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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2025 Workiva-->
<!--r:e6a3fe8f-aa36-43fe-b328-3822c9881e25,g:f813af50-09e5-4488-864e-2d47fdba54d8-->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:aon="http://www.aon.com/20250630" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2024-01-31" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://www.aon.com/20250630">
  <xs:import namespace="http://fasb.org/srt/2025" schemaLocation="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd"/>
  <xs:import namespace="http://fasb.org/us-gaap/2025" schemaLocation="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/dtr/type/2024-01-31" schemaLocation="https://www.xbrl.org/dtr/type/2024-01-31/types.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/country/2025" schemaLocation="https://xbrl.sec.gov/country/2025/country-2025.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/dei/2025" schemaLocation="https://xbrl.sec.gov/dei/2025/dei-2025.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/ecd/2025" schemaLocation="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd"/>
  <xs:annotation>
    <xs:appinfo>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="aon-20250630_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="aon-20250630_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="aon-20250630_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="aon-20250630_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:type="simple"/>
      <link:roleType id="Cover" roleURI="http://www.aon.com/role/Cover">
        <link:definition>0000001 - Document - Cover</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CondensedConsolidatedStatementsofIncomeUnaudited" roleURI="http://www.aon.com/role/CondensedConsolidatedStatementsofIncomeUnaudited">
        <link:definition>9952151 - Statement - Condensed Consolidated Statements of Income (Unaudited)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited" roleURI="http://www.aon.com/role/CondensedConsolidatedStatementsofComprehensiveIncomeUnaudited">
        <link:definition>9952152 - Statement - Condensed Consolidated Statements of Comprehensive Income (Unaudited)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CondensedConsolidatedStatementsofFinancialPosition" roleURI="http://www.aon.com/role/CondensedConsolidatedStatementsofFinancialPosition">
        <link:definition>9952153 - Statement - Condensed Consolidated Statements of Financial Position</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CondensedConsolidatedStatementsofFinancialPositionParenthetical" roleURI="http://www.aon.com/role/CondensedConsolidatedStatementsofFinancialPositionParenthetical">
        <link:definition>9952154 - Statement - Condensed Consolidated Statements of Financial Position (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CondensedConsolidatedStatementsofShareholdersEquityUnaudited" roleURI="http://www.aon.com/role/CondensedConsolidatedStatementsofShareholdersEquityUnaudited">
        <link:definition>9952155 - Statement - Condensed Consolidated Statements of Shareholders&#8217; Equity (Unaudited)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CondensedConsolidatedStatementsofShareholdersEquityUnauditedParenthetical" roleURI="http://www.aon.com/role/CondensedConsolidatedStatementsofShareholdersEquityUnauditedParenthetical">
        <link:definition>9952156 - Statement - Condensed Consolidated Statements of Shareholders&#8217; Equity (Unaudited) (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CondensedConsolidatedStatementsofCashFlowsUnaudited" roleURI="http://www.aon.com/role/CondensedConsolidatedStatementsofCashFlowsUnaudited">
        <link:definition>9952157 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="BasisofPresentation" roleURI="http://www.aon.com/role/BasisofPresentation">
        <link:definition>9952158 - Disclosure - Basis of Presentation</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccountingPrinciplesandPractices" roleURI="http://www.aon.com/role/AccountingPrinciplesandPractices">
        <link:definition>9952159 - Disclosure - Accounting Principles and Practices</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenuefromContractswithCustomers" roleURI="http://www.aon.com/role/RevenuefromContractswithCustomers">
        <link:definition>9952160 - Disclosure - Revenue from Contracts with Customers</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AcceleratingAonUnitedProgram" roleURI="http://www.aon.com/role/AcceleratingAonUnitedProgram">
        <link:definition>9952161 - Disclosure - Accelerating Aon United Program</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CashandCashEquivalentsandShortTermInvestments" roleURI="http://www.aon.com/role/CashandCashEquivalentsandShortTermInvestments">
        <link:definition>9952162 - Disclosure - Cash and Cash Equivalents and Short-Term Investments</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OtherFinancialData" roleURI="http://www.aon.com/role/OtherFinancialData">
