2020–21 İstanbul Başakşehir F.K. season

The 2020–21 season was the 31st season in existence of İstanbul Başakşehir and the seventh consecutive season in the top flight of Turkish football, the Süper Lig. In addition to the domestic league, Başakşehir participated in this season's editions of the Turkish Cup, the Turkish Super Cup and the UEFA Champions League. The season covered the period from 5 August 2020 to 30 June 2021.

Results by round
Note: Since the league was expanded to 21 teams each team earned a bye twice this season.

Group stage
The group stage draw was held on 1 October 2020.