The 2019–20 season was 1. FSV Mainz 05's 121st season in existence and the club's 39th consecutive season in the top flight of German football. In addition to the domestic league, 1. FSV Mainz 05 participated in this season's edition of the DFB-Pokal. The season covered a period from 1 July 2019 to 30 June 2020.