-9411-4f9126a30717" xlink:href="aqunf-20210630.xsd#aqunf_CapitalProjectsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_CommitmentsDomain_b1e1dc02-506a-44a9-b88f-9ae8ffb2e390" xlink:to="loc_aqunf_CapitalProjectsMember_2067fdc9-694f-405c-9411-4f9126a30717" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_OperatingLeasesMember_c2b976da-ccfe-4f8a-bff2-84e155c00b6c" xlink:href="aqunf-20210630.xsd#aqunf_OperatingLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_CommitmentsDomain_b1e1dc02-506a-44a9-b88f-9ae8ffb2e390" xlink:to="loc_aqunf_OperatingLeasesMember_c2b976da-ccfe-4f8a-bff2-84e155c00b6c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_845273bb-481f-40c8-96c3-ba0f90a05d90" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_CommitmentsDisclosureTable_af8d383c-f2c7-4dff-9ac0-c30bd89770b8" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_845273bb-481f-40c8-96c3-ba0f90a05d90" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_845273bb-481f-40c8-96c3-ba0f90a05d90_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_845273bb-481f-40c8-96c3-ba0f90a05d90" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_845273bb-481f-40c8-96c3-ba0f90a05d90_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_eb6c018b-05d3-4f18-acd7-699402396400" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_845273bb-481f-40c8-96c3-ba0f90a05d90" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_eb6c018b-05d3-4f18-acd7-699402396400" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AmherstIslandWindFacilityMember_1410d9c4-6c86-4378-9cdb-03422606143a" xlink:href="aqunf-20210630.xsd#aqunf_AmherstIslandWindFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_eb6c018b-05d3-4f18-acd7-699402396400" xlink:to="loc_aqunf_AmherstIslandWindFacilityMember_1410d9c4-6c86-4378-9cdb-03422606143a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_BlueHillWindProjectMember_8002d27e-d5bd-4211-8a1f-accf93c1361a" xlink:href="aqunf-20210630.xsd#aqunf_BlueHillWindProjectMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_eb6c018b-05d3-4f18-acd7-699402396400" xlink:to="loc_aqunf_BlueHillWindProjectMember_8002d27e-d5bd-4211-8a1f-accf93c1361a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_acd50c1d-52b2-4ccd-9aed-dbcd0cf43c1d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_CommitmentsDisclosureTable_af8d383c-f2c7-4dff-9ac0-c30bd89770b8" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_acd50c1d-52b2-4ccd-9aed-dbcd0cf43c1d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_acd50c1d-52b2-4ccd-9aed-dbcd0cf43c1d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_acd50c1d-52b2-4ccd-9aed-dbcd0cf43c1d" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_acd50c1d-52b2-4ccd-9aed-dbcd0cf43c1d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_73973d3f-24df-4884-aa70-d843e9410726" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_acd50c1d-52b2-4ccd-9aed-dbcd0cf43c1d" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_73973d3f-24df-4884-aa70-d843e9410726" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_62173e65-89d3-4f37-aba5-0bd8a64ae11b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_73973d3f-24df-4884-aa70-d843e9410726" xlink:to="loc_us-gaap_SubsequentEventMember_62173e65-89d3-4f37-aba5-0bd8a64ae11b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/FinancialinstrumentsFairValueofFinancialInstrumentsDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#FinancialinstrumentsFairValueofFinancialInstrumentsDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/FinancialinstrumentsFairValueofFinancialInstrumentsDetail" xlink:type="extended" id="i3bfccb62992042608c25353dd44c9ace_FinancialinstrumentsFairValueofFinancialInstrumentsDetail">
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_a0ad2d88-76e8-4eb9-814c-e40a71ad23d1" xlink:href="aqunf-20210630.xsd#aqunf_FairValueOfFinancialInstrumentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_LongtermInvestmentsFairValue_8bd58b38-cad4-4434-b3ea-98963031834f" xlink:href="aqunf-20210630.xsd#aqunf_LongtermInvestmentsFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_a0ad2d88-76e8-4eb9-814c-e40a71ad23d1" xlink:to="loc_aqunf_LongtermInvestmentsFairValue_8bd58b38-cad4-4434-b3ea-98963031834f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesReceivableFairValueDisclosure_021f58ba-01a8-4d2b-9cf9-0d4d7d6af332" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NotesReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_a0ad2d88-76e8-4eb9-814c-e40a71ad23d1" xlink:to="loc_us-gaap_NotesReceivableFairValueDisclosure_021f58ba-01a8-4d2b-9cf9-0d4d7d6af332" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_7babd44b-f55d-47fd-b2ad-8d5f28b1c5e2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_a0ad2d88-76e8-4eb9-814c-e40a71ad23d1" xlink:to="loc_us-gaap_DerivativeAssets_7babd44b-f55d-47fd-b2ad-8d5f28b1c5e2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_f4bf1563-0b5c-4beb-b024-ade53b5d5c25" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_a0ad2d88-76e8-4eb9-814c-e40a71ad23d1" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_f4bf1563-0b5c-4beb-b024-ade53b5d5c25" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_31d75e87-3197-4e1d-b502-34eb2315ee50" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_a0ad2d88-76e8-4eb9-814c-e40a71ad23d1" xlink:to="loc_us-gaap_LongTermDebtFairValue_31d75e87-3197-4e1d-b502-34eb2315ee50" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableRelatedPartiesCurrentAndNoncurrent_f3c4028a-e797-4092-ac48-f23f223b0302" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NotesPayableRelatedPartiesCurrentAndNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_a0ad2d88-76e8-4eb9-814c-e40a71ad23d1" xlink:to="loc_us-gaap_NotesPayableRelatedPartiesCurrentAndNoncurrent_f3c4028a-e797-4092-ac48-f23f223b0302" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtFairValueDisclosures_c9d6eaaf-d1f1-4718-8793-8b760a2fc4f1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConvertibleDebtFairValueDisclosures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_a0ad2d88-76e8-4eb9-814c-e40a71ad23d1" xlink:to="loc_us-gaap_ConvertibleDebtFairValueDisclosures_c9d6eaaf-d1f1-4718-8793-8b760a2fc4f1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MandatorilyRedeemablePreferredStockFairValueDisclosure_0e899ab3-543a-4588-b3ee-d260ec08a383" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MandatorilyRedeemablePreferredStockFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_a0ad2d88-76e8-4eb9-814c-e40a71ad23d1" xlink:to="loc_us-gaap_MandatorilyRedeemablePreferredStockFairValueDisclosure_0e899ab3-543a-4588-b3ee-d260ec08a383" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_934673fb-a3d8-43ea-9e96-eb7177908378" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_a0ad2d88-76e8-4eb9-814c-e40a71ad23d1" xlink:to="loc_us-gaap_DerivativeLiabilities_934673fb-a3d8-43ea-9e96-eb7177908378" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_cc7eae8e-3f13-48ef-a632-6e9e65fd7d6f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_a0ad2d88-76e8-4eb9-814c-e40a71ad23d1" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_cc7eae8e-3f13-48ef-a632-6e9e65fd7d6f" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