The Women's 100 metre breaststroke competition of the 2021 FINA World Swimming Championships (25 m) was held on 19 and 20 December 2021.

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

The heats were started on 19 December at 10:45.

[2] The semifinals were started on 19 December at 19:48.

[3] The final was held on 20 December at 19:42.