- O Val Das Mouras
- O'Death
- O+trio
- O.B.I.
- O.n.E.
- Oak and Aster
- Oasis de Détente et Relaxation
- Oba Tenga
- Obscura Hail
- Obscurus Orbis
- Observing Penny's
- Obstinat
- Ocean Pleasant
- Ocenk Dellewa
- Ocie Elliott
- Octavio Suñé
- Odd Cherry Pie
- Odd Hugo
- Odd Nordstoga
- Odd Years
- Oddur
- Odessey And Oracle
- Odetta
- Odina
- Odón del Paganéu
- Of Monsters and Men
- Of the Wild
- Offbeat
- Ofra Fux
- Ohmar con H
- OHNOVA
- Ohrange
- Ohtis
- Oido
- Oinasmaa
- Okan Şen
- Ol' Frogman Willis
- Ol' Savannah
- Ola Belle Reed
- Olav Stedje
- Old Boy
- Old Kid
- Old Oaks
- Old Oaks
- Oldaness
- Olden
- Ole Evenrud
- Olentangy John
- Olga
- Olga Cerpa y Mestisay
- Oli Spleen
- Oliv
- Oliver Blessinger
- Oliver Miller
- Olivia Garcia
- Olivia Rose Keegan
- Olivia Ruiz
- Olle Hillström
- Ollie Dixon
- Olo Walicki
- OM Collective
- Omar Contreras
- Ombre!
- Omkar Patil
- Omni Maercklein
- Omnia
- On the Water
- One Boy Band
- One Million Dollar Band
- One Of Everything
- Oneding
- Oni Band
- Onions
- Onira
- Onkar Jawandha
- Oolitic
- Opaline
- Orange Garden
- Orc
- Orchestra Annalisa D'Aloia
- Orchestra Fireluche
- Orchestraccia
- Ordinaryo
- Oreka Tx
- Organ Morgan
- Organic Process
- Original Motion Pictures
- Orlando Swim Club
- Orlando Triolo
- Orpin Music India
- Orplid
- Orquesta Típica de Granada
- Orquestra De Harmónicas De Ponte De Sôr
- Orrin Star
- Orson
- Orvnge
- Os Minhotos
- Oscar Lolang
- Oscar Macias Curupi
- Oscify
- Osho Jain
- Oskar Nyström
- Osma
- Osman Imeraj
- Osmer Martinez
- OSOG
- Oswald Sattler
- Otavio Nunes
- Otello Profazio
- Othala
- Otta
- Otto V.
- Oun Chakriya
- Out of View
- Outlines
- OutroEu
- Outside Kings
- Outta Nowhere
- Ovunda Ihunwo
- Owen "Snake" Chapman
- Owen Davies
- Owls By Nature
- Own Road
- OX
- Oxtered to the Bothy
- Oyster
- Oysterband