Only transfers involving a team from the professional divisions are listed, including the 18 teams in the Belgian First Division A and the 8 teams playing in the Belgian First Division B.
The summer transfer window opened on 1 July 2021 and towards the end of August 2021.
Note that several transfers were announced prior to the opening date.
Furthermore, players without a club may join one at any time, either during or in between transfer windows.
After the transfer window closes a few completed transfers might still be announced a few days later.