The Women's 100 metre butterfly competition of the 2018 FINA World Swimming Championships (25 m) was held on 15 and 16 December 2018 at the Hangzhou Olympic Sports Center.

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

The heats were started on 15 December at 10:22.

[3] The semifinals were held at 19:31.

[4] The final was held at 19:08.