        <link:definition>9952163 - Disclosure - Other Financial Data</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AcquisitionsandDispositionsofBusinesses" roleURI="http://www.aon.com/role/AcquisitionsandDispositionsofBusinesses">
        <link:definition>9952164 - Disclosure - Acquisitions and Dispositions of Businesses</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GoodwillandOtherIntangibleAssets" roleURI="http://www.aon.com/role/GoodwillandOtherIntangibleAssets">
        <link:definition>9952165 - Disclosure - Goodwill and Other Intangible Assets</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Debt" roleURI="http://www.aon.com/role/Debt">
        <link:definition>9952166 - Disclosure - Debt</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxes" roleURI="http://www.aon.com/role/IncomeTaxes">
        <link:definition>9952167 - Disclosure - Income Taxes</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ShareholdersEquity" roleURI="http://www.aon.com/role/ShareholdersEquity">
        <link:definition>9952168 - Disclosure - Shareholders' Equity</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="EmployeeBenefits" roleURI="http://www.aon.com/role/EmployeeBenefits">
        <link:definition>9952169 - Disclosure - Employee Benefits</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DerivativesandHedging" roleURI="http://www.aon.com/role/DerivativesandHedging">
        <link:definition>9952170 - Disclosure - Derivatives and Hedging</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsandFinancialInstruments" roleURI="http://www.aon.com/role/FairValueMeasurementsandFinancialInstruments">
        <link:definition>9952171 - Disclosure - Fair Value Measurements and Financial Instruments</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ClaimsLawsuitsandOtherContingencies" roleURI="http://www.aon.com/role/ClaimsLawsuitsandOtherContingencies">
        <link:definition>9952172 - Disclosure - Claims, Lawsuits, and Other Contingencies</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentInformation" roleURI="http://www.aon.com/role/SegmentInformation">
        <link:definition>9952173 - Disclosure - Segment Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccountingPrinciplesandPracticesPolicies" roleURI="http://www.aon.com/role/AccountingPrinciplesandPracticesPolicies">
        <link:definition>9955511 - Disclosure - Accounting Principles and Practices (Policies)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenuefromContractswithCustomersTables" roleURI="http://www.aon.com/role/RevenuefromContractswithCustomersTables">
        <link:definition>9955512 - Disclosure - Revenue from Contracts with Customers (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AcceleratingAonUnitedProgramTables" roleURI="http://www.aon.com/role/AcceleratingAonUnitedProgramTables">
        <link:definition>9955513 - Disclosure - Accelerating Aon United Program (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OtherFinancialDataTables" roleURI="http://www.aon.com/role/OtherFinancialDataTables">
        <link:definition>9955514 - Disclosure - Other Financial Data (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AcquisitionsandDispositionsofBusinessesTables" roleURI="http://www.aon.com/role/AcquisitionsandDispositionsofBusinessesTables">
        <link:definition>9955515 - Disclosure - Acquisitions and Dispositions of Businesses (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GoodwillandOtherIntangibleAssetsTables" roleURI="http://www.aon.com/role/GoodwillandOtherIntangibleAssetsTables">
        <link:definition>9955516 - Disclosure - Goodwill and Other Intangible Assets (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DebtTables" roleURI="http://www.aon.com/role/DebtTables">
        <link:definition>9955517 - Disclosure - Debt (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ShareholdersEquityTables" roleURI="http://www.aon.com/role/ShareholdersEquityTables">
        <link:definition>9955518 - Disclosure - Shareholders' Equity (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="EmployeeBenefitsTables" roleURI="http://www.aon.com/role/EmployeeBenefitsTables">
        <link:definition>9955519 - Disclosure - Employee Benefits (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DerivativesandHedgingTables" roleURI="http://www.aon.com/role/DerivativesandHedgingTables">
        <link:definition>9955520 - Disclosure - Derivatives and Hedging (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsandFinancialInstrumentsTables" roleURI="http://www.aon.com/role/FairValueMeasurementsandFinancialInstrumentsTables">
        <link:definition>9955521 - Disclosure - Fair Value Measurements and Financial Instruments (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentInformationTables" roleURI="http://www.aon.com/role/SegmentInformationTables">
        <link:definition>9955522 - Disclosure - Segment Information (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenuefromContractswithCustomersScheduleofDisaggregationofRevenueDetails" roleURI="http://www.aon.com/role/RevenuefromContractswithCustomersScheduleofDisaggregationofRevenueDetails">
