- Orbital
- Orbitz
- Orbus
- Orchard Hotel, San Francisco
- Oregon Alliance of Senior and Health Services
- Oregon Business District Association
- Oregon Convention Center
- Oregon Health and Science University Hospital
- Oregon Nisei Veterans
- Oregon State Pharmacists Association
- Orem Community Hospital
- Organ Donor Awareness Foundation
- Organ Recovery Systems
- Organic Media Inc.
- Organization Management Services
- Organized Community Action Program
- Orlando - Hilton Garden Inn Sea World, FL
- Orlando Chapter of Alpha Kappa Soroity
- Orlando Clinical Research Center
- Orlando Health
- Orlando Health Arnold Palmer Hospital
- Orlando Health H. Central Hospital
- Orlando Health Health Central
- Orlando Health Horizon West
- Orlando Health South Seminole Hospital
- Orlando Health St. Cloud Hospital
- Orlando Orange County Convention and Visitors Bureau
- Orlando Regional Chamber of Commerce
- Orlando Regional Medical Center
- Orlando Union Rescue Mission
- Orlando VA Medical Center
- Orlando-International Drive - Fairfield Inn by Marriott, FL
- Orlando-Orange County Convention and Visitors Bureau, Inc.
- Orlando-South - Fairfield Inn by Marriott, FL
- Orleans-Niagara BOCES
- Oro Valley Hospital
- Oroville Hospital
- Orrville Area United Way, Inc.
- Orthopaedic Research Society
- Orthopedic Specialty Hospital of Nevada
- OrthoVirginia
- Ortiz Cintron Family Insurance
- Orzark Tri-County Healthcare Consortium
- Osceola Community Hospital, Inc.
- Osceola County Co-Op Oil Co.
- Osceola County Sheriff's Office
- Osceola Regional Health Center
- Osceola Regional Medical Center
- Oscient Pharmaceuticals
- OSF Center for Health - Streator