The Men's 100 metre butterfly competition at the 2017 World Championships was held on 28 and 29 July 2017.

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

The heats were held on 28 July at 10:10.

[3] The semifinals were held on 28 July at 18:35.

[4] The final was held on 29 July at 18:13.