        <link:definition>9955523 - Disclosure - Revenue from Contracts with Customers - Schedule of Disaggregation of Revenue (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenuefromContractswithCustomersScheduleofContractAssetsRollforwardDetails" roleURI="http://www.aon.com/role/RevenuefromContractswithCustomersScheduleofContractAssetsRollforwardDetails">
        <link:definition>9955524 - Disclosure - Revenue from Contracts with Customers - Schedule of Contract Assets Rollforward (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AcceleratingAonUnitedProgramNarrativeDetails" roleURI="http://www.aon.com/role/AcceleratingAonUnitedProgramNarrativeDetails">
        <link:definition>9955525 - Disclosure - Accelerating Aon United Program - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AcceleratingAonUnitedProgramScheduleofProgramCostsIncurredDetails" roleURI="http://www.aon.com/role/AcceleratingAonUnitedProgramScheduleofProgramCostsIncurredDetails">
        <link:definition>9955526 - Disclosure - Accelerating Aon United Program - Schedule of Program Costs Incurred (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AcceleratingAonUnitedProgramScheduleofChangesintheCompanysLiabilitiesfortheProgramDetails" roleURI="http://www.aon.com/role/AcceleratingAonUnitedProgramScheduleofChangesintheCompanysLiabilitiesfortheProgramDetails">
        <link:definition>9955527 - Disclosure - Accelerating Aon United Program - Schedule of Changes in the Company&#8217;s Liabilities for the Program (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CashandCashEquivalentsandShortTermInvestmentsDetails" roleURI="http://www.aon.com/role/CashandCashEquivalentsandShortTermInvestmentsDetails">
        <link:definition>9955528 - Disclosure - Cash and Cash Equivalents and Short-Term Investments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OtherFinancialDataScheduleofOtherIncomeExpenseDetails" roleURI="http://www.aon.com/role/OtherFinancialDataScheduleofOtherIncomeExpenseDetails">
        <link:definition>9955529 - Disclosure - Other Financial Data - Schedule of Other Income (Expense) (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OtherFinancialDataScheduleofAllowanceforDoubtfulAccountsDetails" roleURI="http://www.aon.com/role/OtherFinancialDataScheduleofAllowanceforDoubtfulAccountsDetails">
        <link:definition>9955530 - Disclosure - Other Financial Data - Schedule of Allowance for Doubtful Accounts (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OtherFinancialDataScheduleofOtherCurrentAssetsDetails" roleURI="http://www.aon.com/role/OtherFinancialDataScheduleofOtherCurrentAssetsDetails">
        <link:definition>9955531 - Disclosure - Other Financial Data - Schedule of Other Current Assets (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OtherFinancialDataScheduleofOtherNoncurrentAssetsDetails" roleURI="http://www.aon.com/role/OtherFinancialDataScheduleofOtherNoncurrentAssetsDetails">
        <link:definition>9955532 - Disclosure - Other Financial Data - Schedule of Other Non-current Assets (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OtherFinancialDataScheduleofOtherCurrentLiabilitiesDetails" roleURI="http://www.aon.com/role/OtherFinancialDataScheduleofOtherCurrentLiabilitiesDetails">
        <link:definition>9955533 - Disclosure - Other Financial Data - Schedule of Other Current Liabilities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OtherFinancialDataScheduleofOtherNoncurrentLiabilitiesDetails" roleURI="http://www.aon.com/role/OtherFinancialDataScheduleofOtherNoncurrentLiabilitiesDetails">
        <link:definition>9955534 - Disclosure - Other Financial Data - Schedule of Other Non-current Liabilities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AcquisitionsandDispositionsofBusinessesNarrativeDetails" roleURI="http://www.aon.com/role/AcquisitionsandDispositionsofBusinessesNarrativeDetails">
        <link:definition>9955535 - Disclosure - Acquisitions and Dispositions of Businesses - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AcquisitionsandDispositionsofBusinessesScheduleofConsiderationTransferredandPreliminaryValueofIntangibleAssetsDetails" roleURI="http://www.aon.com/role/AcquisitionsandDispositionsofBusinessesScheduleofConsiderationTransferredandPreliminaryValueofIntangibleAssetsDetails">
        <link:definition>9955536 - Disclosure - Acquisitions and Dispositions of Businesses - Schedule of Consideration Transferred and Preliminary Value of Intangible Assets (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AcquisitionsandDispositionsofBusinessesScheduleofProFormaInformationDetails" roleURI="http://www.aon.com/role/AcquisitionsandDispositionsofBusinessesScheduleofProFormaInformationDetails">
        <link:definition>9955537 - Disclosure - Acquisitions and Dispositions of Businesses - Schedule of Pro Forma Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GoodwillandOtherIntangibleAssetsScheduleofChangesintheNetCarryingAmountofGoodwillDetails" roleURI="http://www.aon.com/role/GoodwillandOtherIntangibleAssetsScheduleofChangesintheNetCarryingAmountofGoodwillDetails">
