- Oak Hill Capital Partners
- Oak Hill Partners
- Oak Street Health
- Oasis Hospice & Palliative Care
- Obvious Ventures
- OCA Ventures
- Ocala Fire Rescue
- Occupational Safety and Health Administration
- Ochsner Health System
- Odyssey Hospice
- ogether for Supportive Cancer Care
- Ohana Health Plan
- Ohio Department of Aging
- Ohio History Connection
- Ohio Living
- Ohio State University
- Ohio’s Hospice
- Ohio’s Hospice LifeCare
- Ohio’s Hospice of Dayton
- Ohio’s Community Mercy Hospice