O
- Ric Ocasek (Maverick/Warner Bros.)
- Maura O'Connell
- Mark O'Connor (Warner Bros. Nashville)
- Danny O'Keefe
- Oingo Boingo (Giant/Warner Bros.)
- Olive (Maverick/Warner Bros.)
- Ondar
- One 2 One
- William Orbit (Maverick/Warner Bros.)
- Outloud
- The Outriggers
Read more about this topic: List Of Former Warner Bros. Records Artists