2021 FINA World Swimming Championships (25 m) – Men's 4 × 100 metre medley relay

The Men's 4 × 100 metre medley relay competition of the 2021 FINA World Swimming Championships (25 m) was held on 21 December 2021.

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 10:09.

Final
The final was held at 19:50.