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.

Heats
The heats were started on 25 July at 11:32.

Final
The final was held on 26 July at 20:02.