The Men's 100 metre butterfly competition of the 2020 European Aquatics Championships was held on 22 and 23 May 2021.

[1][2] Prior to the competition, the existing world, European and championship records were as follows.

The following new records were set during this competition.

The heats were started on 22 May 2021 at 10:37.

[4] The final was held on 23 May at 18:15.