_FairValueOfFinancialInstrumentsTable_ab70c88f-bb35-416b-9935-95e6dd43c3e4" xlink:href="aqunf-20210630.xsd#aqunf_FairValueOfFinancialInstrumentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_a0ad2d88-76e8-4eb9-814c-e40a71ad23d1" xlink:to="loc_aqunf_FairValueOfFinancialInstrumentsTable_ab70c88f-bb35-416b-9935-95e6dd43c3e4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_bde75afd-da44-46bd-8c6e-396348ee0ff4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_ab70c88f-bb35-416b-9935-95e6dd43c3e4" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_bde75afd-da44-46bd-8c6e-396348ee0ff4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_bde75afd-da44-46bd-8c6e-396348ee0ff4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_bde75afd-da44-46bd-8c6e-396348ee0ff4" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_bde75afd-da44-46bd-8c6e-396348ee0ff4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_208f0eba-20b0-4184-a245-000499f3be4d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_bde75afd-da44-46bd-8c6e-396348ee0ff4" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_208f0eba-20b0-4184-a245-000499f3be4d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_5045b333-e3c4-4d3a-bccc-9053daa88849" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_208f0eba-20b0-4184-a245-000499f3be4d" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_5045b333-e3c4-4d3a-bccc-9053daa88849" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_182e508a-555f-444f-ba20-f501320df0a4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_5045b333-e3c4-4d3a-bccc-9053daa88849" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_182e508a-555f-444f-ba20-f501320df0a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_f520b415-07ec-4dbc-9a27-f1333f7e0b1e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_5045b333-e3c4-4d3a-bccc-9053daa88849" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_f520b415-07ec-4dbc-9a27-f1333f7e0b1e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_67af9716-9cf1-46e3-bf96-fb8811ec4779" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_ab70c88f-bb35-416b-9935-95e6dd43c3e4" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_67af9716-9cf1-46e3-bf96-fb8811ec4779" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_67af9716-9cf1-46e3-bf96-fb8811ec4779_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_67af9716-9cf1-46e3-bf96-fb8811ec4779" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_67af9716-9cf1-46e3-bf96-fb8811ec4779_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2065b798-80b1-4b1c-bc94-e759a541bb88" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_67af9716-9cf1-46e3-bf96-fb8811ec4779" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2065b798-80b1-4b1c-bc94-e759a541bb88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_d88c2a7b-6847-4e36-af5e-e1c16024be11" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2065b798-80b1-4b1c-bc94-e759a541bb88" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_d88c2a7b-6847-4e36-af5e-e1c16024be11" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_780be794-7d95-474a-9bbb-b7c0c845a558" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2065b798-80b1-4b1c-bc94-e759a541bb88" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_780be794-7d95-474a-9bbb-b7c0c845a558" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_f9a1be19-9248-44ba-8636-da6607e8c918" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2065b798-80b1-4b1c-bc94-e759a541bb88" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_f9a1be19-9248-44ba-8636-da6607e8c918" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_f5887de3-cd3f-4397-8bde-94aed9e40039" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_ab70c88f-bb35-416b-9935-95e6dd43c3e4" xlink:to="loc_us-gaap_StatementClassOfStockAxis_f5887de3-cd3f-4397-8bde-94aed9e40039" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_f5887de3-cd3f-4397-8bde-94aed9e40039_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_f5887de3-cd3f-4397-8bde-94aed9e40039" xlink:to="loc_us-gaap_ClassOfStockDomain_f5887de3-cd3f-4397-8bde-94aed9e40039_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_1779420c-29c9-4ccb-8b1d-5399ed9d81d5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_f5887de3-cd3f-4397-8bde-94aed9e40039" xlink:to="loc_us-gaap_ClassOfStockDomain_1779420c-29c9-4ccb-8b1d-5399ed9d81d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesCPreferredStockMember_73f2b12b-c782-46fe-8995-553c24dad23f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SeriesCPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_1779420c-29c9-4ccb-8b1d-5399ed9d81d5" xlink:to="loc_us-gaap_SeriesCPreferredStockMember_73f2b12b-c782-46fe-8995-553c24dad23f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_77940bf8-9c12-4056-82eb-73d6ba5e1873" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_ab70c88f-bb35-416b-9935-95e6dd43c3e4" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_77940bf8-9c12-4056-82eb-73d6ba5e1873" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_77940bf8-9c12-4056-82eb-73d6ba5e1873_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_77940bf8-9c12-4056-82eb-73d6ba5e1873" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_77940bf8-9c12-4056-82eb-73d6ba5e1873_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_e222d47c-87a2-49d3-a6f5-4fdab96c8dfe" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_77940bf8-9c12-4056-82eb-73d6ba5e1873" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_e222d47c-87a2-49d3-a6f5-4fdab96c8dfe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnergyRelatedDerivativeMember_5c26a1fd-5ba6-450b-8d0b-1dc94b801e56" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EnergyRelatedDerivativeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_e222d47c-87a2-49d3-a6f5-4fdab96c8dfe" xlink:to="loc_us-gaap_EnergyRelatedDerivativeMember_5c26a1fd-5ba6-450b-8d0b-1dc94b801e56" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_d5aa7748-ea57-45cd-b3fc-5780cc92838b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_e222d47c-87a2-49d3-a6f5-4fdab96c8dfe" xlink:to="loc_us-gaap_InterestRateSwapMember_d5aa7748-ea57-45cd-b3fc-5780cc92838b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_5e8ecd96-fe0c-46b6-a754-d78c5a77e997" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_e222d47c-87a2-49d3-a6f5-4fdab96c8dfe" xlink:to="loc_us-gaap_CommodityContractMember_5e8ecd96-fe0c-46b6-a754-d78c5a77e997" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_8f3c1059-0ada-4b18-814e-ebbd215f190b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_e222d47c-87a2-49d3-a6f5-4fdab96c8dfe" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_8f3c1059-0ada-4b18-814e-ebbd215f190b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_a9b2589e-877a-4306-be7c-29c42ba0e4f8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_ab70c88f-bb35-416b-9935-95e6dd43c3e4" xlink:to="loc_us-gaap_HedgingDesignationAxis_a9b2589e-877a-4306-be7c-29c42ba0e4f8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_a9b2589e-877a-4306-be7c-29c42ba0e4f8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_a9b2589e-877a-4306-be7c-29c42ba0e4f8" xlink:to="loc_us-gaap