- Computing Technology Industry Association
- Computize Inc.
- Comstock Communications, Inc.
- Conagra Brands
- ConAgra Foods of Omaha, Nebraska
- ConAgra Foods of Sidney, Ohio
- Conair Group Inc.
- Concept Engineers Inc.
- Concho Valley Regional Food Bank
- Concierge Media Group, Inc.
- Concord Hospital
- Concord Hospital Laconia
- Concordia Lutheran Ministries
- Cone Health Wesley Long Hospital
- Conemaugh Health System
- Conemaugh Memorial Medical Center
- Conemaugh Meyersdale Medical Center
- Conemaugh Miners Medical Center
- Conemaugh Nason Medical Center
- Conference and Logistics Consultants, Inc.
- Conference Archives Inc.
- Conference Direct
- Conference Direct
- Conference Direct
- Conferon, Inc.
- Confluence Technologies, Inc.
- Congregation Agudas Achim
- Congregation Kol Ami
- Congregational Health Ministry
- Congress of National Black Churches
- Congressional Black Caucus Foundation, Inc.
- Congressional Institute Incorporated
- Conley Group
- Connecticut Association of Not for Profit Providers for The Aging
- Connecticut Association of Not-For-Profit Providers for T
- Connecticut Association of School Business Officials
- Connecticut Children's Medical Center
- Connecticut Convention and Visitors Bureau
- Connecticut Primary Care Association
- Connecticut River Valley and Shoreline Visitors Council
- Connecticut State Legislature
- Connecticut VNA
- Connectivity Solutions man
- ConnectLife
- Connects Federal Credit Union
- Conoco
- Conoco Phillips
- Conor Medsystems
- Conotti Corporation
- Conquest Systems