- ORZA PROJECT
- Old Doll
- Orquesta Aché
- Olsen Brothers (奥尔森兄弟)
- Optimist
- Ordo Equitum Solis (永远的乌托邦)
- Ola Gjeilo
- Oleg Boshniakovich
- Original Moscow Cast Of The Phantom Of The Opera
- Orlando Brown
- Omonimo
- Orchestral
- Obsidia
- Ours to Alibi
- Ovylarock
- Off The Record
- Orchestre de l'Opéra de Lyon
- Olia Tira
- Onix
- Orulico
- Oliver Moldan
- 欧华成
- Orquesta Sinfónica de la Radio Liublajana
- Okapi
- One On One
- Orquesta Philharmonia
- OK
- Ost & Meyer
- Old Man's Child
- Orchestra Francis Dupont
- Osher
- Oliver Daldry
- Outrageous Cherry
- Omme Kolsoum
- ODEE (오디)
- Otoemon-ayahiro SUMI
- Oxi
- O'yaba
- ONSTYLE
- おかもとえみ (okamotoemi)
- Ocean Waves
- Otf
- Orchester Armando Zulueta
- Olivier Chassain
- OTO
- Orgue Hammond Orchestra
- Oblivion Machine
- Orquesta de Pulso y Pua de la Universidad Complutense de Madrid
- Other Two
- O'Funk'Illo
- One Star Closer
- Oil 10
- Oded Nir
- 欧天勇
- Orchestra da Camera Dell'Arte
- Oshmusik
- Oregon Trail
- 오션 (OCEAN)
- One + One
- O.di
