| Event: | Men's 400 metre freestyle |
| Competition: | 2021 FINA World Swimming Championships (25 m) |
| Venue: | Etihad Arena |
| Location: | Abu Dhabi, United Arab Emirates |
| Dates: | 16 December (heats and final) |
| Competitors: | 63 |
| Nations: | 54 |
| Win Value: | 3:35.90 |
| Gold: | Felix Auböck |
| Goldnoc: | AUT |
| Silver: | Danas Rapšys |
| Silvernoc: | LTU |
| Bronze: | Antonio Djakovic |
| Bronzenoc: | SUI |
| Prev: | 2018 |
| Next: | 2022 |
The Men's 400 metre freestyle competition of the 2021 FINA World Swimming Championships (25 m) was held on 16 December 2021.[1]
Prior to the competition, the existing world and championship records were as follows.
The heats were started at 09:30.[2]
| Rank | Heat | Lane | Name | Nationality | Time | Notes |
|---|---|---|---|---|---|---|
| 1 | 7 | 5 | 3:37.91 | Q | ||
| 2 | 5 | 7 | 3:38.61 | Q | ||
| 3 | 7 | 7 | 3:39.06 | Q, NR | ||
| 4 | 6 | 5 | 3:39.17 | Q | ||
| 5 | 7 | 2 | 3:39.34 | Q | ||
| 6 | 7 | 4 | 3:39.38 | Q | ||
| 7 | 4 | 6 | 3:39.52 | Q, NR | ||
| 8 | 6 | 3 | 3:39.53 | Q | ||
| 9 | 7 | 3 | 3:40.10 | |||
| 10 | 6 | 0 | 3:40.30 | |||
| 11 | 7 | 6 | 3:41.75 | |||
| 12 | 7 | 8 | 3:41.84 | |||
| 13 | 6 | 6 | 3:42.03 | |||
| 14 | 4 | 3 | 3:42.17 | |||
| 15 | 6 | 4 | 3:42.41 | |||
| 16 | 6 | 2 | 3:42.50 | |||
| 17 | 5 | 8 | 3:42.57 | NR | ||
| 18 | 4 | 4 | 3:43.27 | |||
| 19 | 5 | 4 | 3:43.35 | |||
| 20 | 6 | 7 | 3:43.43 | |||
| 21 | 7 | 1 | 3:43.58 | |||
| 22 | 5 | 1 | 3:43.64 | |||
| 23 | 4 | 1 | 3:43.89 | NR | ||
| 24 | 3 | 5 | 3:44.00 | NR | ||
| 25 | 4 | 5 | 3:44.23 | |||
| 26 | 5 | 0 | 3:44.83 | |||
| 27 | 5 | 6 | 3:44.90 | |||
| 28 | 6 | 1 | 3:45.01 | |||
| 29 | 6 | 8 | 3:45.66 | |||
| 30 | 7 | 9 | 3:45.74 | |||
| 31 | 5 | 2 | 3:46.05 | |||
| 32 | 4 | 7 | 3:46.08 | |||
| 33 | 3 | 2 | 3:46.43 | NR | ||
| 34 | 4 | 8 | 3:46.61 | |||
| 35 | 5 | 3 | 3:46.68 | |||
| 36 | 4 | 0 | 3:47.51 | NR | ||
| 37 | 5 | 5 | 3:48.05 | |||
| 38 | 4 | 2 | 3:48.07 | |||
| 39 | 7 | 0 | 3:48.12 | |||
| 40 | 3 | 4 | 3:49.01 | NR | ||
| 41 | 3 | 6 | 3:49.04 | NR | ||
| 42 | 3 | 3 | 3:49.13 | NR | ||
| 43 | 6 | 9 | 3:50.73 | |||
| 44 | 3 | 1 | 3:52.01 | |||
| 45 | 4 | 9 | 3:52.34 | |||
| 46 | 3 | 7 | 3:53.62 | |||
| 47 | 3 | 0 | 3:53.64 | NR | ||
| 48 | 3 | 9 | 3:53.66 | NR | ||
| 49 | 2 | 3 | 3:55.50 | NR | ||
| 50 | 2 | 4 | 3:55.55 | |||
| 51 | 2 | 5 | 3:57.51 | |||
| 52 | 1 | 3 | 3:58.31 | |||
| 53 | 3 | 8 | 3:59.11 | |||
| 54 | 2 | 1 | 3:59.93 | NR | ||
| 55 | 2 | 9 | 4:02.67 | |||
| 56 | 2 | 6 | 4:03.35 | |||
| 57 | 2 | 7 | 4:04.23 | |||
| 58 | 2 | 2 | 4:04.95 | |||
| 59 | 2 | 0 | 4:06.06 | |||
| 60 | 1 | 5 | 4:09.83 | |||
| 61 | 2 | 8 | 4:12.13 | |||
| 62 | 1 | 4 | 4:24.45 | |||
| 1 | 6 | DSQ | ||||
| 1 | 2 | DNS | ||||
| 5 | 9 |
The final was held at 18:00.[3]
| Rank | Lane | Name | Nationality | Time | Notes | |
|---|---|---|---|---|---|---|
| 4 | 3:35.90 | NR | ||||
| 7 | 3:36.23 | |||||
| 3 | 3:36.83 | NR | ||||
| 4 | 8 | 3:37.83 | ||||
| 5 | 5 | 3:38.77 | ||||
| 6 | 6 | 3:39.03 | ||||
| 7 | 1 | 3:39.06 | NR | |||
| 8 | 2 | 3:39.45 |