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.
Note: The Paris Saint-Germain v İstanbul Başakşehir match was suspended after 14 minutes, with the score 0–0 at the time, as both teams left the pitch in protest after an alleged racist incident by a match official directed at the assistant manager of İstanbul Başakşehir.[6] The match was resumed on 9 December 2020, 18:55 CET, with a new team of match officials.