A total of 24 teams from 13 countries will participate in the 2020–21 EuroCup Basketball. Due to the prematurely ending of previous season caused by COVID-19 pandemic, the eight teams that qualified for the quarterfinals were awarded with guaranteed spots. The remaining spots were awarded to teams qualifying through their domestic leagues final standings. On 15 June 2020, the preliminary team list for the season was approved. 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by the ECA shareholders executive board, selecting Dolomiti Energia Trento to replace Fraport Skyliners who have withdrawn from the competition.
Teams
The labels in the parentheses show how each team qualified for the place of its starting round:
The schedule of the competition will be as follows.
Draw
The draw will be held on 10 July 2020 in Barcelona, Spain. Media and clubs representatives will not be allowed to attend the draw due to COVID-19 pandemic restrictions. The 24 teams will be drawn into four groups of six, with the restriction that teams from the same league could not be drawn against each other. For the draw, the teams are 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.
;Notes The fixtures will be decided after the draw, using a computer draw not shown to public, with the following match sequence: Note: Positions for scheduling do not use the seeding pots, e.g., Team 1 is not necessarily the team from Pot 1 in the draw.
There are scheduling restrictions: for example, teams from the same city in general are not scheduled to play at home on the same round.
Regular season
In each group, teams played against each other home-and-away in a round-robin format. The group winners, runners-up, third-placed teams and fourth-placed teams advanced to the [|Top 16], while the fifth-placed teams and sixth-placed teams were eliminated.
