The Women's 100 metre butterfly competition of the 2020 European Aquatics Championships was held on 17 and 18 May 2021.

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

The heats were started on 17 May at 11:03.

[3] The semifinals were held on 17 May at 18:32.

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