| ITM Communications Ltd | |
| ITM Components | Dorset |
| Itower Marketing | Kent |
| ITQ Digital Ltd | |
| iTrain Scotland | Edinburgh |
| ITRI Ltd | Hertfordshire |
| itris | Kent |
| ITRM | Greater London |
| ITRS Group Ltd | |
| ITS (Shetland) Ltd | Shetland |
| ITS Digital Ltd | Hertfordshire |
| ITS Ltd | |
| ITS Solutions | West Midlands |
| ITSA (UK) Ltd | Berkshire |
| ITSec® Ltd | Leicestershire |
| ITSM.tools | |
| ITSO Ltd | |
| ITSupportNow | Greater London |
| ITVET Ltd | Greater Manchester |
| itwebandcloud | |
| ITWORX UK | |
| it|venture | |
| it’seeze | |
| Iuvo Ltd | Worcestershire |
| IVC Technologies Ltd | Somerset |
| iVendi Ltd | |
| Ivy and White Marketing Ltd | |
| Ivy Tech | |
| Ivy-Tech | |
| IW Capital Ltd | |
| iWeb | Staffordshire |
| iWeb FTP | Staffordshire |
| iWeb Technologies Ltd | West Midlands |
| iwebsitez.com | |
| Iwoca Ltd | |
| IX Reach | Greater Manchester |
| IX Wireless Ltd | |
| Ixaka | Greater London |
| Ixchelsis Ltd | |
| IXICO plc | |
| Ixis | Cheshire |
| IYF Design | Lincolnshire |
| iztech Ltd | Kent |
| iZurch | |
| J & B Computer Services | |
| J & H Humphrey | Hampshire |
| J C Analytical Ltd | |
| J&J Systems | |
| J-TEQ Energy Ltd | |
| J.P. Leisure Ltd | Devon |