_HedgingDesignationDomain_a9b2589e-877a-4306-be7c-29c42ba0e4f8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_bb06a405-f9f0-4681-a501-ec4353c4cac4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_a9b2589e-877a-4306-be7c-29c42ba0e4f8" xlink:to="loc_us-gaap_HedgingDesignationDomain_bb06a405-f9f0-4681-a501-ec4353c4cac4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_96628d31-50c4-45a9-8c92-6a2004442bd8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_bb06a405-f9f0-4681-a501-ec4353c4cac4" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_96628d31-50c4-45a9-8c92-6a2004442bd8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_43c5d19f-f154-42a5-8620-b6a193d20c93" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_bb06a405-f9f0-4681-a501-ec4353c4cac4" xlink:to="loc_us-gaap_NondesignatedMember_43c5d19f-f154-42a5-8620-b6a193d20c93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_8a24eba5-dd9f-4fab-b851-f301f798e9b6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_ab70c88f-bb35-416b-9935-95e6dd43c3e4" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_8a24eba5-dd9f-4fab-b851-f301f798e9b6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_8a24eba5-dd9f-4fab-b851-f301f798e9b6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_8a24eba5-dd9f-4fab-b851-f301f798e9b6" xlink:to="loc_us-gaap_HedgingRelationshipDomain_8a24eba5-dd9f-4fab-b851-f301f798e9b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_323c146c-30bb-4cc1-9370-09de6a0118a1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_8a24eba5-dd9f-4fab-b851-f301f798e9b6" xlink:to="loc_us-gaap_HedgingRelationshipDomain_323c146c-30bb-4cc1-9370-09de6a0118a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_00376c09-37ef-41c3-9526-859171a48b52" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_323c146c-30bb-4cc1-9370-09de6a0118a1" xlink:to="loc_us-gaap_CashFlowHedgingMember_00376c09-37ef-41c3-9526-859171a48b52" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_4a4b48e9-1496-4cf4-b0db-54e353933bcb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_323c146c-30bb-4cc1-9370-09de6a0118a1" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_4a4b48e9-1496-4cf4-b0db-54e353933bcb" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/FinancialinstrumentsAdditionalInformationDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#FinancialinstrumentsAdditionalInformationDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/FinancialinstrumentsAdditionalInformationDetail" xlink:type="extended" id="i451df18e7e6d4267875d9bece15b4d40_FinancialinstrumentsAdditionalInformationDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_ef7c6a93-7c08-4e3e-9ef3-17ec39e0341d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeForwardPrice_a6150009-8fdd-432b-9d39-2d19dac9bbb3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeForwardPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ef7c6a93-7c08-4e3e-9ef3-17ec39e0341d" xlink:to="loc_us-gaap_DerivativeForwardPrice_a6150009-8fdd-432b-9d39-2d19dac9bbb3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AlternativeInvestmentMeasurementInput_433e8f65-80ea-448b-994d-c2101b56e83c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AlternativeInvestmentMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ef7c6a93-7c08-4e3e-9ef3-17ec39e0341d" xlink:to="loc_us-gaap_AlternativeInvestmentMeasurementInput_433e8f65-80ea-448b-994d-c2101b56e83c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure_f946a83f-9ae2-43e4-bd6e-3948f327e907" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ef7c6a93-7c08-4e3e-9ef3-17ec39e0341d" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure_f946a83f-9ae2-43e4-bd6e-3948f327e907" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CostperMegawattHour_10c8cb51-a02c-4971-81c4-9ce199920190" xlink:href="aqunf-20210630.xsd#aqunf_CostperMegawattHour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ef7c6a93-7c08-4e3e-9ef3-17ec39e0341d" xlink:to="loc_aqunf_CostperMegawattHour_10c8cb51-a02c-4971-81c4-9ce199920190" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NumberOfInterestRateSwapsRedesignatedAsCashFlowHedges_a6091127-4ec6-4f72-ae13-2c3830dbc1ee" xlink:href="aqunf-20210630.xsd#aqunf_NumberOfInterestRateSwapsRedesignatedAsCashFlowHedges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ef7c6a93-7c08-4e3e-9ef3-17ec39e0341d" xlink:to="loc_aqunf_NumberOfInterestRateSwapsRedesignatedAsCashFlowHedges_a6091127-4ec6-4f72-ae13-2c3830dbc1ee" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_53368709-d1e0-49a6-85f4-14b2cf41dad2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ef7c6a93-7c08-4e3e-9ef3-17ec39e0341d" xlink:to="loc_us-gaap_DerivativeNotionalAmount_53368709-d1e0-49a6-85f4-14b2cf41dad2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFixedInterestRate_ccec06dd-d619-4cc0-b8c1-c609c1cbe819" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeFixedInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ef7c6a93-7c08-4e3e-9ef3-17ec39e0341d" xlink:to="loc_us-gaap_DerivativeFixedInterestRate_ccec06dd-d619-4cc0-b8c1-c609c1cbe819" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NumberOfTermLoanFacilities_52d60883-3a83-4299-91aa-10ada7fb1d3b" xlink:href="aqunf-20210630.xsd#aqunf_NumberOfTermLoanFacilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ef7c6a93-7c08-4e3e-9ef3-17ec39e0341d" xlink:to="loc_aqunf_NumberOfTermLoanFacilities_52d60883-3a83-4299-91aa-10ada7fb1d3b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTermOfContract_4b2ac6f5-5ad1-4617-b166-eef4788f84b0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ef7c6a93-7c08-4e3e-9ef3-17ec39e0341d" xlink:to="loc_us-gaap_DerivativeTermOfContract_4b2ac6f5-5ad1-4617-b166-eef4788f84b0" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_2fafeac7-b18b-42fd-91be-ee14a2eb11f6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ef7c6a93-7c08-4e3e-9ef3-17ec39e0341d" xlink:to="loc_us-gaap_DebtInstrumentTerm_2fafeac7-b18b-42fd-91be-ee14a2eb11f6" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths_21de3c1c-f0dd-4b8c-a980-0413c18bc819" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ef7c6a93-7c08-4e3e-9ef3-17ec39e0341d" xlink:to="loc_us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths_21de3c1c-f0dd-4b8c-a980-0413c18bc819" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_627c18b7-b7b9-40e5-83ee-204daa9bcfaa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ef7c6a93-7c08-4e3e-9ef3-17ec39e0341d" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_627c18b7-b7b9-40e5-83ee-204daa9bcfaa" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_99db85a5-884c-448a-9b36-fd56ad749d44" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ef7c6a93-7c08-4e3e-9ef3-17ec39e0341d" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_99db85a5-884c-448a-9b36-fd56ad749d44" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ExtinguishmentOfDebtAmount_abd8c7dd-a9ab-45ee-a7ea-87dfbdecbd0b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ExtinguishmentOfDebtAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ef7c6a93-7c08-4e3e-9ef3-17ec39e0341d" xlink:to="loc_us-gaap_ExtinguishmentOfDebtAmount_abd8c7dd-a9ab-45ee-a7ea-87dfbdecbd0b" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