content: <?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
    <headerData>
      <submissionType>144</submissionType>
      <filerInfo>
        <filer>
          <filerCredentials>
            <cik>0001638426</cik>
            <ccc>XXXXXXXX</ccc>
          </filerCredentials>
        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
  
      </filerInfo>
    </headerData>
    <formData>
      <issuerInfo>
        <issuerCik>0001111711</issuerCik>
        <issuerName>NISOURCE INC.</issuerName>
        <secFileNumber>001-16189</secFileNumber>
        <issuerAddress>
          <com:street1>801 EAST 86TH AVE</com:street1>
          <com:city>MERRILLVILLE</com:city>
          <com:stateOrCountry>IN</com:stateOrCountry>
          <com:zipCode>46410-6272</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>2196475200</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Brown Donald Eugene</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Former Officer</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>Fidelity Brokerage Services LLC</name>
          <address>
            <com:street1>900 Salem Street</com:street1>
            <com:city>Smithfield</com:city>
            <com:stateOrCountry>RI</com:stateOrCountry>
            <com:zipCode>02917</com:zipCode>
          </address>
        </brokerOrMarketmakerDetails>
        <noOfUnitsSold>65892</noOfUnitsSold>
        <aggregateMarketValue>1927100.26</aggregateMarketValue>
        <noOfUnitsOutstanding>448305338</noOfUnitsOutstanding>
        <approxSaleDate>05/16/2024</approxSaleDate>
        <securitiesExchangeName>NYSE</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>02/28/2020</acquiredDate>
        <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>26138</amountOfSecuritiesAcquired>
        <paymentDate>02/28/2020</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>02/28/2022</acquiredDate>
        <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>17985</amountOfSecuritiesAcquired>
        <paymentDate>02/28/2022</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>02/28/2023</acquiredDate>
        <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>21769</amountOfSecuritiesAcquired>
        <paymentDate>02/28/2023</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <securitiesSoldInPast3Months>
        <sellerDetails>
          <name>Donald E. Brown</name>
          <address>
            <com:street1>801 East 86th Avenue</com:street1>
            <com:city>Merrillville</com:city>
            <com:stateOrCountry>IN</com:stateOrCountry>
            <com:zipCode>46410</com:zipCode>
          </address>
        </sellerDetails>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <saleDate>03/06/2024</saleDate>
        <amountOfSecuritiesSold>37490</amountOfSecuritiesSold>
        <grossProceeds>1003964.70</grossProceeds>
      </securitiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>05/16/2024</noticeDate>
        <signature>/s/ Jared Cook, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Donald E. Brown</signature>
      </noticeSignature>
    </formData>
  </edgarSubmission>
metadata_documents: [{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 4512}]
text: 144
  0001638426
  XXXXXXXX
  LIVE
  0001111711
  NISOURCE INC.
  001-16189
  801 EAST 86TH AVE
  MERRILLVILLE
  IN
  46410-6272
  2196475200
  Brown Donald Eugene
  Former Officer
  Common
  Fidelity Brokerage Services LLC
  900 Salem Street
  Smithfield
  RI
  02917
  65892
  1927100.26
  448305338
  05/16/2024
  NYSE
  Common
  02/28/2020
  Restricted Stock Vesting
  Issuer
  N
  26138
  02/28/2020
  Compensation
  Common
  02/28/2022
  Restricted Stock Vesting
  Issuer
  N
  17985
  02/28/2022
  Compensation
  Common
  02/28/2023
  Restricted Stock Vesting
  Issuer
  N
  21769
  02/28/2023
  Compensation
  N
  Donald E. Brown
  801 East 86th Avenue
  Merrillville
  IN
  46410
  Common
  03/06/2024
  37490
  1003964.70
  05/16/2024
  /s/ Jared Cook, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Donald E. Brown