The Women's 50 metre butterfly competition of the 2018 FINA World Swimming Championships (25 m) was held on 13 and 14 December 2018.

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

The heats were started on 13 December at 09:40.

[2] The swim-off was held on 13 December at 11:02.

[3] The semifinals were held at 19:46.