- APCO International
- Apex Environmental Inc.
- Apex Industries
- Apex Systems Inc.
- APICS
- APLABS
- Apogen Technologies
- Apollo Corporation
- Apostolic Christian Skylines
- Apostolou Associates
- Appalachian Behavioral Healthcare
- Appalachian Healthcare Project
- Appalachian Stove
- APPI Energy
- Applied Computer Technology, Inc.
- Applied Econometrics, Inc.
- Applied Measurement Professionals, Inc.
- Applied Technology Associates
- Appligent
- APrime Artistry
- APrime Services, LLC
- APS
- APT Information Technology Consultants
- Aptify
- Aptiv, Brookhaven
- Aqua America
- Aquascope Pools, Inc.
- Aquent
- Aquila Golf, Inc.
- Aramark
- Aranda Tooling, Inc.
- Arbor Acres United Methodist Retirement Community
- Arbor Terrace of Athens
- Arbor Tree Surgery, Inc.
- Arby's
- Arby's Restaurants
- Arc3 Gases
- Arcadia Association of Realtors
- Archdiocesan Housing Committee, Inc.
- Archdiocese of San Antonio
- Archer and Greiner
- Archer Bailey Gay Lodge #275
- Architects Dayton Thompson and Associates
- Arcos Communications
- Arden Courts
- ARDMS
- Area Agency on Aging of Northwest Arkansas
- Aria - Jefferson Health Bucks County
- Aria - Jefferson Health Torresdale
- Arizona Academy of Family Physicians