In addition to the domestic league, Alavés participated in this season's edition of the Copa del Rey. 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.
The 2020–21 Club Deportivo Tenerife season was the club's 109th season in existence and its eighth consecutive season in the second division of Spanish football.
The 2020–21 UD Almería season was the club's 31st season in existence and the club's sixth consecutive season in the second division of Spanish football.