| 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 Designs | |
| Zinc Systems | |
| Zinc Ventures Ltd | Greater London |
| Zincweb Internet Ltd | Aberdeenshire |
| Zinia | |
| Zintech Ltd | Dorset |
| Ziontech | Somerset |
| Zipcube Ltd | |
| Ziptech Services Ltd | Surrey |
| Zircon Software | Wiltshire |
| Ziron (UK) Ltd | Oxfordshire |
| Zixus | Dorset |
| Zodiac Computers (East Middlands) Ltd | Derbyshire |
| Zodiac Media Ltd | Greater London |
| Zodiac Security Ltd | Somerset |
| Zoltan A. Vardy | |
| Zolv Ltd | West Yorkshire |
| Zonal | Edinburgh |
| Zonal Retail Data Systems | |
| Zonkey Solutions Ltd | Somerset |
| Zoocha | Hertfordshire |
| Zoocreative | Derry and Strabane |
| Zool Digital UK Ltd | Cheshire |
| Zoolz | Greater London |
| Zoonder Ltd | County Durham |
| Zoonou Ltd | |
| Zoopla Ltd | |
| Zoral | Greater London |
| Zorb Designs | |
| Zortrex Ltd | |
| Zouk Capital, LLP | |
| ZPos Ltd | |
| ZppiStore | Greater London |
| ZS Solutions Ltd | |
| zsah Managed Technology Services | Greater London |
| ZSOLNET Ltd | |
| Zuant | |
| Zubr | Bristol |
| Zubr Capital | Channel Islands |
| ZUDARO | |