Swimming at the 2023 World Aquatics Championships – Men's 400 metre individual medley

The men's 400 metre individual medley competition at the 2023 World Aquatics Championships was held on 23 July 2023.

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

The following new records were set during this competition.

Heats
The heats were started at 12:52.

Final
The final was started at 21:21.