        <link:definition>9955538 - Disclosure - Goodwill and Other Intangible Assets - Schedule of Changes in the Net Carrying Amount of Goodwill (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GoodwillandOtherIntangibleAssetsScheduleofOtherIntangibleAssetsbyAssetClassDetails" roleURI="http://www.aon.com/role/GoodwillandOtherIntangibleAssetsScheduleofOtherIntangibleAssetsbyAssetClassDetails">
        <link:definition>9955539 - Disclosure - Goodwill and Other Intangible Assets - Schedule of Other Intangible Assets by Asset Class (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GoodwillandOtherIntangibleAssetsScheduleofEstimatedFutureAmortizationExpenseonIntangibleAssetsDetails" roleURI="http://www.aon.com/role/GoodwillandOtherIntangibleAssetsScheduleofEstimatedFutureAmortizationExpenseonIntangibleAssetsDetails">
        <link:definition>9955540 - Disclosure - Goodwill and Other Intangible Assets - Schedule of Estimated Future Amortization Expense on Intangible Assets (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DebtNarrativeDetails" roleURI="http://www.aon.com/role/DebtNarrativeDetails">
        <link:definition>9955541 - Disclosure - Debt - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DebtScheduleofCommercialPaperOutstandingDetails" roleURI="http://www.aon.com/role/DebtScheduleofCommercialPaperOutstandingDetails">
        <link:definition>9955542 - Disclosure - Debt - Schedule of Commercial Paper Outstanding (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesDetails" roleURI="http://www.aon.com/role/IncomeTaxesDetails">
        <link:definition>9955543 - Disclosure - Income Taxes (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ShareholdersEquityNarrativeDetails" roleURI="http://www.aon.com/role/ShareholdersEquityNarrativeDetails">
        <link:definition>9955544 - Disclosure - Shareholders' Equity - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ShareholdersEquityScheduleofShareRepurchasesActivityDetails" roleURI="http://www.aon.com/role/ShareholdersEquityScheduleofShareRepurchasesActivityDetails">
        <link:definition>9955545 - Disclosure - Shareholders' Equity - Schedule of Share Repurchases Activity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ShareholdersEquityScheduleofComponentsofWeightedAverageOrdinarySharesOutstandingDetails" roleURI="http://www.aon.com/role/ShareholdersEquityScheduleofComponentsofWeightedAverageOrdinarySharesOutstandingDetails">
        <link:definition>9955546 - Disclosure - Shareholders' Equity - Schedule of Components of Weighted Average Ordinary Shares Outstanding (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ShareholdersEquityScheduleofComponentsofAccumulatedOtherComprehensiveLossDetails" roleURI="http://www.aon.com/role/ShareholdersEquityScheduleofComponentsofAccumulatedOtherComprehensiveLossDetails">
        <link:definition>9955547 - Disclosure - Shareholders' Equity - Schedule of Components of Accumulated Other Comprehensive Loss (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="EmployeeBenefitsScheduleofComponentsofNetPeriodicBenefitCostDetails" roleURI="http://www.aon.com/role/EmployeeBenefitsScheduleofComponentsofNetPeriodicBenefitCostDetails">
        <link:definition>9955548 - Disclosure - Employee Benefits - Schedule of Components of Net Periodic (Benefit) Cost (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="EmployeeBenefitsNarrativeDetails" roleURI="http://www.aon.com/role/EmployeeBenefitsNarrativeDetails">
        <link:definition>9955549 - Disclosure - Employee Benefits - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="EmployeeBenefitsScheduleofEmployerContributionsDetails" roleURI="http://www.aon.com/role/EmployeeBenefitsScheduleofEmployerContributionsDetails">
        <link:definition>9955550 - Disclosure - Employee Benefits - Schedule of Employer Contributions (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DerivativesandHedgingNarrativeDetails" roleURI="http://www.aon.com/role/DerivativesandHedgingNarrativeDetails">
        <link:definition>9955551 - Disclosure - Derivatives and Hedging - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DerivativesandHedgingScheduleofNotionalandFairValuesofDerivativeInstrumentsDetails" roleURI="http://www.aon.com/role/DerivativesandHedgingScheduleofNotionalandFairValuesofDerivativeInstrumentsDetails">
        <link:definition>9955552 - Disclosure - Derivatives and Hedging - Schedule of Notional and Fair Values of Derivative Instruments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DerivativesandHedgingScheduleofDerivativeGainsLossesRecognizedintheConsolidatedFinancialStatementsDetails" roleURI="http://www.aon.com/role/DerivativesandHedgingScheduleofDerivativeGainsLossesRecognizedintheConsolidatedFinancialStatementsDetails">
        <link:definition>9955553 - Disclosure - Derivatives and Hedging - Schedule of Derivative Gains (Losses) Recognized in the Consolidated Financial Statements (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsandFinancialInstrumentsScheduleofAssetsandLiabilitiesthatareMeasuredatFairValueonaRecurringBasisDetails" roleURI="http://www.aon.com/role/FairValueMeasurementsandFinancialInstrumentsScheduleofAssetsandLiabilitiesthatareMeasuredatFairValueonaRecurringBasisDetails">
