Japan competed at the 2017 World Aquatics Championships in Budapest, Hungary from 14 July to 30 July.

Japan has entered 5 divers (two male and three female).

[1] Japan has entered six open water swimmers[2][3] Japanese swimmers have achieved qualifying standards in the following events (up to a maximum of 2 swimmers in each event at the A-standard entry time, and 1 at the B-standard):[4] Japan's synchronized swimming team consisted of 14 athletes (1 male and 13 female).

[5] Legend: (R) = Reserve Athlete Japan qualified both a men's and women's teams.

[6][7]