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>0001188735</cik>
            <ccc>XXXXXXXX</ccc>
          </filerCredentials>
        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
  
      </filerInfo>
    </headerData>
    <formData>
      <issuerInfo>
        <issuerCik>0000029989</issuerCik>
        <issuerName>OMNICOM GROUP INC.</issuerName>
        <secFileNumber>001-10551</secFileNumber>
        <issuerAddress>
          <com:street1>280 PARK AVENUE</com:street1>
          <com:city>NEW YORK</com:city>
          <com:stateOrCountry>NY</com:stateOrCountry>
          <com:zipCode>10017</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>2124153600</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>RICE LINDA JOHNSON</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Director</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>SPS144filing@fmr.com</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>587</noOfUnitsSold>
        <aggregateMarketValue>46199.84</aggregateMarketValue>
        <noOfUnitsOutstanding>197934170</noOfUnitsOutstanding>
        <approxSaleDate>11/15/2023</approxSaleDate>
        <securitiesExchangeName>NYSE</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>10/01/2023</acquiredDate>
        <natureOfAcquisitionTransaction>Compensation</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>587</amountOfSecuritiesAcquired>
        <paymentDate>10/01/2023</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <securitiesSoldInPast3Months>
        <sellerDetails>
          <name>Linda Johnson Rice</name>
          <address>
            <com:street1>280 Park Avenue</com:street1>
            <com:city>New York</com:city>
            <com:stateOrCountry>NY</com:stateOrCountry>
            <com:zipCode>10017</com:zipCode>
          </address>
        </sellerDetails>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <saleDate>08/16/2023</saleDate>
        <amountOfSecuritiesSold>467</amountOfSecuritiesSold>
        <grossProceeds>37472.08</grossProceeds>
      </securitiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>11/15/2023</noticeDate>
        <signature>/s/ Ryan Riviere, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Linda Johnson Rice</signature>
      </noticeSignature>
    </formData>
  </edgarSubmission>
metadata_documents: [{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 3387}]
text: 144
  0001188735
  XXXXXXXX
  LIVE
  0000029989
  OMNICOM GROUP INC.
  001-10551
  280 PARK AVENUE
  NEW YORK
  NY
  10017
  2124153600
  RICE LINDA JOHNSON
  Director
  Common
  SPS144filing@fmr.com
  900 Salem Street
  Smithfield
  RI
  02917
  587
  46199.84
  197934170
  11/15/2023
  NYSE
  Common
  10/01/2023
  Compensation
  Issuer
  N
  587
  10/01/2023
  Compensation
  N
  Linda Johnson Rice
  280 Park Avenue
  New York
  NY
  10017
  Common
  08/16/2023
  467
  37472.08
  11/15/2023
  /s/ Ryan Riviere, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Linda Johnson Rice