- NYU Langone Hospital-Brooklyn
- NYU Langone Tisch Hospital
- NYU Langone Transplant Institute
- NYU Winthrop Hospital
- O'Callaghan Hotel Annapolis
- O'Connor Hospital
- O'Neil Printing
- O.C. Tanner
- Oak Forest Health Center - Cook County Health and Hospitals System
- Oak Hill Hospital
- Oak Manor Nursing Home, Inc.
- Oak street Health
- Oakdale Community Hospital
- Oakland Convention and Visitors Bureau
- Oakland County Board of Commissioners
- Oakland County Medical Society
- Oakland County, Michigan
- Oakland University
- Oakley Elementary School
- Oakwood Annapolis Hospital
- Oakwood Heritage Hospital
- Oakwood Hospital and Medical Center
- Oakwood Southshore Medical Center
- Oakwood Village
- Oatfield Estates
- OBGyn of Lancaster, Inc.
- OCA Westchester and Hudson Valley Chapter
- OCASA International
- Occasions Caterers
- Ocean Center
- Ocean Energy Inc.
- Ocean Springs Hospital
- Ocean Walk Village
- Oceaneering International Inc.
- Oceaneering Space and Thermal Systems
- OCG
- OCH Regional Medical Center
- Ochsner Baptist Medical Center
- Ochsner Clinic Foundation
- Ochsner Health System
- Ochsner LSU Health Monroe
- Ochsner LSU Health Shreveport-Academic Medical Center
- Ochsner Medical Center
- Ochsner Medical Center - Baton Rouge
- Ochsner Medical Center - Kenner
- Ochsner Medical Center - North Shore
- Ochsner Medical Center - West Bank Campus
- Ochsner Medical Center Hancock
- Ochsner St. Anne Hospital
- Oconee County Board of Commissioners