Performers are listed alphabetically by first name.
- O Children
- O Giant Man
- O, Don Piano
- O.A.R.
- O.N.E The Duo
- O'Brother
- O'Death
- Oak House
- Oakley Hall
- Oasis
- Oberhofer
- Obits
- Oceans Are Zeroes
- Ocote Soul Sounds
- October Project
- Odawas
- Odessa
- Odetta
- Odetta and Bob Gibson
- Odetta Hartman
- Odie Leigh
- Odonis Odonis
- Of Monsters and Men
- of Montreal
- Off Campus
- OFF!
- OFFICE
- Officer
- Oh My Love
- Oh No Oh My
- Oh No Ono
- Oh Pep!
- Oh So Quiet
- Oh Wonder
- Oh, Jeremiah
- OHMME
- Ohtis
- Oil Boom
- Oingo Boingo
- OK Bayou
- OK Go
- Okay
- Okey Dokey
- Okilly Dokilly
- Okkervil River
- Oko Tygra
- Ola Podrida
- Olafur Arnalds
- Old 97's
- Old Abram Brown
- Old Canes
- Old Ceremony
- Old Crow Medicine Show
- Old Dominion
- Old Light
- Old Lights
- Old Man Markley
- Old Monk
- Old Scratch Revival Singers
- Old Sea Brigade
- Old Time Machine
- Oleander
- Olin & The Moon
- Oliver and the Rockets
- Oliver Canidy
- Oliver Hazard
- Oliver Wood
- Olivia Castriota
- Olivia Ellen Lloyd
- Olivia Jean
- Olivia Neutron-John
- Olivia O'Brien
- Olivia Rose Muzzy
- Olivia Sebastianelli
- Olivver The Kid
- Ollabelle
- Olof Arnalds
- Olympians
- Omar & the Howlers
- OMB Peezy
- ON AN ON
- Ona
- Once & Future Band
- Ondi Timoner
- One EskimO
- One For The Team
- One Hundred Flowers
- One Night Stand
- Only Living Boy
- Onward Brass Band
- Onward etc.
- Open Mike Eagle
- Opio/Free The Robots
- Opossom
- Oppenheimer
- Options
- Or, the Whale
- Ora Cogan
- Oranger
- Oregon
- Orenda Fink
- Orgy
- Orixa
- Orleans
- Oropendola
- Orphan Colours
- Ortolan
- Oryx And Crake
- Oscar
- Oscar And The Wolf
- Oscar Brown, Jr.
- Oscar Peterson
- Oscar Peterson Trio
- Oso Oso
- Ossie Kilkenny, Michael Lang and John Scher
- Ostraca
- Other Lives
- Otis Rush
- Otis The Destroyer
- Otouto
- Otto-McLawler Trio
- Our Girl
- Our Lady Peace
- Ours
- Out of System Transfer
- Outer Spaces
- Outfit
- Outkast
- Outlaws
- Over Sands
- Over the Rhine
- Overcoats
- Owen
- Owen Beverly / French Camp
- Owens
- Owlle
- Oxford & Co.
- Oxford Collapse
- Oxymorrons
- Ozark Mountain Daredevils
- Ozomatli
- Ozzy Osbourne