        <link:definition>9955554 - Disclosure - Fair Value Measurements and Financial Instruments - Schedule of Assets and Liabilities that are Measured at Fair Value on a Recurring Basis (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsandFinancialInstrumentsScheduleofFinancialInstrumentswheretheCarryingAmountsandFairValuesDifferDetails" roleURI="http://www.aon.com/role/FairValueMeasurementsandFinancialInstrumentsScheduleofFinancialInstrumentswheretheCarryingAmountsandFairValuesDifferDetails">
        <link:definition>9955555 - Disclosure - Fair Value Measurements and Financial Instruments - Schedule of Financial Instruments where the Carrying Amounts and Fair Values Differ (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ClaimsLawsuitsandOtherContingenciesLegalNarrativeDetails" roleURI="http://www.aon.com/role/ClaimsLawsuitsandOtherContingenciesLegalNarrativeDetails">
        <link:definition>9955556 - Disclosure - Claims, Lawsuits, and Other Contingencies - Legal Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ClaimsLawsuitsandOtherContingenciesLettersofCreditNarrativeDetails" roleURI="http://www.aon.com/role/ClaimsLawsuitsandOtherContingenciesLettersofCreditNarrativeDetails">
        <link:definition>9955557 - Disclosure - Claims, Lawsuits, and Other Contingencies - Letters of Credit Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ClaimsLawsuitsandOtherContingenciesPremiumPaymentsNarrativeDetails" roleURI="http://www.aon.com/role/ClaimsLawsuitsandOtherContingenciesPremiumPaymentsNarrativeDetails">
        <link:definition>9955558 - Disclosure - Claims, Lawsuits, and Other Contingencies - Premium Payments Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentInformationNarrativeDetails" roleURI="http://www.aon.com/role/SegmentInformationNarrativeDetails">
        <link:definition>9955559 - Disclosure - Segment Information - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentInformationScheduleofReportableOperatingSegmentsConsolidatedRevenueandSegmentOperatingIncomeDetails" roleURI="http://www.aon.com/role/SegmentInformationScheduleofReportableOperatingSegmentsConsolidatedRevenueandSegmentOperatingIncomeDetails">
        <link:definition>9955560 - Disclosure - Segment Information - Schedule of Reportable Operating Segments, Consolidated Revenue and Segment Operating Income (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xs:appinfo>
  </xs:annotation>
  <xs:element id="aon_GuaranteesOfAonPlcs3.875SeniorNotesDue2025Member" abstract="true" name="GuaranteesOfAonPlcs3.875SeniorNotesDue2025Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonPlcs2.875SeniorNotesDue2026Member" abstract="true" name="GuaranteesOfAonPlcs2.875SeniorNotesDue2026Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonCorporationAndAonGlobalHoldingsPlcs285SeniorNotesDue2027Member" abstract="true" name="GuaranteesOfAonCorporationAndAonGlobalHoldingsPlcs285SeniorNotesDue2027Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonNorthAmericaInc.s5.125SeniorNotesDue2027Member" abstract="true" name="GuaranteesOfAonNorthAmericaInc.s5.125SeniorNotesDue2027Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonNorthAmericaInc.s5.150SeniorNotesDue2029Member" abstract="true" name="GuaranteesOfAonNorthAmericaInc.s5.150SeniorNotesDue2029Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonPlcs205SeniorNotesDue2031Member" abstract="true" name="GuaranteesOfAonPlcs205SeniorNotesDue2031Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonPlcs260SeniorNotesDue2031Member" abstract="true" name="GuaranteesOfAonPlcs260SeniorNotesDue2031Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonNorthAmericaInc.s5.300SeniorNotesDue2031Member" abstract="true" name="GuaranteesOfAonNorthAmericaInc.s5.300SeniorNotesDue2031Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonPlcs500SeniorNotesDue2032Member" abstract="true" name="GuaranteesOfAonPlcs500SeniorNotesDue2032Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonPlcs535SeniorNotesDue2033Member" abstract="true" name="GuaranteesOfAonPlcs535SeniorNotesDue2033Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonNorthAmericaInc.s5.450SeniorNotesDue2034Member" abstract="true" name="GuaranteesOfAonNorthAmericaInc.s5.450SeniorNotesDue2034Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonPlcs4.250SeniorNotesDue2042Member" abstract="true" name="GuaranteesOfAonPlcs4.250SeniorNotesDue2042Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonPlcs4.450SeniorNotesDue2043Member" abstract="true" name="GuaranteesOfAonPlcs4.450SeniorNotesDue2043Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonPlcs4.600SeniorNotesDue2044Member" abstract="true" name="GuaranteesOfAonPlcs4.600SeniorNotesDue2044Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonPlcs4.750SeniorNotesDue2045Member" abstract="true" name="GuaranteesOfAonPlcs4.750SeniorNotesDue2045Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonPlcs290SeniorNotesDue2051Member" abstract="true" name="GuaranteesOfAonPlcs290SeniorNotesDue2051Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonCorporationAndAonGlobalHoldingsPlcs390SeniorNotesDue2052Member" abstract="true