The men's 800 metre freestyle event at the 2024 Summer Olympics was held from 29 July – 30 July 2024 at Paris La Défense Arena.

Prior to this competition, the existing world and Olympic records were as follows: The following record was established during the competition: Each National Olympic Committee (NOC) was permitted to enter a maximum of two qualified athletes in each individual event, but only if both of them had attained the Olympic Qualifying Time (OQT).

[2][3] Finally, the rest of the spaces were filled by athletes who had met the Olympic Consideration Time (OCT), which was 7:54.01 for this event.

The swimmers with the best 8 times in the heats advanced to the final.

Swim-offs were used as necessary to break ties for advancement to the next round.