Swimming at the 2023 World Aquatics Championships – Men's 100 metre butterfly

The men's 100 metre butterfly competition at the 2023 World Aquatics Championships was held on 28 and 29 July 2023.

Records
Prior to the competition, the existing world and championship records were as follows.

Heats
The heats were started on 28 July at 10:32.

Swim-off
The swim-off was started on 28 July at 12:55.

Semifinals
The semifinals were held on 28 July at 20:09.

Final
The final was started on 29 July at 20:42.