The 2021 All-Ireland Under-20 Football Championship was the fourth staging of the All-Ireland Under-20 Championship and the 58th staging overall of a Gaelic football championship for players between the minor and senior grades. The championship began on 1 July and ended on 15 August 2021. Galway entered the championship as the defending champions, however, they were beaten by Mayo after a penalty shootout in the Connacht semi-final.