_FairValueOfFinancialInstrumentsTable_c6fb536a-cac9-44c8-85ab-c960ec6bc85c" xlink:href="aqunf-20210630.xsd#aqunf_FairValueOfFinancialInstrumentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_ef7c6a93-7c08-4e3e-9ef3-17ec39e0341d" xlink:to="loc_aqunf_FairValueOfFinancialInstrumentsTable_c6fb536a-cac9-44c8-85ab-c960ec6bc85c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_0964b4c1-4f59-4d8a-9be2-c2be4351e14d" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_c6fb536a-cac9-44c8-85ab-c960ec6bc85c" xlink:to="loc_srt_RangeAxis_0964b4c1-4f59-4d8a-9be2-c2be4351e14d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_0964b4c1-4f59-4d8a-9be2-c2be4351e14d_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_0964b4c1-4f59-4d8a-9be2-c2be4351e14d" xlink:to="loc_srt_RangeMember_0964b4c1-4f59-4d8a-9be2-c2be4351e14d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_f7f7c4df-3cf4-406e-bf0d-6ea432746a98" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_0964b4c1-4f59-4d8a-9be2-c2be4351e14d" xlink:to="loc_srt_RangeMember_f7f7c4df-3cf4-406e-bf0d-6ea432746a98" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_532abdde-c920-4194-8623-a02caef4b187" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_f7f7c4df-3cf4-406e-bf0d-6ea432746a98" xlink:to="loc_srt_MinimumMember_532abdde-c920-4194-8623-a02caef4b187" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_83373721-acce-4792-97dd-4e7e763cfd9e" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_f7f7c4df-3cf4-406e-bf0d-6ea432746a98" xlink:to="loc_srt_MaximumMember_83373721-acce-4792-97dd-4e7e763cfd9e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_WeightedAverageMember_037356f5-ab1d-43ea-a055-bef4b9735557" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_WeightedAverageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_f7f7c4df-3cf4-406e-bf0d-6ea432746a98" xlink:to="loc_srt_WeightedAverageMember_037356f5-ab1d-43ea-a055-bef4b9735557" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_31090433-0a05-408c-97f1-94924caa78fe" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_c6fb536a-cac9-44c8-85ab-c960ec6bc85c" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_31090433-0a05-408c-97f1-94924caa78fe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_31090433-0a05-408c-97f1-94924caa78fe_default" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_31090433-0a05-408c-97f1-94924caa78fe" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_31090433-0a05-408c-97f1-94924caa78fe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_5385bf3c-2ac9-4c47-b455-8e6830567732" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_31090433-0a05-408c-97f1-94924caa78fe" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_5385bf3c-2ac9-4c47-b455-8e6830567732" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AYESCanadaMember_a6e86acd-36d6-43e1-8a2f-7f711dded96b" xlink:href="aqunf-20210630.xsd#aqunf_AYESCanadaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_5385bf3c-2ac9-4c47-b455-8e6830567732" xlink:to="loc_aqunf_AYESCanadaMember_a6e86acd-36d6-43e1-8a2f-7f711dded96b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AtlanticaYieldEnergySolutionsCanadaInc.Member_72aff39f-fa38-4b98-9e51-a999fb5cd4ac" xlink:href="aqunf-20210630.xsd#aqunf_AtlanticaYieldEnergySolutionsCanadaInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_5385bf3c-2ac9-4c47-b455-8e6830567732" xlink:to="loc_aqunf_AtlanticaYieldEnergySolutionsCanadaInc.Member_72aff39f-fa38-4b98-9e51-a999fb5cd4ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CanadianInvestmentsandSubsidiariesMember_c7250b3a-5d8f-4674-8c92-894eec888edd" xlink:href="aqunf-20210630.xsd#aqunf_CanadianInvestmentsandSubsidiariesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_5385bf3c-2ac9-4c47-b455-8e6830567732" xlink:to="loc_aqunf_CanadianInvestmentsandSubsidiariesMember_c7250b3a-5d8f-4674-8c92-894eec888edd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_9b8431b9-26f8-4bd6-b469-8ecebd7e7b07" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_c6fb536a-cac9-44c8-85ab-c960ec6bc85c" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_9b8431b9-26f8-4bd6-b469-8ecebd7e7b07" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_9b8431b9-26f8-4bd6-b469-8ecebd7e7b07_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_9b8431b9-26f8-4bd6-b469-8ecebd7e7b07" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_9b8431b9-26f8-4bd6-b469-8ecebd7e7b07_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_40b0b004-23f4-4a7a-8d0d-0b930d8e7143" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_9b8431b9-26f8-4bd6-b469-8ecebd7e7b07" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_40b0b004-23f4-4a7a-8d0d-0b930d8e7143" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_a92af8f6-cb8a-4b49-9d67-020c8ea079bc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_40b0b004-23f4-4a7a-8d0d-0b930d8e7143" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_a92af8f6-cb8a-4b49-9d67-020c8ea079bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputPriceVolatilityMember_c7de0108-64b8-4894-9982-9cdff4a9d8e5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MeasurementInputPriceVolatilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_40b0b004-23f4-4a7a-8d0d-0b930d8e7143" xlink:to="loc_us-gaap_MeasurementInputPriceVolatilityMember_c7de0108-64b8-4894-9982-9cdff4a9d8e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_c0dde336-576a-4307-9ace-3c0f905b43c2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_c6fb536a-cac9-44c8-85ab-c960ec6bc85c" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_c0dde336-576a-4307-9ace-3c0f905b43c2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_c0dde336-576a-4307-9ace-3c0f905b43c2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_c0dde336-576a-4307-9ace-3c0f905b43c2" xlink:to="loc_us-gaap_HedgingRelationshipDomain_c0dde336-576a-4307-9ace-3c0f905b43c2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_5d9f46cf-47bf-42b4-b68a-b0009651d8b0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_c0dde336-576a-4307-9ace-3c0f905b43c2" xlink:to="loc_us-gaap_HedgingRelationshipDomain_5d9f46cf-47bf-42b4-b68a-b0009651d8b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_0217de19-24b9-43ae-b9db-31118fc40d92" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_5d9f46cf-47bf-42b4-b68a-b0009651d8b0" xlink:to="loc_us-gaap_CashFlowHedgingMember_0217de19-24b9-43ae-b9db-31118fc40d92" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerAxis_4ce2e44b-fabf-4e77-9a32-960256ac58bd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermContractForPurchaseOfElectricPowerAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_c6fb536a-cac9-44c8-85ab-c960ec6bc85c" xlink:to="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerAxis_4ce2e44b-fabf-4e77-9a32-960256ac58bd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerDomain_4ce2e44b-fabf-4e77-9a32-960256ac58bd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermContractForPurchaseOfElectricPowerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerAxis_4ce2e44b-fabf-4e77-9a32-960256ac58bd" xlink:to="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerDomain_4ce2e44b-fabf-4e77-9a32-960256ac58bd