- O.K. Chorale
- Ok City Ok
- OK Cobra
- OK Corral
- OK Cowboy !
- OK Go
- OK Hemingway
- OK Jive
- Ok Juhyeon
- OK KID
- Ok-Ma
- Ok! Misik
- OK OK
- OK Panic
- OK! Ryos
- Ok- Sam
- Ok Sam
- Ok Star Orchestra
- O.K. Subramaniam
- OK Sweetheart
- OK To Go
- OK Tokyo
- Ok Volca
- OK Zombie
- Oka
- 岡千秋
- 岡晴夫
- Oka Road
- Okabi
- 岡田奈々
- Okada Taxi a.k.a. Kanoe
- 岡田有希子
- Okahira Kenji
- 岡平健治
- Okai
- Okai
- Okaidja
- Okain