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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-02-07</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001620280</issuerCik>
        <issuerName>Uniti Group Inc.</issuerName>
        <issuerTradingSymbol>UNIT</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001681489</rptOwnerCik>
            <rptOwnerName>Frey Andrew</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>10802 EXECUTIVE CENTER DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>BENTON BUILDING, SUITE 300</rptOwnerStreet2>
            <rptOwnerCity>LITTLE ROCK</rptOwnerCity>
            <rptOwnerState>AR</rptOwnerState>
            <rptOwnerZipCode>72211</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>2018-02-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>6828</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15885</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Subject to the reporting person's continued service on the issuer's board of directors, these shares will vest on February 7, 2019.</footnote>
        <footnote id="F2">The reporting person holds any stock, stock options, restricted stock or stock units or other rights to purchase or receive stock issued to him as compensation for his services as a director of the issuer as a nominee, and for the benefit, of Searchlight II CLS, L.P. (Searchlight). The reporting person, a partner of Searchlight Capital, L.P., an affiliate of Searchlight, serves as a director of the issuer as a nominee of Searchlight. As a result, Searchlight is deemed to have a pecuniary interest in these shares, and the reporting person hereby disclaims beneficial ownership of all securities, and this report shall not be deemed an admission that he is the beneficial owner of the securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Andrew Frey by Daniel L. Heard, Attorney-In-Fact</signatureName>
        <signatureDate>2018-02-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
