# Swimming at the 2024 World Aquatics Championships – Men's 800 metre freestyle

The men's 800 metre freestyle competition at the 2024 World Aquatics Championships was held on 13 and 14 February 2024.

## Records

Prior to the competition, the existing world and championship records were as follows.
| World record | Zhang Lin (CHN) | 7:32.12 | Rome, Italy | 26 July 2009 |
| Competition record | Zhang Lin (CHN) | 7:32.12 | Rome, Italy | 26 July 2009 |

## Results
### Heats

The heats were started on 13 February at 10:22
| Rank | Heat | Lane | Name | Nationality | Time | Notes |
| 1 | 4 | 2 | Luca De Tullio | Italy | 7:46.52 | Q |
| 2 | 4 | 4 | Daniel Wiffen | Ireland | 7:46.90 | Q |
| 3 | 5 | 5 | Sven Schwarz | Germany | 7:46.95 | Q |
| 4 | 4 | 9 | Victor Johansson | Sweden | 7:47.04 | Q, NR |
| 5 | 5 | 1 | Kristóf Rasovszky | Hungary | 7:47.19 | Q |
| 6 | 5 | 3 | Mykhailo Romanchuk | Ukraine | 7:47.20 | Q |
| 7 | 4 | 3 | Gregorio Paltrinieri | Italy | 7:47.38 | Q |
| 8 | 5 | 6 | Elijah Winnington | Australia | 7:47.59 | Q |
| 9 | 5 | 7 | David Betlehem | Hungary | 7:48.06 | |
| 10 | 4 | 5 | Florian Wellbrock | Germany | 7:48.17 | |
| 11 | 3 | 7 | David Johnston | United States | 7:48.20 | |
| 12 | 5 | 8 | Kuzey Tunçelli | Turkey | 7:48.53 | NR |
| 13 | 4 | 1 | Alfonso Mestre | Venezuela | 7:48.84 | |
| 14 | 2 | 4 | Dimitrios Markos | Greece | 7:49.97 | NR |
| 15 | 3 | 3 | Carlos Garach Benito | Spain | 7:50.56 | |
| 16 | 3 | 1 | Fei Liwei | China | 7:51.18 | |
| 17 | 5 | 0 | Henrik Christiansen | Norway | 7:51.21 | |
| 18 | 5 | 4 | Ahmed Hafnaoui | Tunisia | 7:51.72 | |
| 19 | 2 | 3 | Lucas Henveaux | Belgium | 7:52.10 | NR |
| 20 | 4 | 7 | Damien Joly | France | 7:53.42 | |
| 21 | 3 | 8 | Ilia Sibirtsev | Uzbekistan | 7:53.87 | NR |
| 22 | 3 | 5 | Charlie Clark | United States | 7:54.87 | |
| 23 | 5 | 9 | Zhang Zhanshuo | China | 7:55.86 | |
| 24 | 4 | 8 | Jon Joentvedt | Norway | 7:56.28 | |
| 25 | 3 | 9 | Shogo Takeda | Japan | 7:57.54 | |
| 26 | 3 | 6 | Felix Auböck | Austria | 7:57.63 | |
| 27 | 4 | 6 | Guilherme Costa | Brazil | 7:58.02 | |
| 28 | 2 | 2 | Khiew Hoe Yean | Malaysia | 8:02.78 | NR |
| 29 | 3 | 2 | Nguyễn Huy Hoàng | Vietnam | 8:05.17 | |
| 30 | 2 | 6 | Dylan Porges | Mexico | 8:05.83 | |
| 31 | 4 | 0 | Vlad Stancu | Romania | 8:06.50 | |
| 32 | 2 | 1 | Ratthawit Thammananthachote | Thailand | 8:06.82 | NR |
| 33 | 3 | 4 | Marc-Antoine Olivier | France | 8:08.54 | |
| 34 | 2 | 7 | Glen Lim Jun Wei | Singapore | 8:09.34 | |
| 35 | 3 | 0 | Juan Morales | Colombia | 8:11.31 | |
| 36 | 2 | 8 | Diego Dulieu | Honduras | 8:11.97 | |
| 37 | 2 | 9 | Loris Bianchi | San Marino | 8:17.70 | NR |
| 38 | 1 | 4 | Ilias El Fallaki | Morocco | 8:27.22 | |
| 39 | 1 | 5 | Alberto Vega | Costa Rica | 8:30.93 | |
| 40 | 1 | 3 | Liggjas Joensen | Faroe Islands | 8:32.54 | |
| 41 | 1 | 6 | Mal Gashi | Kosovo | 8:35.97 | |
| 42 | 2 | 0 | Rodolfo Falcón Jr. | Cuba | 8:38.90 | |
| 43 | 1 | 2 | Mohammed Al-Zaki | Saudi Arabia | 9:06.29 | |
| | 2 | 5 | Antonio Djakovic | Switzerland | Did not start | Did not start |
| | 5 | 2 | Kim Woo-min | South Korea | Did not start | Did not start |

### Final

The final was started on 14 February at 19:02.
| Rank | Lane | Name | Nationality | Time | Notes |
| | 5 | Daniel Wiffen | Ireland | 7:40.94 | |
| | 8 | Elijah Winnington | Australia | 7:42.95 | |
| | 1 | Gregorio Paltrinieri | Italy | 7:42.98 | |
| 4 | 3 | Sven Schwarz | Germany | 7:44.29 | |
| 5 | 2 | Kristóf Rasovszky | Hungary | 7:44.42 | NR |
| 6 | 6 | Victor Johansson | Sweden | 7:47.08 | |
| 7 | 4 | Luca De Tullio | Italy | 7:49.79 | |
| 8 | 7 | Mykhailo Romanchuk | Ukraine | 7:54.51 | |