<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-05-20</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000704051</issuerCik>
        <issuerName>LEGG MASON, INC.</issuerName>
        <issuerTradingSymbol>LM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000928265</rptOwnerCik>
            <rptOwnerName>PELTZ NELSON</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>280 PARK AVE</rptOwnerStreet1>
            <rptOwnerStreet2>41ST FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10017</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001345471</rptOwnerCik>
            <rptOwnerName>TRIAN FUND MANAGEMENT, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>280 PARK AVE</rptOwnerStreet1>
            <rptOwnerStreet2>41ST FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10017</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-05-20</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2457808</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>49.8001</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Please see explanation below</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The price shown in Column 4 is a weighted average sale price. The price range for the sale is $49.775 to $49.8350. The Reporting Persons undertake to provide upon request by the staff of the Securities and Exchange Commission, the Issuer or a security holder of the Issuer, full information regarding the number of shares sold at each separate price.</footnote>
        <footnote id="F2">Trian Fund Management, L.P. (&quot;Trian Management&quot;) serves as the management company for Trian Partners, L.P., Trian Partners Master Fund, L.P., Trian Partners Parallel Fund I, L.P., Trian Partners Strategic Investment Fund-A, L.P., Trian Partners Strategic Investment Fund-N, L.P., Trian Partners Strategic Investment Fund-D, L.P., Trian Partners Fund (Sub)-G, L.P., Trian Partners Strategic Fund-G II, L.P., Trian Partners Strategic Fund G-III, L.P., Trian Partners Strategic Fund-K, L.P., and Trian Partners Strategic Fund-C, Ltd. (collectively, the &quot;Trian Entities&quot;) and as such determines the investment and voting decisions of the Trian Entities with respect to the shares of the Issuer held by them. Mr. Peltz is a member of Trian Fund Management GP, LLC, which is the general partner of Trian Management, and therefore is in a position to determine the investment and voting decisions made by Trian Management on its own behalf and on behalf of the Trian Entities.</footnote>
        <footnote id="F3">(FN 2, contd.) Accordingly, Mr. Peltz, may be deemed to indirectly beneficially own (as that term is defined in Rule 13d-3 under the Securities Exchange Act of 1934) the shares beneficially owned by Trian Management and the Trian Entities and Trian Management may be deemed to indirectly beneficially own (as that term is defined in Rule 13d-3 under the Securities Act of 1934) the shares beneficially owned by the Trian Entities. The Reporting Persons disclaim beneficial ownership of such shares except to the extent of their respective pecuniary interests therein and this report shall not be deemed an admission that the Reporting Persons are the beneficial owner of such securities for purposes of Section 16 or for any other purpose. Mr. Peltz is a director of the Issuer.</footnote>
    </footnotes>

    <remarks>The shares which are reported on this filing as being indirectly held by Nelson Peltz through his relationship with Trian Management and the Trian Entities and by Trian Management through its relationship with the Trian Entities, and the transactions with respect to such shares, are also reported on the filing on Form 4 made by Edward Garden and Trian Management, and represent the same shares and transactions.</remarks>

    <ownerSignature>
        <signatureName>Stuart I. Rosen, Attorney-In-Fact for Nelson Peltz</signatureName>
        <signatureDate>2020-05-22</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Stuart I. Rosen, Attorney-In-Fact for Nelson Peltz, member of the general partner of Trian Fund Management, L.P.</signatureName>
        <signatureDate>2020-05-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
