- Olivers
- Oljato
- Oljato-Monument Valley
- Olmstead
- Olympus Shadows Estates
- Olympus View
- Ophir
- Oquirlane
- Oquirrh
- Oquirrh Hills Office Building Condo
- Oquirrh Hills Subdivision
- Oquirrh Hills Subdivision 2-4
- Oquirrh Hills Subdivision 5, 6, 8 and 9
- Oquirrh (historical)
- Oquirrh Shadows
- Oquirrh View
- Orangeville
- Orchard Corners Condominium
- Orchard Country Woods Condo
- Orchard Park Estates Subdivision Number One and Two
- Orchard Park Subdivision Number 3-7
- Orderville
- Orem
- Orem Station
- Osiris
- Ouray
- Oxford Manor Condominium