- Oaks Mobile Home And Recreational Vehicle Park
- Oakville
- Oasis
- Oasis
- Oasis Mobile Home Park
- Oasis, Mono
- Oban
- Obie
- Obregon
- O'Brien
- Occidental
- Ocean Hills
- Ocean Park
- Ocean Roar
- Oceano
- Oceano Beach
- Oceanside
- Ockenden
- Ocotillo
- Ocotillo Wells
- Octol
- Odd Fellows Park
- Off Rock
- Ogilby
- Ogilvie Island
- Ohm
- Oil City
- Oil Junction
- Oildale
- Oilfields