The 2020–21 ATK Mohun Bagan FC season was the club's 1st season in Indian Super League and 131st season since its establishment in 1889.

[2][3] The club under a merged company competed in ISL, one of the top flights of Indian football, as well as in the AFC Cup (because of delays, the AFC Cup campaign has been moved to 2021–22 season).

Source: ATK Mohun Bagan Squad Last updated: 25 September 2020Source: themohunbaganac.com Last updated: 13 March 2021 Source: Competitions

Last updated: 18 August 2021.

Source: Fbref Last updated: 13 March 2021.