# Swimming at the 2023 World Aquatics Championships – Men's 800 metre freestyle

The men's 800 metre freestyle competition at the 2023 World Aquatics Championships was held on 25 and 26 July 2023.

## 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 25 July at 11:32.
| Rank | Heat | Lane | Name | Nationality | Time | Notes |
| 1 | 3 | 5 | Samuel Short | Australia | 7:40.90 | Q |
| 2 | 3 | 1 | Ahmed Hafnaoui | Tunisia | 7:41.97 | Q |
| 3 | 3 | 3 | Lukas Märtens | Germany | 7:42.04 | Q |
| 4 | 4 | 6 | Daniel Wiffen | Ireland | 7:43.81 | Q, NR |
| 5 | 4 | 4 | Bobby Finke | United States | 7:43.87 | Q |
| 6 | 4 | 5 | Mykhailo Romanchuk | Ukraine | 7:44.07 | Q |
| 7 | 4 | 3 | Gregorio Paltrinieri | Italy | 7:44.89 | Q |
| 8 | 3 | 2 | Guilherme Costa | Brazil | 7:45.80 | Q |
| 9 | 3 | 4 | Florian Wellbrock | Germany | 7:45.87 | |
| 10 | 3 | 9 | Marwan Elkamash | Egypt | 7:46.55 | NR |
| 11 | 4 | 8 | Luca De Tullio | Italy | 7:46.87 | |
| 12 | 4 | 0 | Dávid Betlehem | Hungary | 7:47.02 | |
| 13 | 4 | 7 | Damien Joly | France | 7:47.44 | |
| 14 | 2 | 6 | Kim Woo-min | South Korea | 7:47.69 | NR |
| 15 | 2 | 2 | Kristóf Rasovszky | Hungary | 7:47.93 | |
| 16 | 2 | 7 | Alfonso Mestre | Venezuela | 7:48.66 | NR |
| 17 | 3 | 6 | Elijah Winnington | Australia | 7:49.24 | |
| 18 | 3 | 8 | Henrik Christiansen | Norway | 7:50.46 | |
| 19 | 4 | 1 | Ross Dant | United States | 7:54.23 | |
| 20 | 4 | 9 | Pacome Bricout | France | 7:55.20 | |
| 21 | 2 | 3 | Dimitrios Markos | Greece | 7:55.72 | |
| 22 | 2 | 4 | Luke Turley | Great Britain | 7:55.84 | |
| 23 | 3 | 7 | Daniel Jervis | Great Britain | 7:55.92 | |
| 24 | 3 | 0 | Fei Liwei | China | 7:56.69 | |
| 25 | 2 | 5 | Carlos Garach | Spain | 7:59.52 | |
| 26 | 2 | 8 | Bar Soloveychik | Israel | 7:59.65 | |
| 27 | 2 | 9 | Aryan Nehra | India | 8:00.76 | =NR |
| 28 | 2 | 1 | Eric Brown | Canada | 8:01.41 | |
| 29 | 1 | 5 | Khiew Hoe Yean | Malaysia | 8:05.11 | NR |
| 30 | 2 | 0 | Zac Reid | New Zealand | 8:06.94 | |
| 31 | 1 | 4 | Righardt Muller | South Africa | 8:07.08 | |
| 32 | 1 | 3 | Mai Trần Tuấn Anh | Vietnam | 8:08.56 | |
| 33 | 1 | 6 | Glen Lim Jun Wei | Singapore | 8:09.90 | |
| 34 | 1 | 2 | Ratthawit Thammananthachote | Thailand | 8:14.87 | |
| 35 | 1 | 7 | Eduardo Cisternas | Chile | 8:18.06 | |
| 36 | 1 | 1 | Rodolfo Falcón Jr | Cuba | 8:20.35 | |
| 37 | 1 | 0 | Líggjas Joensen | Faroe Islands | 8:41.85 | |
| 38 | 1 | 8 | José Campo | El Salvador | 8:57.60 | |
| | 4 | 2 | Felix Auböck | Austria | DNS | DNS |

### Final

The final was held on 26 July at 20:02.
| Rank | Lane | Name | Nationality | Time | Notes |
| | 5 | Ahmed Hafnaoui | Tunisia | 7:37.00 | |
| | 4 | Samuel Short | Australia | 7:37.76 | OC |
| | 2 | Bobby Finke | United States | 7:38.67 | AM |
| 4 | 6 | Daniel Wiffen | Ireland | 7:39.19 | ER |
| 5 | 3 | Lukas Märtens | Germany | 7:39.48 | NR |
| 6 | 7 | Mykhailo Romanchuk | Ukraine | 7:43.08 | |
| 7 | 8 | Guilherme Costa | Brazil | 7:47.26 | |
| 8 | 1 | Gregorio Paltrinieri | Italy | 7:53.68 | |