| Cledara Ltd | |
| CleerVu | Isle of Man |
| Cleo AI Ltd | |
| Clere Electronic Agents Ltd | Berkshire |
| Cleveland Circuits Ltd | North Yorkshire |
| Cleveland Technologies Group | North Yorkshire |
| Clever Cherry (Midlands) Ltd | West Midlands |
| Clever Computer Solutions Ltd | Derbyshire |
| Clever Software Group | Hampshire |
| Cleverbit | |
| Click Click Marketing Ltd | |
| Click Consult Ltd | Cheshire |
| Click Intelligence Ltd | |
| Click IT Services | West Yorkshire |
| Click Through Digital Ltd | |
| CLICK Web Development | Hampshire |
| Click4Assistance | Essex |
| Clickcartpro | Berkshire |
| ClickDo | |
| ClickInc.com | Isle of Man |
| ClickJump | |
| ClickMechanic Ltd | |
| Clicks Marketing | Cambridgeshire |
| ClickThrough Marketing | Staffordshire |
| Clicky Media Ltd | Cheshire |
| Client Software Ltd | |
| CLIFF Electronic Components Ltd | Surrey |
| Clifford Chance | |
| Clifton IT Ltd | Bristol |
| Clifton Media | Derbyshire |
| Clifton Web Design | Bristol |
| Climate Connect | Greater London |
| Climate Investment | |
| Climate X Ltd | |
| Climate.vc | |
| Climate17 | |
| ClimateAligned | |
| Climb Digital | |
| Climb Online Ltd | |
| Climber.eu | Greater London |
| Climbing Turn Ltd | |
| Clinical Design Technologies Ltd | |
| Clinical Metadata | |
| Clinical Software Solutions Ltd | |
| Clinical Supplies Management | |
| clinked.com | |
| Clive Angel | |
| Clock Ltd | |
| Clock Software | Greater London |
| clock.bio | |