In response to the premature ending of the previous season caused by the COVID-19 pandemic, the eight teams that qualified for the quarterfinals were awarded with guaranteed spots.

[2] On 22 June 2020, the team list was approved by the ECA shareholders executive board, selecting Dolomiti Energia Trento to replace Fraport Skyliners who have withdrawn from the competition.

[3] On 17 September 2020, Mornar Bar replaced Maccabi Rishon LeZion which was forced to withdraw due to logistical difficulties and financial concerns complicated by the COVID-19 pandemic.

[4] The labels in the parentheses show how each team qualified for the place of its starting round: A total of 70 Euroleague Basketball referees set to work on the 2020–21 season: The schedule of the competition is as follows.

Additionally, the deadlines to play any remaining rescheduled games ahead of the regular season and Top 16 were set on January 5, 2021 and March 16, 2021 respectively.

For the draw, the teams were seeded into six pots, in accordance with the Club Ranking, based on their performance in European competitions during a three-year period and the lowest possible position that any club from that league can occupy in the draw is calculated by adding the results of the worst performing team from each league.