A total of 16 teams participated, 13 of which competed in the league during the previous season, while the remaining three were promoted from the 2019–20 I liga.

On 24 July 2020 Ekstraklasa SA and Polish Football Association announced the 2020–21 season calendar.

[9] After winning the I liga promotion play-offs, Warta Poznań also returned to Ekstraklasa after 25 years.

[10] Legia Warsaw were the defending champions, and won their 15th title overall on 28 April after Raków Częstochowa drew 0–0 away to Jagiellonia Białystok with three games remaining.

[11] The season's runner-up was Raków Częstochowa, and the third-placed team was Pogoń Szczecin.