- O.H.M.S.S. -- Óige
- 及川光博 -- oj trio
- OJ Vantage -- OK KID
- Ok-Ma -- Okay Temiz
- Okay Temiz Magnetic Band -- Oklahoma Tornadoes
- Oklahomo Trio -- Oktogon
- Oku -- Ola Håkansson
- Ola Herasymenko -- Olaf Sanders
- Olaf Schubert -- Olav Mol
- Olav Poulsen -- Old Coyote
- Old Coyote Moon -- Old Man Luedecke
- Old Man Mose -- Old Splendifolia
- Old Swan Band -- Oldie Börse
- Oldiendo -- Ole Jensen
- Ole Johansson -- Oleg Kagan
- Oleg Kireyev -- Olethrio Rigma
- Oleum -- Olga Maratse