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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-06-16</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001041657</issuerCik>
        <issuerName>URBAN ONE, INC.</issuerName>
        <issuerTradingSymbol>UONE/UONEK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001162953</rptOwnerCik>
            <rptOwnerName>ARMSTRONG  D GEOFFREY</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>5900 PRINCESS GARDEN PARKWAY</rptOwnerStreet1>
            <rptOwnerStreet2>7TH FL</rptOwnerStreet2>
            <rptOwnerCity>LANHAM</rptOwnerCity>
            <rptOwnerState>MD</rptOwnerState>
            <rptOwnerZipCode>20706</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class D Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-06-16</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>9124</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>196041</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class D Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-06-17</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>12500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>208541</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents vesting of a grant of restricted stock units pursuant to our director compensation policy; our non-employee directors each receive $50,000 of restricted stock units which vest over a two-year period. The number of shares was determined by dividing the closing price of our Class D common stock on the date of the applicable annual meeting into $50,000.</footnote>
        <footnote id="F2">The total represents all shares held by the reporting person across all classes of Urban One, Inc. stock, Classes A, B, C, and D.  The reporting person beneficially owns a total of 208,541 shares of Urban One, Inc. common stock as follows: (1) 10,000 shares of Class A common stock; and (2) 198,541 shares of Class D common stock.</footnote>
        <footnote id="F3">This total includes options to purchase 30,120 shares of Class D common stock held by Mr. Armstrong, with an exercise price of $0.83 per share.</footnote>
        <footnote id="F4">This total is adjusted from the Form 4 previously filed on May 20, 2021 as the following options included in the total have expired: 22,935 Class D shares with an exercise price of $1.09 per share.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Karen Wishart</signatureName>
        <signatureDate>2021-06-21</signatureDate>
    </ownerSignature>
</ownershipDocument>
