Two warships of Japan have been named Ōi:
- Japanese cruiser Ōi, a Kuma-class cruiser launched in 1920 and sunk in 1944
- JDS Ōi, an Isuzu-class destroyer escort launched in 1963 and stricken in 1993
This article includes a list of ships with the same or similar names. If an internal link for a specific ship led you here, you may wish to change the link to point directly to the intended ship article, if one exists.