- Oxygen equipment supplier
- Office space rental agency
- Oil store
- Organic food store
- Observatory
- Oilfield
- Oral surgeon
- Orthodontist
- Oral and maxillofacial surgeon
- Off-road race track
- Oriental medicine store
- Office supply wholesaler
- Orchestra
- Outboard motor store
- Optician
- Orphanage
- Office equipment rental service
- Outdoor sports store
- Office refurbishment service
- Osteopath