O-P-S Records

O-Rama

O.J.J. Records

O.L.

Oak

Oak Records

Oasis

Oausa

Object Music

Obscure Alternatives

Obvious Moose

OC5

Ocean

Ocora

ODA

Ode

Ode Records

Ode Sounds & Visuals

Odeon

Odeon / Alhambra

Odin

Odyssey

Odyssey Music Network

Off The Hook

Offence Records

Official

Official Bootlegger! K.G.L.W.

Oglio Records

Ogun

Oh Boy Records

OJC

OKra Records

Old Homestead

Old Timey Records

Old Town Records

Oldie Blues

Olfactory

Olive Tree

Olivia

Olivia Records

Olle

Olle I Skratthult Project

Olmec

Olufsen Records

Olydor

Olympia

Olympic Records

Olympic Records (4)

Olympico

Om Hip Hop

Omari

Omega Records

Omni Arts

Omni Sound

Omni Sound Jazz

Omnisound

Omnisound, Inc.

Omnivore

Omnivore Recordings

Omplatten

OMV / Preisser

On The Air

On The Spot

On-U

On-U Sound

Onari

Ondine

One Little Independent Records

One Little Indian

One Little Indian / One Little Independent

One Nation One Mind Records

One Star Project

Onslo Record

ONYX

Onyx Records

Opal

Open

Open Air

Open Air Records

Open Records

Open Sky

Open Sky Records

Optimism

Opus

Opus 3

Opus One

OR

Orange House Records

Orange Tree Press, Inc. Records

Oresound

ORF

Orfeo

Orfeon

ORG

ORG Music

Organic Music

Oriel

Origin Records

Original

Original Cast

Original Cast Records

Original Jazz Classics

Original Music

Original Recordings Group

Original Records Group

Original Recoreds Group

Original Rock Classics

Original San Francisco Record Company

Original Sound

Orinda

Orinda Records

Orion

Orion Master Recordings

Orpheus

Orphic Egg

Orphic Egg / London Records

Ortho Jazz

Oryx

Oryx Romantic

Oscar Records

Ossum Possum

Our First Record

Our Gang Entertainment / Mirus Music

Out

Out Loud

Out Loud Records

Out Of Your Element

Out There Records

Out-Sider

Outsider

Outstanding Records

Ovation

Ovation Records

Oversea

Overseas

Overseas Records

Overtone

Overweight Rat

Owl

Owl Records

Oxford