| causaLens | |
| Causaly | |
| Causeway Technologies Ltd | Buckinghamshire |
| Causeway Therapeutics | |
| Cavendish | Monmouthshire |
| Cavendish Communications | East Sussex |
| Cayenne Red | Berkshire |
| Cayenne Web Development Ltd | Oxfordshire |
| Cayman National - Isle of Man | |
| Cayman Venture | Tyne and Wear |
| Caz Ltd | Bristol |
| Cazbah Ltd | |
| CB Digital Marketing | |
| CB IT Consultancy | |
| CB Technology Ltd | |
| CBC Computer Systems Ltd | South Yorkshire |
| CBCOM | Merseyside |
| CBL Data Recovery (Newcastle) Ltd | Tyne and Wear |
| CBM UK Ltd | |
| CBRE | |
| CBS Business Consulting Ltd | |
| CBT Solutions Ltd | Buckinghamshire |
| CC Electronics Ltd | Cheshire |
| CC Grant Tracker | Glasgow |
| CCC IT Solutions | Hampshire |
| CCL (Solutions) Group Ltd | Buckinghamshire |
| CCl Components Ltd | Glasgow |
| CCL Computers Ltd | West Yorkshire |
| CCL Logistics | |
| CCm Technologies | |
| Ccoin Network | |
| CCR Systems (UK) Ltd | West Yorkshire |
| CCS Leeds | West Yorkshire |
| CCS Ltd | |
| CCS Media Ltd | Glasgow |
| CcS satcom | Essex |
| CCT Group Ltd | East Riding of Yorkshire |
| CCTV Surveillance Ltd | Cambridgeshire |
| CD2 Solutions | Norfolk |
| CDE Systems Ltd | South Yorkshire |
| CDR Group | Derbyshire |
| CDS Networks Ltd | |
| CE Engineering (Europe) Ltd | Kent |
| Ceejay Software Ltd | Falkirk |
| Cefar Ltd | |
| CEI Exhibitions | |
| Cel Stores | Leicestershire |
| Celaton | Buckinghamshire |
| CELCAT | West Midlands |
| Celebro | Essex |