The 2021 Cavan Senior Football Championship was the 112th edition of Cavan GAA's premier Gaelic football tournament for senior graded clubs in County Cavan, Ireland. The championship began on 2 September 2021. The tournament consists of 13 teams, with the winner going on to represent Cavan in the Ulster Senior Club Football Championship. Crosserlough entered the championship as the defending champions, but exited the championship at the group stage. The replayed final was the first senior men's county final in the country to be refereed by a woman, by Laragh United's Maggie Farrelly.