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerDomain_f964b207-e3db-405e-86d1-5725718199ef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermContractForPurchaseOfElectricPowerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerAxis_4ce2e44b-fabf-4e77-9a32-960256ac58bd" xlink:to="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerDomain_f964b207-e3db-405e-86d1-5725718199ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ISONESpotRateContractExpiringFebruary2022Member_198b9905-0a93-4a96-b4f0-60efcae5be5b" xlink:href="aqunf-20210630.xsd#aqunf_ISONESpotRateContractExpiringFebruary2022Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerDomain_f964b207-e3db-405e-86d1-5725718199ef" xlink:to="loc_aqunf_ISONESpotRateContractExpiringFebruary2022Member_198b9905-0a93-4a96-b4f0-60efcae5be5b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_983011a8-25d6-47c4-8f33-38ae14b0dd5c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_c6fb536a-cac9-44c8-85ab-c960ec6bc85c" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_983011a8-25d6-47c4-8f33-38ae14b0dd5c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_983011a8-25d6-47c4-8f33-38ae14b0dd5c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_983011a8-25d6-47c4-8f33-38ae14b0dd5c" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_983011a8-25d6-47c4-8f33-38ae14b0dd5c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8cbe72b7-0185-4baa-8e07-227cc2b424e0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_983011a8-25d6-47c4-8f33-38ae14b0dd5c" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8cbe72b7-0185-4baa-8e07-227cc2b424e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_AscendantMember_0647d726-c9c2-47d9-9de2-dec8a8e5e02d" xlink:href="aqunf-20210630.xsd#aqunf_AscendantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8cbe72b7-0185-4baa-8e07-227cc2b424e0" xlink:to="loc_aqunf_AscendantMember_0647d726-c9c2-47d9-9de2-dec8a8e5e02d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_f13d2673-ad4c-497d-8f3e-ec3a5b7d71c6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_c6fb536a-cac9-44c8-85ab-c960ec6bc85c" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_f13d2673-ad4c-497d-8f3e-ec3a5b7d71c6" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_f13d2673-ad4c-497d-8f3e-ec3a5b7d71c6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_f13d2673-ad4c-497d-8f3e-ec3a5b7d71c6" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_f13d2673-ad4c-497d-8f3e-ec3a5b7d71c6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_a42bc339-7550-40ed-b3c0-0ba9a4d56404" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_f13d2673-ad4c-497d-8f3e-ec3a5b7d71c6" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_a42bc339-7550-40ed-b3c0-0ba9a4d56404" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_InterestRateSwapOneMember_4cf2d03d-7dcf-4ec8-9cc3-d6e92cdb6f91" xlink:href="aqunf-20210630.xsd#aqunf_InterestRateSwapOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_a42bc339-7550-40ed-b3c0-0ba9a4d56404" xlink:to="loc_aqunf_InterestRateSwapOneMember_4cf2d03d-7dcf-4ec8-9cc3-d6e92cdb6f91" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_InterestRateSwapTwoMember_c18054e3-d677-4591-beac-4d24333e8d5b" xlink:href="aqunf-20210630.xsd#aqunf_InterestRateSwapTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_a42bc339-7550-40ed-b3c0-0ba9a4d56404" xlink:to="loc_aqunf_InterestRateSwapTwoMember_c18054e3-d677-4591-beac-4d24333e8d5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_5056f7c3-25d6-462d-b3c5-f9d4cfa68d29" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_a42bc339-7550-40ed-b3c0-0ba9a4d56404" xlink:to="loc_us-gaap_InterestRateSwapMember_5056f7c3-25d6-462d-b3c5-f9d4cfa68d29" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrencySwapMember_ba250993-2c80-4650-bf00-7db54d38a7b3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CurrencySwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_a42bc339-7550-40ed-b3c0-0ba9a4d56404" xlink:to="loc_us-gaap_CurrencySwapMember_ba250993-2c80-4650-bf00-7db54d38a7b3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_e181d986-9834-4a77-8646-f0669fa1233a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_a42bc339-7550-40ed-b3c0-0ba9a4d56404" xlink:to="loc_us-gaap_ForeignExchangeContractMember_e181d986-9834-4a77-8646-f0669fa1233a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_556f72c5-88eb-4105-bd0d-17aac5404c65" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_a42bc339-7550-40ed-b3c0-0ba9a4d56404" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_556f72c5-88eb-4105-bd0d-17aac5404c65" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_e7059ae6-bbc3-4f18-b1f2-d9671b3c1a8f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_c6fb536a-cac9-44c8-85ab-c960ec6bc85c" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_e7059ae6-bbc3-4f18-b1f2-d9671b3c1a8f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_e7059ae6-bbc3-4f18-b1f2-d9671b3c1a8f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_e7059ae6-bbc3-4f18-b1f2-d9671b3c1a8f" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_e7059ae6-bbc3-4f18-b1f2-d9671b3c1a8f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_0e1de71b-2db0-4bc1-9960-69f9267c6e0e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_e7059ae6-bbc3-4f18-b1f2-d9671b3c1a8f" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_0e1de71b-2db0-4bc1-9960-69f9267c6e0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NonregulatedEnergySalesMember_fc8a0f87-9155-474f-8b62-19e23974c2e6" xlink:href="aqunf-20210630.xsd#aqunf_NonregulatedEnergySalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_0e1de71b-2db0-4bc1-9960-69f9267c6e0e" xlink:to="loc_aqunf_NonregulatedEnergySalesMember_fc8a0f87-9155-474f-8b62-19e23974c2e6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseMember_0740503b-fe58-4f20-a9fb-a521b6a579ec" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_0e1de71b-2db0-4bc1-9960-69f9267c6e0e" xlink:to="loc_us-gaap_InterestExpenseMember_0740503b-fe58-4f20-a9fb-a521b6a579ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDerivativeInstrumentsMember_1c450702-d201-408e-8a53-d8dd5f03e58b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainLossOnDerivativeInstrumentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_0e1de71b-2db0-4bc1-9960-69f9267c6e0e" xlink:to="loc_us-gaap_GainLossOnDerivativeInstrumentsMember_1c450702-d201-408e-8a53-d8dd5f03e58b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_d95cf135-04b9-4c18-b0a1-91fc8b1fbaba" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_c6fb536a-cac9-44c8-85ab-c960ec6bc85c" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_d95cf135-04b9-4c18-b0a1-91fc8b1fbaba" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_d95cf135-04b9-4c18-b0a1-91fc8b1fbaba_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_d95cf135-04b9-4c18-b0a1-91fc8b1fbaba" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_d95cf135-04b9-4c18-b0a1-91fc8b1fbaba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_34e3836c-763b-4795-b976-0cfaf4e2ea00" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_d95cf135-04b9-4c18-b0a1-91fc8b1fbaba" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_34e3836