| Key Systems Out of Home Software Ltd | |
| Key-Tech Ltd | Fife |
| Keyboard Specialists Ltd | West Midlands |
| KeyFocus Ltd | |
| Keyless Technologies | |
| Keyloop Holdings (UK) Ltd | West Yorkshire |
| KeyMate.AI | |
| Keynes Controls Ltd | Berkshire |
| Keypoint Solutions | |
| Keyring Network Ltd | |
| Keyron | |
| Keysource Group | West Sussex |
| Keystar Training Ltd | Essex |
| Keystep Solutions | |
| Keywick Computer Solutions | Berkshire |
| Keyzone Computer Products Ltd | Berkshire |
| Keza Studio | |
| KGC Innovations Ltd | |
| KGStudio | |
| Khaos Control Solutions Ltd | Lincolnshire |
| Kheiron Medical Technologies Ltd | Greater London |
| Khoma Ltd | |
| Khoo Systems Ltd | |
| Khwarizmi Ventures | |
| Ki Capital Ltd | |
| Kiba Labs | |
| KIC Computing Ltd | Lincolnshire |
| Kick ICT Group | |
| Kierweb | |
| Kiin Bio | |
| KIJO | |
| Kiko Ventures Ltd | |
| Killer-Byte Ltd | |
| Kilmac Ltd | |
| Kim Technologies Ltd | West Midlands |
| Kimbley IT Ltd | West Midlands |
| Kin and Carta plc | |
| Kin Social App | |
| Kin Studio Dundee | |
| Kin Works Ltd | |
| Kinapse | |
| Kind | |
| KinderSoft | Devon |
| Kindred Capital VC | Greater London |
| KINESSO | |
| Kinesthetic Games | Surrey |
| Kinetic Creative Ltd | |
| Kinetic Digital Marketing | West Midlands |
| Kinetic Internet Ltd | Essex |
| Kinetic plc | |