- O
- OO
- OO
- OOak
- OakObe
- ObeObs
- ObsOce
- OceOct
- OctOdd
- OddODE
- ODEOdu
- ODVOff
- OffOG
- OGOh
- OHOhm
- OhmOjo
- OjoOki
- OkiOla
- OlaOld
- OldOle
- OleOli
- OliOlo
- OloOma
- OmaOme
- OmeON
- ONOne
- OneONE
- ONEOne
- OneOnl
- OnlOnu
- OnwOpa
- OpaOph
- OphOR
- OrOrb
- OrbOrc
- OrcOre
- OreOri
- OriOrk
- OrkOrp
- OrpOrs
- Orsory
- OrzOsc
- OscOsl
- OslOst
- OstOti
- OtiOtt
- OttOur
- OurOut
- OutOut
- OutOve
- OveOve
- OveOwe
- OweOxm
- OXOOzo
- OzoOZZ
- O.S.T.R. feat. J, Brother
- O.S.T.R. feat. Kali
- O.S.T.R. feat. Playground Zer0
- O.S.T.R. feat. Sadat X & Cadillac Dale
- O.T. Genasis
- O.T. Genasis feat. Young Dolph
- O.T. Quartet
- O.Torvald
- O.W.L.
- O.Z (Mongolian R&B, Pop singer)
- O'2L
- O'Bir, Jon (Trance/Progressive-Trance DJ & producer from Nottingham, UK and based in Manchester, UK)
- O'Bir, Jon feat. Fisher
- O'Bir, Jon feat. Harrington, Julie
- O'Blivion, Monty (LA darkwave)
- O'Boy (french rapper)
- O'Boyle, Maeve
- O'Brien Sisters, The
- O'Brien-Docker, Ian
- O'Brien, Charlie (singer and filmmaker)
- O'Brien, Chris (US Singer-songwriter)
- O'Brien, Connor
- O'Brien, Joseph (production music composer)
- O'Brien, Joseph (Christian Artist)
- O'Brien, Michael (US AOR/christian vocalist)
- O'Brien, Michael (US christian singer/songwriter, member of Newsong)
- O'Brien, Mollie
- O'Brien, Paul
- O'Brien, Paul, The, All Stars Band
- O'Brien, Sinead (Irish punk poet)
- O'Brien, Tim & Scott, Darrell
- O'Brien, Tim & Scott, Darrell
- O'Bros (O'Bros from Munich, Germany)
- O'Callaghan, John & Larkin, Betsie
- O'Callaghan, John feat. Cathy Burton
- O'Callaghan, Patricia
- O'Clock, Apes
- O'Connor, Geoffrey
- O'Connor, Hazel
- O'Connor, Katie (Songwriter from Galway, Ireland)
- O'Connor, Mark's Hot Swing Trio
- O'Connor, Nora
- O'Connor, Tony (New Age composer)
- O'Day, Anita & Tjader, Cal
- O'Day, Anita with May, Billy
- O'Day, Aubrey
- O'Doherty, David
- O'Donis, Colby feat. Akon
- O'Donnell, Daniel & Duff, Mary
- O'Dowd, Erin
- O'Flaherty, Jack (Jack Fla)
- O'funk'illo
- O'Hara, Eureka
- O'Hara, Helen
- O'Hara, Maureen
- O'Hara, Paige, Benson, Robby, Orbach, Jerry, Lansbury, Angela and Stiers, David Ogden
- O'Hara, Paige, White, Richard and Chorus
- O'Hearn, Patrick (American drummer and percussionist)
- O'Hooley & Tidow
- O'Kane, Damien (Northern Irish folk musician)
- O'Keefe, Laurence (British bassist of Jazz Butcher, Levitation & Dark Star)
- O'Landa Draper and Associates, The
- O'Malley, J. Pat
- O'Malley, Lenore
- O'Mara, Peter, Trio
- O'May, Pat (French musician)
- O'Neal, Jamie
- O'Neal, Juliana
- O'Neill Brothers, The (Tim & Ryan)
- O'Neill, Con
- O'Neill, David (Christian Trumpet Artist)
- O'Neill, Harper
- O'Neill, Jack
- O'Neill, Megan
- O'o (French pop duo (Victoria Suter & Mathieu Daubigné))
- O'Reilly, Lorkin
- O'Reilly, Noel (Active since 2019)
- O'Reilly, Ryan (the band)
- O'Ryan (Irish Musician)
- O's, The (Dallas bluegrass duo)
- O'Shea
- O'Shea, Brendan
- O'Shine, Simon & Romel, Ahmed
- O'Sullivan, Camille
- O'Sullivan, Eoghan
- O'Sullivan, Gilbert feat. Lee, Peggy
- O'Yaba
- O’, Gary (Canadian singer‐songwriter Gary O’Connor)
- O’Banion, John
- O’Beirne, Gerry (Irish guitarist)