" name="GuaranteesOfAonCorporationAndAonGlobalHoldingsPlcs390SeniorNotesDue2052Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GuaranteesOfAonNorthAmericaInc.s5.750SeniorNotesDue2054Member" abstract="true" name="GuaranteesOfAonNorthAmericaInc.s5.750SeniorNotesDue2054Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_AmortizationAndImpairmentOfIntangibleAssets" abstract="false" name="AmortizationAndImpairmentOfIntangibleAssets" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_OtherGeneralExpenses" abstract="false" name="OtherGeneralExpenses" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_FiduciaryAssets" abstract="false" name="FiduciaryAssets" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_FiduciaryLiabilities" abstract="false" name="FiduciaryLiabilities" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_NoncontrollingInterestDecreaseFromRedemptionsOrPurchaseOfInterestsNetOfInterestAcquired" abstract="false" name="NoncontrollingInterestDecreaseFromRedemptionsOrPurchaseOfInterestsNetOfInterestAcquired" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_PaymentsForProceedsFromMarketableSecurities" abstract="false" name="PaymentsForProceedsFromMarketableSecurities" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_IncreaseInFiduciaryLiabilitiesNetOfFiduciaryReceivables" abstract="false" name="IncreaseInFiduciaryLiabilitiesNetOfFiduciaryReceivables" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_ProceedsFromPaymentsForNoncontrollingInterestsAndOtherFinancingActivities" abstract="false" name="ProceedsFromPaymentsForNoncontrollingInterestsAndOtherFinancingActivities" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_OtherFinancialDataAbstract" abstract="true" name="OtherFinancialDataAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="aon_ScheduleOfCommercialPaperOutstandingTableTextBlock" abstract="false" name="ScheduleOfCommercialPaperOutstandingTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="aon_ScheduleOfEmployerContributionsTableTextBlock" abstract="false" name="ScheduleOfEmployerContributionsTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="aon_CommercialRiskSolutionsMember" abstract="true" name="CommercialRiskSolutionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_ReinsuranceSolutionsMember" abstract="true" name="ReinsuranceSolutionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_HealthSolutionsMember" abstract="true" name="HealthSolutionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_WealthSolutionsMember" abstract="true" name="WealthSolutionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_CorporateAndEliminationsMember" abstract="true" name="CorporateAndEliminationsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_AmericasOtherThanUnitedStatesMember" abstract="true" name="AmericasOtherThanUnitedStatesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_EuropeMiddleEastAndAfricaOtherThanUnitedKingdomAndIrelandMember" abstract="true" name="EuropeMiddleEastAndAfricaOtherThanUnitedKingdomAndIrelandMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_RiskCapitalSegmentMember" abstract="true" name="RiskCapitalSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_HumanCapitalSegmentMember" abstract="true" name="HumanCapitalSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_CapitalizedCostToFulfillCustomerContractsMember" abstract="true" name="CapitalizedCostToFulfillCustomerContractsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_CapitalizedCostToObtainCustomerContractsMember" abstract="true" name="CapitalizedCostToObtainCustomerContractsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_ChangeInCapitalizedContractCostsRollForward" abstract="true" name="ChangeInCapitalizedContractCostsRollForward" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="aon_CapitalizedContractCostAdditions" abstract="false" name="CapitalizedContractCostAdditions" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_CapitalizedContractCostForeignCurrencyAndOtherAdjustmentsNet" abstract="false" name="CapitalizedContractCostForeignCurrencyAndOtherAdjustmentsNet" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_AcceleratingAonUnitedProgramMember" abstract="true" name="AcceleratingAonUnitedProgramMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_RestructuringAndRelatedCostPeriod" abstract="false" name="RestructuringAndRelatedCostPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="aon_RestructuringAndRelatedCostExpectedCostCashCharges" abstract="false" name="RestructuringAndRelatedCostExpectedCostCashCharges" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_RestructuringAndRelatedCostExpectedCostNonCashCharges" abstract="false" name="RestructuringAndRelatedCostExpectedCostNonCashCharges" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_TechnologyAndOtherMember" abstract="true" name="TechnologyAndOtherMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_WorkforceOptimizationMember" abstract="true" name="WorkforceOptimizationMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_AssetImpairmentsMember" abstract="true" name="AssetImpairmentsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