The 2020–21 season was the 122nd season in the existence of Athletic Bilbao and the club's 90th consecutive season in the top flight of Spanish football. In addition to the domestic league, Athletic Bilbao participated in this season's editions of the Copa del Rey and the Supercopa de España. The season covered the period from 20 July 2020 to 30 June 2021, with the late start to the season due to the COVID-19 pandemic in Spain.