O
- Of Montreal
- Oasis
- OutKast
- Okkervil River
- The Offspring
- OK Go
- Otis Redding
- Original Broadway Cast
- Ozzy Osbourne
- Old 97's
- Our Lady Peace
- O.A.R.
- Operation Ivy
- Opeth
- OneRepublic
- Old Crow Medicine Show
- Over the Rhine
- Office
- The Olivia Tremor Control
- Oingo Boingo
- Owen
- Os Mutantes
- Omarion
- Orishas
- Ozomatli
- The Orb
- Ours
- Orbital
- The One AM Radio
- Ol' Dirty Bastard
- Orchestral Manoeuvres in the Dark
- Ornette Coleman
- Oh No! Oh My!
- Orgy
- The Octopus Project
- Obie Trice
- Owl City
- Otep
- October Fall
- O-Town
- Overkill
- Oscar Peterson
- Oh No
- Ozma
- Ojos de Brujo
- Orange Juice
- The Oak Ridge Boys
- Ocean Colour Scene
- The O'Jays
- Odd Nosdam
- Original Soundtrack
- Omar Rodriguez-Lopez
- The Organ
- Olli Banjo
- O-Zone
- Obituary
- Oneida
- Outspoken
- The Outfield
- Ohmega Watts
- Oceansize
- Oxford Collapse
- Olivia Newton-John
- Over It
- Orange Range
- Of the Wand & the Moon
- Ost
- Operator
- The Ocean Blue
- Orson
- Oranj Symphonette
- Olive
- Out Hud
- Oakley Hall
- Odious Mortem
- Ozric Tentacles
- Onelinedrawing
- Omar
- Old Man Gloom
- Oddisee
- Orchestra Baobab
- OOIOO
- Oysterhead
- O'Death
- Oren Lavie
- The Only Ones
- Oomph!
- The Ocean
- Open Hand
- Ola Podrida
- Oceanlab
- Odetta
- Osker
- Oleander
- The Ordinary Boys
- Outrageous Cherry
- Organized Konfusion
- Orenda Fink
- Onyx
- Oppenheimer
