Barrios de Washington O
- Ogden (6)
- Old Evergreen Highway (3)
- Olde Town (1)
- Olympic West (1)
- Opportunity (4)
- Orchards (1)
- Orchards Area (15)
- Outer Bremerton (19)
- Outer Mercer Island (4)
- Outer Silverdale (18)
- Outlying Issaquah (7)
- Outlying Lynnwood-Snohomish (33)
- Outlying McChord (10)
- Outlying Newcastle (10)
- Outlying Puyallup (21)
- Outlying Vancouver (19)
- Overlake (22)