- Outdoor swimming pool
- Office services
- Occupational safety and health
- Otolaryngology clinic
- Occupational medical physician
- Organic shop
- Oral surgeon
- Orthodontist
- Office equipment supplier
- Office furniture store
- Ophthalmology clinic
- Organic food store
- Organic restaurant
- Orphanage
- Osteopath
- Oil & natural gas company
- Oncologist
- Organic farm
- Outlet store
- Outdoor activity organiser