| CGain Web Design & SEO | |
| CGL Systems | |
| CH Digital | Staffordshire |
| Chadwick Design Ltd | Lincolnshire |
| Chagency | |
| CHAIN Biotechnology Ltd | |
| Chalfont Web Design | Buckinghamshire |
| Chalvington Communications Ltd | East Sussex |
| Chameleon Studios Ltd | Cambridgeshire |
| Chameleon Technology (UK) Ltd | North Yorkshire |
| Chameleon Web Services Ltd | |
| Chameloeon Media | Hampshire |
| Changingday Ltd | |
| Channel 3 Consulting | |
| Channel Communication Services Ltd | Bristol |
| Channel Digital Ltd | Cornwall |
| ChannelDoubler | Greater London |
| Chant 4 | Nottinghamshire |
| Chaos Design Ltd | Surrey |
| Chapman Hamer Ltd | Worcestershire |
| Chaptr | Hampshire |
| char.gy Ltd | |
| Charco Neurotech | |
| Charcoalblue | |
| Charcroft Electronics Ltd | Powys |
| ChargedEV | |
| Chargepoint Technology Ltd | |
| Charisma | |
| Charle | |
| Charles Square | |
| Charlie Lounge | |
| Charlton Networks | Gloucestershire |
| CHARM Therapeutics | |
| Charnwood Discovery | Leicestershire |
| Charnwood Molecular | |
| Chartered Developments | |
| ChartPixel Ltd | |
| Chartus Ltd | Gloucestershire |
| Chartwell-Yorke Ltd | Greater Manchester |
| Chaser Technologies Ltd | Greater London |
| Chatamo | |
| ChatBotKit | |
| ChatCSV | |
| Chatloop Ltd | |
| Chatsworth Media | Derbyshire |
| Chatterbox Ltd | Surrey |
| Chattermill | |
| Chawla Systems | |
| Chayn | |
| Cheadle DATA Recovery Ltd | Greater Manchester |