| Owl City | Pop |
| Ozuna | Other |
| Outkast | Hip-Hop |
| Ozzy Osbourne | Rock |
| Offspring | Rock |
| Original Broadway Cast Recording | |
| Olivia Newton-John | Pop |
| OMD | Pop |
| Otis Redding | R&B |
| Opus | Rock |
| Opick | Pop |
| Oak Ridge Boys | Country |
| Orient Pearl | |
| Of Monsters And Men | Rock |
| Ouran High School Host Club | Pop |
| ONE OK ROCK | Rock |
| Old Crow Medicine Show | Country |
| The O'Jays | |
| ODESZA | Electronic |
| Olivia | Rock |
| Omi | Other |
| Overkill | Metal |
| Ogie Alcasid | |
| Olly Murs | Pop |
| OPM | Rock |
| Olafur Arnalds | Rock |
| Oscar Isaac | |
| Outlaws | Rock |
| Old Dominion | Rock |
| The Outfield | Rock |
| Old 97's | Rock |
| Outhere Brothers | Pop |
| Omarion | Pop |
| Over October | Other |
| Oingo Boingo | Rock |
| Over The Rhine | Country |
| Our Lady Peace | Rock |
| Offset | Rock |
| Original Broadway Cast | |
| Oleta Adams | Pop |