c-763b-4795-b976-0cfaf4e2ea00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BondsMember_d4179994-281f-42ba-8f51-a6fcc976a9bd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BondsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_34e3836c-763b-4795-b976-0cfaf4e2ea00" xlink:to="loc_us-gaap_BondsMember_d4179994-281f-42ba-8f51-a6fcc976a9bd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnsecuredDebtMember_d1f6f684-a175-46e2-9af9-a467773b1a65" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnsecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_34e3836c-763b-4795-b976-0cfaf4e2ea00" xlink:to="loc_us-gaap_UnsecuredDebtMember_d1f6f684-a175-46e2-9af9-a467773b1a65" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_2c448178-986d-4192-b8fe-cdf54b44eba3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_c6fb536a-cac9-44c8-85ab-c960ec6bc85c" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_2c448178-986d-4192-b8fe-cdf54b44eba3" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_2c448178-986d-4192-b8fe-cdf54b44eba3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_2c448178-986d-4192-b8fe-cdf54b44eba3" xlink:to="loc_us-gaap_SegmentDomain_2c448178-986d-4192-b8fe-cdf54b44eba3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_6bbcf28c-4833-4829-a878-b8391372adb1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_2c448178-986d-4192-b8fe-cdf54b44eba3" xlink:to="loc_us-gaap_SegmentDomain_6bbcf28c-4833-4829-a878-b8391372adb1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_GenerationMember_692cb28c-a9d5-49b4-a3fd-bb3753444504" xlink:href="aqunf-20210630.xsd#aqunf_GenerationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_6bbcf28c-4833-4829-a878-b8391372adb1" xlink:to="loc_aqunf_GenerationMember_692cb28c-a9d5-49b4-a3fd-bb3753444504" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_c5b22073-6530-453c-96c7-2ca5867fb3ab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_c6fb536a-cac9-44c8-85ab-c960ec6bc85c" xlink:to="loc_us-gaap_DebtInstrumentAxis_c5b22073-6530-453c-96c7-2ca5867fb3ab" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_c5b22073-6530-453c-96c7-2ca5867fb3ab_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_c5b22073-6530-453c-96c7-2ca5867fb3ab" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_c5b22073-6530-453c-96c7-2ca5867fb3ab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_2e44ee8f-c944-4aec-8b30-c2d59e03c31c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_c5b22073-6530-453c-96c7-2ca5867fb3ab" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_2e44ee8f-c944-4aec-8b30-c2d59e03c31c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_U.S.DollarSubordinatedUnsecuredNotesMember_6183d517-09c5-4380-97b2-9f615e748a3d" xlink:href="aqunf-20210630.xsd#aqunf_U.S.DollarSubordinatedUnsecuredNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_2e44ee8f-c944-4aec-8b30-c2d59e03c31c" xlink:to="loc_aqunf_U.S.DollarSubordinatedUnsecuredNotesMember_6183d517-09c5-4380-97b2-9f615e748a3d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_SeniorUnsecuredNotesDueJanuary2029Member_e2524e03-4edd-455b-9730-fb7a372e0850" xlink:href="aqunf-20210630.xsd#aqunf_SeniorUnsecuredNotesDueJanuary2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_2e44ee8f-c944-4aec-8b30-c2d59e03c31c" xlink:to="loc_aqunf_SeniorUnsecuredNotesDueJanuary2029Member_e2524e03-4edd-455b-9730-fb7a372e0850" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_CanadianDollarSeniorUnsecuredNotesMember_ac4b4870-258a-40ea-a631-af214746bfec" xlink:href="aqunf-20210630.xsd#aqunf_CanadianDollarSeniorUnsecuredNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_2e44ee8f-c944-4aec-8b30-c2d59e03c31c" xlink:to="loc_aqunf_CanadianDollarSeniorUnsecuredNotesMember_ac4b4870-258a-40ea-a631-af214746bfec" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/FinancialinstrumentsSummaryofCommodityVolumesAssociatedwithDerivativeContractsDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#FinancialinstrumentsSummaryofCommodityVolumesAssociatedwithDerivativeContractsDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/FinancialinstrumentsSummaryofCommodityVolumesAssociatedwithDerivativeContractsDetail" xlink:type="extended" id="i057596c00a604f02871eb7d8822e9885_FinancialinstrumentsSummaryofCommodityVolumesAssociatedwithDerivativeContractsDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_7eaccf82-e066-4302-9b58-dcfa6c0a69cd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_VolumeOfEnergyCommodityContractsNaturalGas_961038c2-0213-4378-b791-14e5bc163d6f" xlink:href="aqunf-20210630.xsd#aqunf_VolumeOfEnergyCommodityContractsNaturalGas"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_7eaccf82-e066-4302-9b58-dcfa6c0a69cd" xlink:to="loc_aqunf_VolumeOfEnergyCommodityContractsNaturalGas_961038c2-0213-4378-b791-14e5bc163d6f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_5f523482-8d0d-42a0-92c0-32f160507c23" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_7eaccf82-e066-4302-9b58-dcfa6c0a69cd" xlink:to="loc_us-gaap_DerivativeTable_5f523482-8d0d-42a0-92c0-32f160507c23" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_ad2068ff-3755-4026-a88b-5d4f8cd6b82e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_5f523482-8d0d-42a0-92c0-32f160507c23" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_ad2068ff-3755-4026-a88b-5d4f8cd6b82e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_ad2068ff-3755-4026-a88b-5d4f8cd6b82e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_ad2068ff-3755-4026-a88b-5d4f8cd6b82e" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_ad2068ff-3755-4026-a88b-5d4f8cd6b82e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_e157ce62-5e8b-4875-8009-6829de048e7b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_ad2068ff-3755-4026-a88b-5d4f8cd6b82e" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_e157ce62-5e8b-4875-8009-6829de048e7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SwapMember_f4714a64-c715-44d3-81ae-32b591db6721" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_e157ce62-5e8b-4875-8009-6829de048e7b" xlink:to="loc_us-gaap_SwapMember_f4714a64-c715-44d3-81ae-32b591db6721" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForwardContractsMember_01e492f1-3e3b-43bc-8b2e-99e0335884ee" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForwardContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_e157ce62-5e8b-4875-8009-6829de048e7b" xlink:to="loc_us-gaap_ForwardContractsMember_01e492f1-3e3b-43bc-8b2e-99e0335884ee" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/FinancialinstrumentsImpactofChangeinFairValueofNaturalGasDerivativeContractsDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#FinancialinstrumentsImpactofChangeinFairValueofNaturalGasDerivativeContractsDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/FinancialinstrumentsImpactofChangeinFairValueofNaturalGasDerivativeContractsDetail" xlink:type="extended" id="i9cbf596785994ec88e2fc07533a6289e_FinancialinstrumentsImpactofChangeinFairValueofNaturalGasDerivativeContractsDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_22e70121-34b0-452d-be19-419da4f106c0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryAssets_aa8c462a-e011-4695-