Ifaistos Lemnos, Rethymno Cretan Kings and Panionios decided not to participate in the Greek Basket League in the 2020–21 season, due to financial problems.

[1][2] Messolonghi won the A2 League championship, and was thus promoted to the first tier level, for the first time in its history.

Diagoras Dryopideon entered in the first league and absorbed by Ionikos Nikaias on 9 July 2020.

[3] The eight highest ranked teams in the regular season qualified for the playoffs.

It also counts the total stats for both regular season combined.