| 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 |
| Zoba Bank Ltd | Greater London |
| 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 | |
| ZoneMinder | Bristol |
| Zonkey Solutions Ltd | Somerset |
| Zoocha | Hertfordshire |
| Zoocreative | Derry and Strabane |
| Zool Digital UK Ltd | |
| Zoolz | Greater London |
| Zoonder Ltd | County Durham |
| Zoonou Ltd | |
| Zoopla Ltd | |
| Zoral | Greater London |
| Zorb Designs | |
| Zortrex Ltd | |
| Zouk Capital, LLP | |
| ZppiStore | Greater London |
| zsah Managed Technology Services | Greater London |
| Zubr | Bristol |
| Zubr Capital | Channel Islands |
| Zudu Ltd | Dundee |
| Zumo Financial Services Ltd | |
| Zumzum | Greater Manchester |
| Zupa | Hampshire |
| Zuru Media | Hampshire |
| Zut Games Ltd | |
| Zut Media | Merseyside |
| Zuti | Essex |
| Zycomm Electronics Ltd | Derbyshire |
| Zygo Consulting | Nottinghamshire |
| Zygology Systems Ltd | Buckinghamshire |
| Zynstra Ltd | Somerset |
| Zypha Technologies Ltd | |
| Zytec Systems (UK) Ltd | Leicestershire |
| Zytronic UK | Tyne and Wear |