9833-ff006fad9563" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_22e70121-34b0-452d-be19-419da4f106c0" xlink:to="loc_us-gaap_RegulatoryAssets_aa8c462a-e011-4695-9833-ff006fad9563" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RegulatoryLiabilities_8c6deb6d-5bc6-42cd-85dd-3f84dd939d39" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RegulatoryLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_22e70121-34b0-452d-be19-419da4f106c0" xlink:to="loc_us-gaap_RegulatoryLiabilities_8c6deb6d-5bc6-42cd-85dd-3f84dd939d39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_062c930b-d53a-46a1-90b2-a31ec3c11850" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_22e70121-34b0-452d-be19-419da4f106c0" xlink:to="loc_us-gaap_DerivativeTable_062c930b-d53a-46a1-90b2-a31ec3c11850" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_a60d7b97-57fa-4b0f-9de5-8e90117c7273" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_062c930b-d53a-46a1-90b2-a31ec3c11850" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_a60d7b97-57fa-4b0f-9de5-8e90117c7273" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_a60d7b97-57fa-4b0f-9de5-8e90117c7273_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_a60d7b97-57fa-4b0f-9de5-8e90117c7273" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_a60d7b97-57fa-4b0f-9de5-8e90117c7273_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_39814363-878d-4985-8bf2-82f0b88d0fdd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_a60d7b97-57fa-4b0f-9de5-8e90117c7273" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_39814363-878d-4985-8bf2-82f0b88d0fdd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SwapMember_7bff2705-4e6e-4881-9239-520a15f690bc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_39814363-878d-4985-8bf2-82f0b88d0fdd" xlink:to="loc_us-gaap_SwapMember_7bff2705-4e6e-4881-9239-520a15f690bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CallOptionMember_6f5b9008-a8c3-4c60-90e0-b8f363341744" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CallOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_39814363-878d-4985-8bf2-82f0b88d0fdd" xlink:to="loc_us-gaap_CallOptionMember_6f5b9008-a8c3-4c60-90e0-b8f363341744" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForwardContractsMember_cb1b219c-3793-4cb7-aac4-cb93827f7e31" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ForwardContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_39814363-878d-4985-8bf2-82f0b88d0fdd" xlink:to="loc_us-gaap_ForwardContractsMember_cb1b219c-3793-4cb7-aac4-cb93827f7e31" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/FinancialinstrumentsLongtermEnergyDerivativeContractsDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#FinancialinstrumentsLongtermEnergyDerivativeContractsDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/FinancialinstrumentsLongtermEnergyDerivativeContractsDetail" xlink:type="extended" id="i39b17900bf5d43638de6f215815dff92_FinancialinstrumentsLongtermEnergyDerivativeContractsDetail">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_49a7b235-da5d-4825-8676-a8618689c93d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmount_349f6f22-021a-4903-910e-4cf106872c51" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeNonmonetaryNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_49a7b235-da5d-4825-8676-a8618689c93d" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmount_349f6f22-021a-4903-910e-4cf106872c51" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAveragePriceRiskOptionStrikePrice_9f84f497-e244-43f6-90d9-02d259f2efe3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeAveragePriceRiskOptionStrikePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_49a7b235-da5d-4825-8676-a8618689c93d" xlink:to="loc_us-gaap_DerivativeAveragePriceRiskOptionStrikePrice_9f84f497-e244-43f6-90d9-02d259f2efe3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_0c3cea69-9648-40ab-a401-86aeb8a6065e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_49a7b235-da5d-4825-8676-a8618689c93d" xlink:to="loc_us-gaap_DerivativeTable_0c3cea69-9648-40ab-a401-86aeb8a6065e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_1a1e3454-f3cc-4901-8374-a413e903bc40" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_0c3cea69-9648-40ab-a401-86aeb8a6065e" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_1a1e3454-f3cc-4901-8374-a413e903bc40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_1a1e3454-f3cc-4901-8374-a413e903bc40_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_1a1e3454-f3cc-4901-8374-a413e903bc40" xlink:to="loc_us-gaap_HedgingRelationshipDomain_1a1e3454-f3cc-4901-8374-a413e903bc40_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_7acf1814-b48c-4346-a544-4d100b4ded2e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_1a1e3454-f3cc-4901-8374-a413e903bc40" xlink:to="loc_us-gaap_HedgingRelationshipDomain_7acf1814-b48c-4346-a544-4d100b4ded2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_afbdee86-432a-4c22-a439-651e0949d8ea" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_7acf1814-b48c-4346-a544-4d100b4ded2e" xlink:to="loc_us-gaap_CashFlowHedgingMember_afbdee86-432a-4c22-a439-651e0949d8ea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerAxis_761edb81-992c-4d7c-918a-38f6d6a88654" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermContractForPurchaseOfElectricPowerAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_0c3cea69-9648-40ab-a401-86aeb8a6065e" xlink:to="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerAxis_761edb81-992c-4d7c-918a-38f6d6a88654" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerDomain_761edb81-992c-4d7c-918a-38f6d6a88654_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermContractForPurchaseOfElectricPowerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerAxis_761edb81-992c-4d7c-918a-38f6d6a88654" xlink:to="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerDomain_761edb81-992c-4d7c-918a-38f6d6a88654_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerDomain_7957fbfe-0768-42f6-8a93-1cf8cedf6be3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongTermContractForPurchaseOfElectricPowerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerAxis_761edb81-992c-4d7c-918a-38f6d6a88654" xlink:to="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerDomain_7957fbfe-0768-42f6-8a93-1cf8cedf6be3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NIHUBExpiryDecember2031Member_6d67a574-0993-4683-8fa5-837ccaa4f74c" xlink:href="aqunf-20210630.xsd#aqunf_NIHUBExpiryDecember2031Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerDomain_7957fbfe-0768-42f6-8a93-1cf8cedf6be3" xlink:to="loc_aqunf_NIHUBExpiryDecember2031Member_6d67a574-0993-4683-8fa5-837ccaa4f74c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_IllinoisHubExpirySeptember2030Member_87f1bdc0-f1a1-487d-9604-4b29a479f78d" xlink:href="aqunf-20210630.xsd#aqunf_IllinoisHubExpirySeptember2030Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerDomain_7957fbfe-0768-42f6-8a93-1cf8cedf6be3" xlink:to="loc_aqunf_IllinoisHubExpirySeptember2030Member_87f1bdc0-f1a1-487d-9604-4b29a479f78d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_PJMWesternHUBExpiryDecember2027Member_dcffadb6-99f0-4e45-9350-6ce0f2507e54" xlink:href="aqunf-20210630.xsd#aqunf_PJMWesternHUBExpiryDecember2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerDomain_7957fbfe-0768-42f6-8a93-1cf8cedf6be3" xlink:to="loc_aqunf_PJMWesternHUBExpiryDecember2027Member_dcffadb6-99f0-4e45-9350-6ce0f2507e54" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_NIHUBExpiryDecember2027Member_7ada7e5a-09cd-4a22-acc6-54ebc5173aae" xlink:href="aqunf-20210630.xsd#aqunf_NIHUBExpiryDecember2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerDomain_7957fbfe-0768-42f6-8a93-1cf8cedf6be3" xlink:to="loc_aqunf_NIHUBExpiryDecember2027Member_7ada7e5a-09cd-4a22-acc6-54ebc5173aae" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_ERCOTNorthHUBExpiryDecember2027Member_dc16fcd7-0325-43a3-a62b-add12d0939cc" xlink:href="aqunf-20210630.xsd#aqunf_ERCOTNorthHUBExpiryDecember2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermContractForPurchaseOfElectricPowerDomain_7957fbfe-0768-42f6-8a93-1cf8cedf6be3" xlink:to="loc_aqunf_ERCOTNorthHUBExpiryDecember2027Member_dc16fcd7-0325-43a3-a62b-add12d0939cc" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.algonquinpower.com/role/FinancialinstrumentsEffectsonStatementofOperationsofDerivativeFinancialInstrumentsNotDesignatedasHedgesDetail" xlink:type="simple" xlink:href="aqunf-20210630.xsd#FinancialinstrumentsEffectsonStatementofOperationsofDerivativeFinancialInstrumentsNotDesignatedasHedgesDetail"/>
  <link:definitionLink xlink:role="http://www.algonquinpower.com/role/FinancialinstrumentsEffectsonStatementofOperationsofDerivativeFinancialInstrumentsNotDesignatedasHedgesDetail" xlink:type="extended" id="ifa9580c50ff142cea44c2ab88fb057b6_FinancialinstrumentsEffectsonStatementofOperationsofDerivativeFinancialInstrumentsNotDesignatedasHedgesDetail">
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_3b10f1ae-e18b-49b3-a352-eab2ff528a14" xlink:href="aqunf-20210630.xsd#aqunf_FairValueOfFinancialInstrumentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnDerivatives_24d85ce0-aa18-44f2-96e1-9b62c72d86cf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnrealizedGainLossOnDerivatives"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_3b10f1ae-e18b-49b3-a352-eab2ff528a14" xlink:to="loc_us-gaap_UnrealizedGainLossOnDerivatives_24d85ce0-aa18-44f2-96e1-9b62c72d86cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_c6eb8786-f857-4188-99c7-bf23d791e23a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_3b10f1ae-e18b-49b3-a352-eab2ff528a14" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet_c6eb8786-f857-4188-99c7-bf23d791e23a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNet_b46431a9-00b3-4c62-a53e-c46a3c577157" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeGainLossOnDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_3b10f1ae-e18b-49b3-a352-eab2ff528a14" xlink:to="loc_us-gaap_DerivativeGainLossOnDerivativeNet_b46431a9-00b3-4c62-a53e-c46a3c577157" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_DerivativeInstrumentsGainLossFrozenduetoHedgeDesignation_d8c7e94a-1c05-43df-adea-a7fed4ec59bd" xlink:href="aqunf-20210630.xsd#aqunf_DerivativeInstrumentsGainLossFrozenduetoHedgeDesignation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_3b10f1ae-e18b-49b3-a352-eab2ff528a14" xlink:to="loc_aqunf_DerivativeInstrumentsGainLossFrozenduetoHedgeDesignation_d8c7e94a-1c05-43df-adea-a7fed4ec59bd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDerivativeInstrumentsNetPretax_9dc98679-e37e-4602-b9c0-adaf557a56c8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainLossOnDerivativeInstrumentsNetPretax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_3b10f1ae-e18b-49b3-a352-eab2ff528a14" xlink:to="loc_us-gaap_GainLossOnDerivativeInstrumentsNetPretax_9dc98679-e37e-4602-b9c0-adaf557a56c8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnOilAndGasHedgingActivity_4a4c5031-3f22-416d-87f9-ea5d7a25c70f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GainLossOnOilAndGasHedgingActivity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_3b10f1ae-e18b-49b3-a352-eab2ff528a14" xlink:to="loc_us-gaap_GainLossOnOilAndGasHedgingActivity_4a4c5031-3f22-416d-87f9-ea5d7a25c70f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_aqunf_FairValueOfFinancialInstrumentsTable_ee0cecaa-2aeb-49f9-9620-bdf599a7d3b5" xlink:href="aqunf-20210630.xsd#aqunf_FairValueOfFinancialInstrumentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsLineItems_3b10f1ae-e18b-49b3-a352-eab2ff528a14" xlink:to="loc_aqunf_FairValueOfFinancialInstrumentsTable_ee0cecaa-2aeb-49f9-9620-bdf599a7d3b5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_4527ff08-94e7-471b-a11a-5feb4334c595" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_ee0cecaa-2aeb-49f9-9620-bdf599a7d3b5" xlink:to="loc_us-gaap_HedgingDesignationAxis_4527ff08-94e7-471b-a11a-5feb4334c595" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_4527ff08-94e7-471b-a11a-5feb4334c595_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_4527ff08-94e7-471b-a11a-5feb4334c595" xlink:to="loc_us-gaap_HedgingDesignationDomain_4527ff08-94e7-471b-a11a-5feb4334c595_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_60367256-1634-493a-9614-469e80a142f0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_4527ff08-94e7-471b-a11a-5feb4334c595" xlink:to="loc_us-gaap_HedgingDesignationDomain_60367256-1634-493a-9614-469e80a142f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_e7c84dfd-4a7d-43ef-a30f-21ad3dad5d70" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_60367256-1634-493a-9614-469e80a142f0" xlink:to="loc_us-gaap_NondesignatedMember_e7c84dfd-4a7d-43ef-a30f-21ad3dad5d70" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_8abb5acf-1979-4df1-875f-07c0d73b185e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_60367256-1634-493a-9614-469e80a142f0" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_8abb5acf-1979-4df1-875f-07c0d73b185e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_44740c80-ff6d-4dba-8c1c-cd084d61c3e7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_aqunf_FairValueOfFinancialInstrumentsTable_ee0cecaa-2aeb-49f9-9620-bdf599a7d3b5" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_44740c80-ff6d-4dba-8c1c-cd084d61c3e7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_44740c80-ff6d-4dba-8c1c-cd084d61c3e7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_44740c80-ff6d-4dba-8c1c-cd084d61c3e7" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_44740c80-ff6d-4dba-8c1c-cd084d61c3e7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_bc18eb85-d55a-41b0-be99-118caceba321" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_44740c80-ff6d-4dba-8c1c-cd084d61c3e7" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_bc18eb85-d55a-41b0-be99-118caceba321" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnergyRelatedDerivativeMember_a0b06aca-8aba-4f6f-85ce-0b59fa98d598" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EnergyRelatedDerivativeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_bc18eb85-d55a-41b0-be99-118caceba321" xlink:to="loc_us-gaap_EnergyRelatedDerivativeMember_a0b06aca-8aba-4f6f-85ce-0b59fa98d598" xlink:type="arc" order="0"/>
  </link:definitionLink>
</link:linkbase>
