<?xml version="1.0" encoding="US-ASCII"?>
<!-- Generated by CompSci Transform (tm) - http://www.compsciresources.com -->
<!-- Created: Mon Mar 30 10:30:47 UTC 2026 -->
<xs:schema elementFormDefault="qualified" targetNamespace="http://nisource.com/20260511" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:us-types="http://xbrl.us/us-types/2009-01-31" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:ni="http://nisource.com/20260511" xmlns:dtr="http://www.xbrl.org/dtr/type/2024-01-31" xmlns:xbrli="http://www.xbrl.org/2003/instance">
  <xs:annotation>
    <xs:appinfo>
      <link:linkbaseRef xlink:type="simple" xlink:href="ni-20260511_lab.xml" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef"/>
      <link:linkbaseRef xlink:type="simple" xlink:href="ni-20260511_pre.xml" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef"/>
      <link:linkbaseRef xlink:type="simple" xlink:href="ni-20260511_def.xml" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef"/>
      <link:roleType roleURI="http://nisource.com/role/AdditionalDimensions" id="ni_r_AdditionalDimensions">
        <link:definition>999000 - Disclosure - Pay vs Performance Disclosure - Additional Dimensions</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
      </link:roleType>
    </xs:appinfo>
  </xs:annotation>
  <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://xbrl.sec.gov/ecd/2025" schemaLocation="https://xbrl.sec.gov/ecd/2025/ecd-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://www.xbrl.org/2009/role/negated" schemaLocation="http://www.xbrl.org/lrr/role/negated-2009-12-16.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/ecd-sub/2025" schemaLocation="https://xbrl.sec.gov/ecd/2025/ecd-sub-2025.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/dei-sub/2025" schemaLocation="https://xbrl.sec.gov/dei/2025/dei-sub-2025.xsd"/>
  <xs:import namespace="http://xbrl.org/2005/xbrldt" schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd"/>
  <xs:element name="JosephHamrockMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="ni_JosephHamrockMember"/>
  <xs:element name="LloydYatesMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="ni_LloydYatesMember"/>
  <xs:element name="PEOAndNonPEONEOMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="ni_PEOAndNonPEONEOMember"/>
  <xs:element name="PensionPlanPriorServiceCostMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="ni_PensionPlanPriorServiceCostMember"/>
  <xs:element name="PensionPlanServiceCostMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="ni_PensionPlanServiceCostMember"/>
  <xs:element name="PensionPlanTotalAveragePensionBenefitAdjustmentMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="ni_PensionPlanTotalAveragePensionBenefitAdjustmentMember"/>
  <xs:element name="PensionRestorationPlanPriorServiceCostMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="ni_PensionRestorationPlanPriorServiceCostMember"/>
  <xs:element name="PensionRestorationPlanServiceCostMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="ni_PensionRestorationPlanServiceCostMember"/>
<!-- [WMV6][fqoT3vLkLjSgmfDQAWGSiuMjL+nmrWbZrYOTzJHkhnXd2Ai5aly7fDOSpI9rrvFVT6T2uOxbysPagMSiZYdG1L6NdJLJMbkfgJsNUMHUetgaGSK+U4Nxr27BwZ5+Cc7v5dfqrOI/KRC/CfoQJNjs01XZgF9HHqC8iI6/BHK8BHEPgmdVyeTnF8YIz7HPzz1cwSJ79sMRTPdPW5FnjAsSjiohRkB1M4ME9uDi08OngpkPn5DRe4Wux+2iVT75qDZ1/r6Qi4HzK7oG659Sr5u//t0gFRnXsd0xt2sEcI7o7rGWiCatxlxYkSk+wzMZLI7UYhKRqOc1wwoVRRD/spAkw4yIpLHZpJSAwH0lVJdBwjPAMrEFUg==] CSR-->
  <xs:element name="PensionRestorationPlanTotalAveragePensionBenefitAdjustmentMember" type="dtr:domainItemType" abstract="true" xbrli:periodType="duration" nillable="true" substitutionGroup="xbrli:item" id="ni_PensionRestorationPlanTotalAveragePensionBenefitAdjustmentMember"/>
</xs:schema>
