C
- C and C Constuctions
- C G Impex
- C S Software Enterprise
- C Street Center
- C&C California
- C&C Group plc
- C&D Technologies, Inc.
- C-Change
- C-Murder (musician)
- C-SPAN
- C.F. Os Belenenses
- C.H. Robinson Worldwide, Inc.
- C.Neeon
- C.R. Bard, Inc.
- CA Osasuna
- CA Technologies
- Cabinet Office
- Cable & Wireless
- Cable Corporation of India
- Cablevision
- Cablevision Systems Corporation
- Cabot Corporation
- Cabot India
- Cachao (musician)
- Cacharel (designer)
- CACI International, Inc.
- Cactus League
- Cadbury India
- Cadence Design Systems, Inc.
- Cadence Pharmaceuticals, Inc.
- Cadila Healthcare
- Cadillac
- Cadillac Sky
- Cadiz, Inc.
- Cadmus Communications Corporation
- CAE INC
- Cafe Coffee Day
- Cafepress
- Cage The Elephant
- Cagliari Calcio
- Cahya Mata Sarawak Berhad
- Cairn Energy
- Cairn India
- Caitlin Cary (musician)
- Cal Cougars
- Cal Dooley
- Cal Eldred
- Cal Odyssey
- Cal Poly Mustangs (basketball)
- Cal Poly Mustangs (football)
- Cal State Bakersfield Roadrunners (basketball)
- Cal State Fullerton Titans (basketball)
- Cal State Northridge
- Cal State Northridge Matadors (basketball)
- CalAmp Corp.
- Calcio Catania
- Calcom Vision
- Caldyn Aircon
- Caledonia Investments
- Calgary Flames
- Califone (musician)
- California Academy of Sciences
- California Air Resources Board
- California Baptist University
- California Coastal Commission
- California Collegiate Athletic Association
- California Community Foundation
- California Department of Corrections and Rehabilitation
- California Golden Bears (basketball)
- California Golden Bears (football)
- California Highway Patrol
- California Horse Racing Board
- California Institute for Regenerative Medicine
- California Institute of Technology
- California Lutheran University
- California Maritime Academy
- California Pizza Kitchen, Inc.
- California Polytechnic State University-San Luis Obispo
- California Public Utilities Commission
- California Software
- California State Polytechnic University-Pomona
- California State University
- California State University San Bernardino
- California State University, Fullerton
- California State University-Chico
- California State University-Fresno
- California State University-Long Beach
- California State University-Northridge
- California State University-Sacramento
- Californians Against Hate