The women's 800 metre freestyle competition of the 2018 FINA World Swimming Championships (25 m) was held on 12 and 13 December 2018.

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

The heats were started on 12 December at 11:25.

[2] The final was held on 13 December at 20:37.

[3]