The following is a summary of Louth county football team's 2021 season.
There was no O'Byrne Cup in 2021 due to the impact of the COVID-19 pandemic on Gaelic games.
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Antrim and Louth shared the Division 4 title, as Louth had a championship game on 27 June 2021.
The draw for the preliminary rounds and quarter-finals took place on 20 April 2021.
Due to the impact of the COVID-19 pandemic on Gaelic games, there was no back-door route into the All-Ireland Championship. Therefore, because Louth did not win the Leinster Championship, they did not qualify for the 2021 All-Ireland Championship.