The Men's 100 metre breaststroke competition of the 2018 FINA World Swimming Championships (25 m) was held on 11 and 12 December 2018 at the Hangzhou Olympic Sports Center.

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

The following new records were set during this competition: The heats were started at 11:25.

[2] The semifinals were held at 20:04.

[3] The final was held at 19:29.