The Women's 100 metre backstroke competition of the 2020 European Aquatics Championships was held on 20 and 21 May 2021.

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

The following new records were set during this competition.

[6] The race was then declared void after the Swedish protested that the speaker in lane 1 malfunctioned and Hansson was not able to hear the starting gun.

The final re race was held on 21 May at 20:45.