Barrios de Ohio O
- Oakley (30)
- Oakwood (1)
- Ohio City (29)
- Old Brooklyn (27)
- Old Dayton (1)
- Old North Columbus (111)
- Old North Dayton (4)
- Old West End (7)
- Olde Orchard (1)
- Olde Sawmill (5)
- Olde Town East (27)
- Olde Town East-Columbus (21)
- Olde Towne (5)
- Olentangy (9)
- Olentangy Commons (2)
- Olentangy High Bluffs (3)
- ONYX (5)
- Oregon (4)
- Ottawa (38)
- Outer Canfield/Poland (5)
- Outer Canton (40)
- Outer Centerville/Kettering (55)
- Outer Dublin/Hilliard (35)
- Outer East Dayton (8)
- Outer East/Tallmadge (3)
- Outer Greater Hilltop (32)
- Outer Northeast (26)
- Outer Northeast Columbus (12)
- Outer Southern Columbus (19)
- Outer Upper Arlington (25)
- Over-The Rhine (25)