- O’Reilly, Kevan
- O’Reillys and the Paddyhats, The
- O’Riley, Christopher (American pianist)
- O’Rion, Alex
- O’Riordan, Dolores
- O’Rourke, Declan
- O’Rourke, Jim (US musician & producer)
- O’Shaughnessy, Ryan (Irish singer-songwriter and former actor)
- O’Shine, Simon & Navel, Adam
- O’Shine, Simon & Romel, Ahmed
- O’Sullivan, Daniel (British multi-instrumentalist and composer)
- O’Sullivan, Gilbert
- O’Sullivan, Gilbert & Lee, Peggy
- O’Toole, Rich
- O+S
- O5 & Radeček
- OAFF
- OAG
- Òai Star
- Oak (French post-rock band)
- Oak (Swedish Hardcore, Screamo)
- Oak Pantheon (American atmospheric black metal band)
- Oak Ridge Boys, The
- Oak, Ken
- Oak, Nadia
- Oak, Northern
- Oak, Pete
- Oak, Winona
- Oakahtoakseh (Finnish experimental folk & spoken word group)
- Oakdale Drive
- Oakenfold, Paul
- Oakenfold, Paul & Disfunktion feat. Spitfire
- Oakenfold, Paul & Fox, Cassandra
- Oakenfold, Paul & Goss, Matt
- Oakenfold, Paul feat. Amoeba Assassin
- Oakenfold, Paul feat. Asher D
- Oakenfold, Paul feat. Bisnow, Austin
- Oakenfold, Paul feat. Furtado, Nelly & Tricky
- Oakenfold, Paul feat. Goss, Matt
- Oakenfold, Paul feat. Ice Cube
- Oakenfold, Paul feat. Lacey, Tiff
- Oakenfold, Paul feat. McCluskey, Angela
- Oakenfold, Paul feat. Murphy, Brittany
- Oakenfold, Paul feat. Phillips, Grant-Lee
- Oakenfold, Paul feat. Spitfire
- Oakenfold, Paul feat. Tawiah
- Oakenfold, Paul feat. Tedder, Ryan
- Oakenfold, Paul feat. Thompson, Hunter S.
- Oakenfold, Paul feat. Torrini, Emilíana
- Oakenfold, Paul feat. Werner, Carla
- Oakenfold, Paul feat. Werner, Carla
- Oakenfold, Paul feat. Young, Christopher
- Oakenfold, Paul vs. Bambaataa, Afrika & Soulsonic Force
- Oakey, Philip & Moroder, Giorgio
- Oakey, Philip & Moroder, Giorgio
- Oakey, Philip with Moroder, Giorgio
- OAKK
- Oakland, Guy
- Oakland, Max
- Oakley Riot
- Oakley, Michael (U.K. synthwave artist/producer)
- Oakman (French band)
- Oaks & Fahia (Spanish prog group)
- Oaks, Chris (christian rapper)
- OaKs, The
- Oaktree (Belgian electronic music producer)
- Oakwite (Drum & Bass)
- Oakwood
- Oakwood Station
- Oar (Australia, Metal)
- Oasis (1991–2009 Britpop)
- Oasis (Omar-S and Shadow Ray)
- Oasis (’70s US rock band)
- Oasis 4you (Mexican Christian music group)
- Oasis Chorale
- Oates, Jackie
- Oates, John
- Oath (An alias of Steven Waddell, used in this Heavy Metal solo project based in Edinburgh, Scotland, UK, started in 2018.)
- Oath of Cirion
- Oath to Order (USA metalcore/deathcore)
- Oath, Das
- Oath, The (German heavy doom metal)
- Oathbreaker (Belgian post-black metal band)
- Oathless
- Oaths, The
- Oatmello
- Oattes, Bernard
- Oaty. (lo‐fi artist)
- OAU (OVERGROUND ACOUSTIC UNDERGROUND)
- OB (DnB Producer (North London))
