The 2021 season was the 107th season in the existence of Clube Atlético Mineiro and the 15th consecutive season in the top flight of Brazilian football. In addition to the national league, Atlético Mineiro participated in the Campeonato Mineiro, the Copa do Brasil and the Copa Libertadores. The season was regarded as one of the most successful in the club's history, with the conquests of their second Campeonato Brasileiro, second Copa do Brasil and 46th Campeonato Mineiro titles, claiming them their first domestic treble.