2018 FINA World Swimming Championships (25 m) – Men's 400 metre individual medley

The Men's 400 metre individual medley competition of the 2018 FINA World Swimming Championships (25 m) was held on 15 December 2018.

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

Heats
The heats were started at 9:56.

Final
The final was held on 15 December at 20:22.