The 2021 All-Ireland Senior Football Championship was the 134th edition of the Gaelic Athletic Association's premier inter-county Gaelic football tournament since its establishment in 1887. Thirty one of the thirty two Irish counties took part – Kilkenny did not compete. London and New York were withdrawn as a result of the public health restrictions imposed due to the COVID-19 pandemic. There was no "Super 8" group stage (officially the all-Ireland quarter-final group stage). The four provincial winners advanced to the All-Ireland semi-finals which were played as single knockout games.