| Callsign Ltd | |
| Callstream | West Midlands |
| Calm Digital | North Yorkshire |
| Calnex Solutions Ltd | West Lothian |
| Caltag Medsystems Ltd | |
| Caltech IT Ltd | West Yorkshire |
| Caltest Instruments Ltd | |
| Calyo | |
| Calyo Ltd | |
| Calyx | |
| Camb IT Support | Cambridgeshire |
| Cambertronics | Surrey |
| Cambio Ltd | |
| Cambrian Robotics Ltd | |
| Cambrian Software (UK) Ltd | Gwynedd |
| Cambridge Allergy Ltd | |
| Cambridge Analytical Laboratories | |
| Cambridge Angels | |
| Cambridge Bioscience | |
| Cambridge Broadband Networks Group | Cambridgeshire |
| Cambridge Circuit Company Ltd | Cambridgeshire |
| Cambridge Computer Support | Cambridgeshire |
| Cambridge Consultants Ltd | Cambridgeshire |
| Cambridge Electronic Design Ltd | Cambridgeshire |
| Cambridge Electronic Industries Ltd | Cambridgeshire |
| Cambridge Flow Solutions Ltd | Cambridgeshire |
| Cambridge GaN Devices | |
| Cambridge GCSE Computing | Cambridgeshire |
| Cambridge Innovation Capital Manager Ltd | Cambridgeshire |
| Cambridge Mechatronics Ltd | |
| Cambridge Medical Technologies Ltd | |
| Cambridge Micro Engineering Ltd | Cambridgeshire |
| Cambridge Mobile Communications Ltd | Cambridgeshire |
| Cambridge Network Ltd | Cambridgeshire |
| Cambridge Network Solutions Ltd | Cambridgeshire |
| Cambridge Networks Ltd | Cambridgeshire |
| Cambridge Nucleomics | |
| Cambridge PC Support | Cambridgeshire |
| Cambridge Protein Arrays Ltd | |
| Cambridge Science Park | Cambridgeshire |
| Cambridge Technology Consultants Ltd | Cambridgeshire |
| Cambridge Touch Technologies Ltd | Cambridgeshire |
| Cambridge Web Marketing Co. | Cambridgeshire |
| Cambridge Wireless | Cambridgeshire |
| Cambron Software Ltd | |
| Cambs Digital | |
| Cambs Web Design | |
| Camena Bioscience | |
| Cameron Wells | |
| CamGraPhIC Ltd | |