| Converted | |
| Conveyd Ltd | |
| Conygre Consultants | Bristol |
| CookandKaye | Lancashire |
| CookieYes | |
| Cooknell Electronics Ltd | |
| Cool AV | Northamptonshire |
| Cool Components Ltd | Hampshire |
| Cool Hand Studios | |
| Coolbison Ltd | |
| CoolCare | West Yorkshire |
| Coolfields Consulting | |
| CoolSpools | |
| Cooper Engineering | Newry, Mourne and Down |
| Cooper Press Ltd | Lincolnshire |
| CoopSys | Greater London |
| COP Security | Greater Manchester |
| Copia Digital Ltd | |
| Copious | |
| Copley Scientific Ltd | |
| Copner Biotech Ltd | |
| Copper & Optic | Staffordshire |
| Copper Bay Digital | |
| Coprime Ltd | |
| Coptrz | |
| Copyin Ltd | |
| COR Solutions | Hertfordshire |
| Córas IT | |
| Corcym | |
| CORE | |
| Core 2 Computing | Renfrewshire |
| Core Digitalis | |
| CORE Internet Solutions Ltd | |
| Core Office IT | Devon |
| Core Oncology | |
| Core Power (UK) Ltd | |
| Core Technology System | |
| CoreAdviz Ltd | |
| Coreblue | |
| Corecom Consulting | |
| CoreFiling | Oxfordshire |
| Corefinity | |
| Corellasoft | |
| Coremaker | |
| Coremeta Ltd | |
| CoreScripts Technologies | |
| CoreStudio | |
| CoreTech Solutions Ltd | |
| Coriel Solutions | |
| Corient Business Solutions | |