- Pro-Com Systems
- Pro-Pak Industries
- Proceed Technical Resources, Inc.
- Procter and Gamble Company
- Proctor and Gamble Co.
- Produce Marketing Association
- Producers Co-Op
- ProEd Communications, Inc.
- Professional and Scientific Associates, Inc.
- Professional Association Management
- Professional Engineers of North Carolina
- Professional Examination Service
- Professional Golfers Association of America PGA)
- Professional Hospital Inc.
- Professional Mailing and Distribution Services
- Professional Marketing Services, Inc.
- Professional Meeting Management Services
- Professional Nursing Services
- Professional Photographers of America
- Professional Physical Therapy West Side
- Profitability Quality Security
- Programa de Transplante de Corazon, Centro Cardiovascular de Puerto Rico y del Caribe
- Progress Financial Corp.
- Progressive
- Progressive Education Center
- Prohealth Ocnomomowoc Memorial Hospital
- ProHealth Waukesha Memorial Hospital
- Project Access
- Project Hope
- Project Impact Augusta- East Central Health District
- Project Management Institute
- Project Resilience
- Project Ship - School Health Integrated Programs
- Projection Presentation Technology
- Prologue Research
- Promac, Inc.
- ProMedica Bay Park Hospital
- ProMedica Charles & Virginia Hickman Hospital
- ProMedica Flower Hospital
- Promedica International
- ProMedica Toledo Hospital and Toledo Children's Hospital
- Promise Hospital East Los Angeles - Suburban Medical Center Campus
- Promise Hospital of San Diego
- Promiseland Ministy
- Promos Express
- Promotion Marketing Association
- Promotional Products Association International
- Prost Executives
- Protect Alert Emergency Response Systems, Inc.
- Protherm Services Group LLC