2020–21 CD Castellón season

The 2020–21 Club Deportivo Castellón season was the club's 99th season in existence and the club's first season back in the second division of Spanish football, the Segunda División. In addition to the domestic league, Castellón participated in this season's edition of the Copa del Rey. The season covered the period from 26 July 2020 to 30 June 2021.

Matches
The league fixtures were announced on 31 August 2020.