<?xml version="1.0" encoding="US-ASCII"?>
<!-- DFIN New ActiveDisclosure (SM) XBRL Schema Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date :2023-03-15T10:53:15.6331+00:00 -->
<!-- Copyright (c) 2023 Donnelly Financial Solutions, Inc. All Rights Reserved. -->
<xsd:schema targetNamespace="http://www.blackhillscorp.com/20230315" attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2020-01-21" xmlns:enum2="http://xbrl.org/2020/extensible-enumerations-2.0" xmlns:ecd-sub="http://xbrl.sec.gov/ecd-sub/2022q4" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:us-gaap="http://fasb.org/us-gaap/2022" xmlns:dei="http://xbrl.sec.gov/dei/2022" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:bkh="http://www.blackhillscorp.com/20230315" xmlns:xlink="http://www.w3.org/1999/xlink">
  <xsd:import schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" namespace="http://www.xbrl.org/2003/instance"/>
  <xsd:import schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" namespace="http://www.xbrl.org/2003/linkbase"/>
  <xsd:import schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd" namespace="http://xbrl.org/2005/xbrldt"/>
  <xsd:import schemaLocation="https://xbrl.sec.gov/dei/2022/dei-2022.xsd" namespace="http://xbrl.sec.gov/dei/2022"/>
  <xsd:import schemaLocation="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd" namespace="http://fasb.org/us-gaap/2022"/>
  <xsd:import schemaLocation="https://www.xbrl.org/dtr/type/2020-01-21/types.xsd" namespace="http://www.xbrl.org/dtr/type/2020-01-21"/>
  <xsd:import schemaLocation="https://xbrl.sec.gov/ecd/2022q4/ecd-sub-2022q4.xsd" namespace="http://xbrl.sec.gov/ecd-sub/2022q4"/>
  <xsd:annotation>
    <xsd:appinfo>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="bkh-20230315_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:title="Labels link" xlink:type="simple"/>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="bkh-20230315_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:title="Presentation link" xlink:type="simple"/>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="bkh-20230315_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:title="Definition link" xlink:type="simple"/>
      <link:roleType roleURI="http://www.blackhillscorp.com/20230315/taxonomy/role/DocumentDocumentAndEntityInformation" id="DocumentDocumentAndEntityInformation">
        <link:definition>100000 - Document - Document and Entity Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xsd:appinfo>
  </xsd:annotation>
  <xsd:element id="bkh_EarningsPerShareAvailableForCommonStock" name="EarningsPerShareAvailableForCommonStock" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bkh_EarningsPerShareFromOngoingOperationsAsAdjusted" name="EarningsPerShareFromOngoingOperationsAsAdjusted" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bkh_ImpairmentOfInvestment" name="ImpairmentOfInvestment" type="dtr-types:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bkh_NonPeoNeoAverageChangeInFairValueFromLastDayOfPriorYearToLastDayOfYearOfUnvestedEquityAwards" name="NonPeoNeoAverageChangeInFairValueFromLastDayOfPriorYearToLastDayOfYearOfUnvestedEquityAwards" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_NonPeoNeoAverageChangeInFairValueFromLastDayOfPriorYearToVestingDateOfUnvestedEquityAwardsThatVestedDuringYear" name="NonPeoNeoAverageChangeInFairValueFromLastDayOfPriorYearToVestingDateOfUnvestedEquityAwardsThatVestedDuringYear" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_NonPeoNeoAverageExclusionOfChangeInPensionValue" name="NonPeoNeoAverageExclusionOfChangeInPensionValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_NonPeoNeoAverageExclusionOfStockAwardsAndOptionAwards" name="NonPeoNeoAverageExclusionOfStockAwardsAndOptionAwards" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_NonPeoNeoAverageFairValueAtLastDayOfPriorYearOfEquityAwardsForfeitedDuringYear" name="NonPeoNeoAverageFairValueAtLastDayOfPriorYearOfEquityAwardsForfeitedDuringYear" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_NonPeoNeoAverageInclusionOfEquityValues" name="NonPeoNeoAverageInclusionOfEquityValues" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_NonPeoNeoAverageInclusionOfPensionServiceCost" name="NonPeoNeoAverageInclusionOfPensionServiceCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_NonPeoNeoAverageValueOfDividendsOrOtherEarningsPaidOnStockOrOptionAwardsNotOtherwiseIncluded" name="NonPeoNeoAverageValueOfDividendsOrOtherEarningsPaidOnStockOrOptionAwardsNotOtherwiseIncluded" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_NonPeoNeoAverageVestingDateFairValueOfEquityAwardsGrantedDuringYearThatVestedDuringYear" name="NonPeoNeoAverageVestingDateFairValueOfEquityAwardsGrantedDuringYearThatVestedDuringYear" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_NonPeoNeoAverageYearEndFairValueOfEquityAwardsGrantedDuringYearThatRemainedUnvested" name="NonPeoNeoAverageYearEndFairValueOfEquityAwardsGrantedDuringYearThatRemainedUnvested" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_NonPeoNeoTotalAverageInclusionOfEquityValues" name="NonPeoNeoTotalAverageInclusionOfEquityValues" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_PeoChangeInFairValueFromLastDayOfPriorYearToLastDayOfYearOfUnvestedEquityAwards" name="PeoChangeInFairValueFromLastDayOfPriorYearToLastDayOfYearOfUnvestedEquityAwards" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_PeoChangeInFairValueFromLastDayOfPriorYearToVestingDateOfUnvestedEquityAwardsThatVestedDuringYear" name="PeoChangeInFairValueFromLastDayOfPriorYearToVestingDateOfUnvestedEquityAwardsThatVestedDuringYear" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_PeoExclusionOfChangeInPensionValue" name="PeoExclusionOfChangeInPensionValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_PeoExclusionOfStockAwards" name="PeoExclusionOfStockAwards" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_PeoFairValueAtLastDayOfPriorYearOfEquityAwardsForfeitedDuringYear" name="PeoFairValueAtLastDayOfPriorYearOfEquityAwardsForfeitedDuringYear" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_PeoInclusionOfEquityValues" name="PeoInclusionOfEquityValues" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_PeoInclusionOfPensionServiceCost" name="PeoInclusionOfPensionServiceCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bkh_PeoTotalInclusionOfEquityValues" name="PeoTotalInclusionOfEquityValues" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_PeoValueOfDividendsOrOtherEarningsPaidOnStockOrOptionAwardsNotOtherwiseIncluded" name="PeoValueOfDividendsOrOtherEarningsPaidOnStockOrOptionAwardsNotOtherwiseIncluded" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_PeoVestingDateFairValueOfEquityAwardsGrantedDuringYearThatVestedDuringYear" name="PeoVestingDateFairValueOfEquityAwardsGrantedDuringYearThatVestedDuringYear" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_PeoYearEndFairValueOfEquityAwardsGrantedDuringYearThatRemainedUnvested" name="PeoYearEndFairValueOfEquityAwardsGrantedDuringYearThatRemainedUnvested" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bkh_BrianGIversonMember" name="BrianGIversonMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bkh_ErikDKellerMember" name="ErikDKellerMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bkh_JenniferCLandisMember" name="JenniferCLandisMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bkh_RichardWKinzleyMember" name="RichardWKinzleyMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bkh_ScottABuchholzMember" name="ScottABuchholzMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bkh_StuartAWevikMember" name="StuartAWevikMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
</xsd:schema>
