| Zenith Investment Holding plc | |
| Zenner Ltd | |
| Zenobē Energy Ltd | |
| Zenopolis | Essex |
| ZenRows | |
| Zenstores | Bristol |
| Zenta Digital | |
| Zenzero Solutions Ltd | Warwickshire |
| Zenzic-UK Ltd | |
| Zephi | Staffordshire |
| Zepko | West Midlands |
| ZEPS | |
| Zepto Systems Ltd | Greater London |
| Zero Deposit | |
| Zero Install | Hampshire |
| Zero Point Motion | |
| Zero Tolerance Solutions Ltd | |
| Zero-1 | Derbyshire |
| zero8 Web Design & Build | East Sussex |
| Zerographic | Staffordshire |
| Zeroheight | |
| ZeroLight Ltd | Tyne and Wear |
| ZeroTouch Ltd | Berkshire |
| Zervant | Warwickshire |
| Zerve AI Ltd | |
| Zest Digital Ltd | |
| Zestcode Digital | Northamptonshire |
| Zeta Softwares | |
| ZetaPay Ltd | |
| ZetaSoft Ltd | West Sussex |
| Zeti Ltd | |
| ZetinIT Solutions Ltd | Cardiff |
| Zetta Genomics Ltd | |
| Zettasphere Ltd | Dorset |
| Zeus Electronics | Greater London |
| Zeus Labs Ltd | |
| Zevvle | Greater London |
| Ziath Ltd | |
| Zidivo | Worcestershire |
| Ziggurat Ltd | Cheshire |
| Ziglu Ltd | |
| ZigZag Global | |
| Zigzag Web Design | East Sussex |
| ZigZak Computers Ltd | |
| Zilabee | Berkshire |
| Zilch | Greater London |
| ZILO Technology Ltd | |
| Zimdesk Ltd | Tyne and Wear |
| ZIN Technologies Ltd | Greater London |
| Zinc Systems | |