_CashAndCashEquivalentsAndShortTermInvestments" abstract="false" name="CashAndCashEquivalentsAndShortTermInvestments" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_ShortTermInvestmentsOperatingFundsRequiredToBeHeld" abstract="false" name="ShortTermInvestmentsOperatingFundsRequiredToBeHeld" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_GainLossOnFinancialInstrumentsAndOther" abstract="false" name="GainLossOnFinancialInstrumentsAndOther" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_DeferredConsiderationOnDivestiture" abstract="false" name="DeferredConsiderationOnDivestiture" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_MovementOfAccountsReceivableAllowanceForCreditLossCurrentRollForward" abstract="true" name="MovementOfAccountsReceivableAllowanceForCreditLossCurrentRollForward" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="aon_AccountsReceivableAllowanceForCreditLossWriteOffNetOfRecoveries" abstract="false" name="AccountsReceivableAllowanceForCreditLossWriteOffNetOfRecoveries" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_AccountsReceivableAllowanceForCreditLossForeignCurrencyTranslationAndOther" abstract="false" name="AccountsReceivableAllowanceForCreditLossForeignCurrencyTranslationAndOther" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_PaymentsToAcquireBusinessesEscrowDeposits" abstract="false" name="PaymentsToAcquireBusinessesEscrowDeposits" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_OperatingLeaseAndFinanceLeaseLiabilityCurrent" abstract="false" name="OperatingLeaseAndFinanceLeaseLiabilityCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_ContractWithCustomerLiabilityIncludingNewContractRevenueRecognized" abstract="false" name="ContractWithCustomerLiabilityIncludingNewContractRevenueRecognized" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_EmployeeRelatedLiabilitiesNoncurrent" abstract="false" name="EmployeeRelatedLiabilitiesNoncurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_GriffithsArmourMember" abstract="true" name="GriffithsArmourMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_NFPIntermediateHoldingsACorp.Member" abstract="true" name="NFPIntermediateHoldingsACorp.Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_May12017DivestedBusinessMember" abstract="true" name="May12017DivestedBusinessMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCashAndCertainLiabilities" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCashAndCertainLiabilities" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentNotesReceivable" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentNotesReceivable" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredTaxLiabilities" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredTaxLiabilities" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_NumberOfDispositions" abstract="false" name="NumberOfDispositions" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="aon_GainOnDispositionOfBusiness" abstract="false" name="GainOnDispositionOfBusiness" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_DisposalGroupIncludingDiscontinuedOperationDeferredConsideration" abstract="false" name="DisposalGroupIncludingDiscontinuedOperationDeferredConsideration" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_A2025AcquisitionsMember" abstract="true" name="A2025AcquisitionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_CustomerRelatedAndContractBasedMember" abstract="true" name="CustomerRelatedAndContractBasedMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_BusinessCombinationRecognizedAssetAcquiredFiduciaryAssets" abstract="false" name="BusinessCombinationRecognizedAssetAcquiredFiduciaryAssets" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_BusinessCombinationRecognizedAssetAcquiredOperatingLeaseRightOfUseAssets" abstract="false" name="BusinessCombinationRecognizedAssetAcquiredOperatingLeaseRightOfUseAssets" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_BusinessCombinationRecognizedAssetAcquiredAssetsAcquiredIncludingGoodwill" abstract="false" name="BusinessCombinationRecognizedAssetAcquiredAssetsAcquiredIncludingGoodwill" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_BusinessCombinationRecognizedLiabilityAssumedFiduciaryLiabilities" abstract="false" name="BusinessCombinationRecognizedLiabilityAssumedFiduciaryLiabilities" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_BusinessCombinationRecognizedLiabilityAssumedNoncurrentOperatingLeaseLiabilities" abstract="false" name="BusinessCombinationRecognizedLiabilityAssumedNoncurrentOperatingLeaseLiabilities" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_BusinessCombinationRecognizedLiabilityAssumedRedeemableNonControllingInterests" abstract="false" name="BusinessCombinationRecognizedLiabilityAssumedRedeemableNonControllingInterests" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_BusinessCombinationRecognizedLiabilityAssumedNonRedeemableNonControllingInterests" abstract="false" name="BusinessCombinationRecognizedLiabilityAssumedNonRedeemableNonControllingInterests" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_MarketingTechnologyAndOtherMember" abstract="true" name="MarketingTechnologyAndOtherMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_A2.875SeniorNotesDueMay2026Member" abstract="true" name="A2.875SeniorNotesDueMay2026Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_A3.875SeniorNotesDueDecember2025Member" abstract="true" name="A3.875SeniorNotesDueDecember2025Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_A350SeniorNotesDueJune2024Member" abstract="true" name="A350SeniorNotesDueJune2024Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_A6.875SeniorNotesDue2028Member" abstract="true" name="A6.875SeniorNotesDue2028Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_A4.875SeniorSecuredNotesDue2028Member" abstract="true" name="A4.875SeniorSecuredNotesDue2028Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_A7.500SeniorSecuredNotesDue2030Member" abstract="true" name="A7.500SeniorSecuredNotesDue2030Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_A8.500SeniorSecuredNotesDue2031Member" abstract="true" name="A8.500SeniorSecuredNotesDue2031Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_A5.125SeniorNotesDueMarch2027Member" abstract="true" name="A5.125SeniorNotesDueMarch2027Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_A5.150SeniorNotesDueMarch2029Member" abstract="true" name="A5.150SeniorNotesDueMarch2029Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_A5.300SeniorNotesDueMarch2031Member" abstract="true" name="A5.300SeniorNotesDueMarch2031Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_A5.450SeniorNotesDueMarch2034Member" abstract="true" name="A5.450SeniorNotesDueMarch2034Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_A5.750SeniorNotesDueMarch2054Member" abstract="true" name="A5.750SeniorNotesDueMarch2054Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_USCommercialPaperProgramMember" abstract="true" name="USCommercialPaperProgramMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_EuropeanMultiCurrencyCommercialPaperProgramMember" abstract="true" name="EuropeanMultiCurrencyCommercialPaperProgramMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_CreditFacilityExpiringSeptember2027Member" abstract="true" name="CreditFacilityExpiringSeptember2027Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_CreditFacilityExpiringOctober2028Member" abstract="true" name="CreditFacilityExpiringOctober2028Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_NumberOfCreditFacilities" abstract="false" name="NumberOfCreditFacilities" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="aon_ShortTermDebtAverageOutstandingAmountWeightedAverageInterestRate" abstract="false" name="ShortTermDebtAverageOutstandingAmountWeightedAverageInterestRate" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="aon_RepurchaseProgramMember" abstract="true" name="RepurchaseProgramMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_StockRepurchaseProgramAuthorizedAmountIncreaseDuringPeriod" abstract="false" name="StockRepurchaseProgramAuthorizedAmountIncreaseDuringPeriod" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_OtherInternationalPlanMember" abstract="true" name="OtherInternationalPlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_DefinedBenefitPlanNetPeriodicBenefitCostBeforeRecognizedNetGainLossDueToSettlementsAndCurtailments" abstract="false" name="DefinedBenefitPlanNetPeriodicBenefitCostBeforeRecognizedNetGainLossDueToSettlementsAndCurtailments" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_MaximumAverageMaturityOfForeignCurrencyDerivatives" abstract="false" name="MaximumAverageMaturityOfForeignCurrencyDerivatives" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="aon_MoneyMarketFundsAndOtherHighlyLiquidDebtSecuritiesMember" abstract="true" name="MoneyMarketFundsAndOtherHighlyLiquidDebtSecuritiesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_GovernmentBondSecuritiesMember" abstract="true" name="GovernmentBondSecuritiesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_BasisMoneyMarketFundsAndHighlyLiquidSecuritiesFairValueDisclosure" abstract="false" name="BasisMoneyMarketFundsAndHighlyLiquidSecuritiesFairValueDisclosure" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_FatalPlainCrashInNovember2016Member" abstract="true" name="FatalPlainCrashInNovember2016Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="aon_LossContingencyDamagesSoughtValueOptionOne" abstract="false" name="LossContingencyDamagesSoughtValueOptionOne" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_LossContingencyDamagesSoughtValueOptionTwo" abstract="false" name="LossContingencyDamagesSoughtValueOptionTwo" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_LossContingencyDamagesSoughtValueOptionThree" abstract="false" name="LossContingencyDamagesSoughtValueOptionThree" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="aon_LossContingencyNumberOfJurisdictions" abstract="false" name="LossContingencyNumberOfJurisdictions" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="aon_OperatingMarginPercentage" abstract="false" name="OperatingMarginPercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
</xs:schema>
