The Men's 800 metre freestyle competition of the 2020 European Aquatics Championships was held on 21 and 22 May 2021.

[1][2] Before the competition, the existing world, European and championship records were as follows.

The heats were started on 21 May at 11:28.

[3] The final was held on 22 May 2021 at 18:00.

[4]