- Ogden Regional Medical Center
- Ogden School District
- Ogden-Weber Convention Visitors Bureau
- Ogilvy Commonhealth Worldwide
- Ogilvy Public Relations
- Oh Heck! Marketing Comm. And Design
- Ohio Chinese American Professional Association
- Ohio Department of Education
- Ohio Department of Health
- Ohio Department of Transportation
- Ohio Dept. of Public Safety
- Ohio Dominican University
- Ohio Grand Council of Royal and Select Masons
- Ohio Grocers Association
- Ohio Historical Society
- Ohio Hospital Association
- Ohio Northern University
- Ohio Primary Care Association
- Ohio Rehabilitation Services Commission
- Ohio Society of Association Executives
- Ohio State University Medical Center -Managed Care
- Ohio State University Wexner Medical Center
- Ohio Trucking Association
- Ohio University
- Ohio University Inn, Athens
- Ohio University Zanesville
- Ohio Valley General Hospital
- Ohio Valley Medical Center
- Ohio Valley Tissue and Skin Center
- Ohio Veterinary Medical Association
- OhioHealth Berger Hospital
- OhioHealth Mansfield Hospital
- OhioHealth Marion General Hospital
- Ohiohealth O'Bleness Hospital
- OhioHealth Riverside Methodist Hospital
- OhioHealth Southeastern Medical
- Ohlone College
- Oki Data Americas, Inc.
- Oklahoma Association of Career and Technology Education
- Oklahoma Children's Hospital OU Health
- Oklahoma City
- Oklahoma City Convention and Visitors Bureau
- Oklahoma City Housing Authority
- Oklahoma City VA Health Care System
- Oklahoma Heart Hospital North
- Oklahoma Heart Hospital South
- Oklahoma Hospital Association
- Oklahoma Nurses Association
- Oklahoma Primary Care Association
- Oklahoma Public Employees Association