The men's 100 metre backstroke competition of the 2018 FINA World Swimming Championships (25 m) was held on 11 and 12 December 2018.

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

The heats were started on 11 December at 10:52.

[2] The semifinals were started on 11 December at 19:17.

[3] The final was held on 12 December at 19:08.