- The Oriental Groove Association -- The Original Blind Boys Of Mississippi
- The Original Brothers of Love -- The Original Five Blind Boys of Mississippi
- The Original Flava Unit -- The Original Loner
- The (Original) Lost Gonzo Band -- The Original Pataas Pababa
- The Original Patershol Ragtimers -- The Original Three
- The Original Thug Life -- The Orion Lion
- The Orion Music Ensemble -- The Orphan Project
- THE ORPHAN TRAINS -- The Oscar Peterson Big 6
- The Oscars -- The Other 5
- The Other 99 -- The Other Four
- The Other Guy -- The Other Side of Morning
- The Other Side of Space -- The Otis and Carla Band
- The Otis Problem -- The Outatime Orchestra
- The Outback Singers -- The Outkast
- The Outlanders -- The Outlyers
- The Outnumbered -- The Outsiders
- The Outsiders -- The Overcomers
- The Overdogs -- The Ovulators
- The Owen Family -- The Oxford Farm Report
- The Oxford Trio -- The Pace Family
- The Pace Setters -- The Package
- The Package -- The Pagans