| Holkirk Communications Ltd | |
| Holler Marketing | |
| HollowCore | |
| HOLO Digital | |
| Holoxica Ltd | |
| Holy Mackerel Software | Derbyshire |
| Home Control Solutions | |
| Home Helpdesk | |
| Home Lighting Systems Ltd | |
| Home Telecom | |
| Home-Computer-Fix | |
| Homeppl | |
| Homesearch | |
| HomeTouch Care Ltd | |
| Hone Bio Ltd | |
| Honest Logic | Cheshire |
| HoneyBee Marketing | |
| Honeycomb Software | |
| Hood Digital Ltd | |
| Hook Research Ltd | |
| Hook Solutions Ltd | |
| Hooley Research Ltd | |
| Hoopla Marketing | |
| Hootware Ltd | |
| Hopewiser Ltd | Greater Manchester |
| Hopin | Greater London |
| HopSoftware Ltd | |
| horion marketing | |
| Horisk Leslie Development Ltd | Fife |
| Horizon Computers | Somerset |
| Horizon Discovery Ltd | |
| Horizon Power and Energy Ltd | |
| Horizon Technologies Consultants Ltd | |
| Horizon Telecom Ltd | Gloucestershire |
| Horizon Web Development | Nottinghamshire |
| Horizon Web Solutions Ltd | |
| Horizone Group Ltd | |
| Hormonix | |
| Hornet Creative | Cambridgeshire |
| Horsham Web Design | West Sussex |
| Horyaal | West Midlands |
| Host Dada | |
| Host in Scotland | |
| Host iT Web Hosting | West Yorkshire |
| HOST Salford | |
| Host Surf UK Ltd | South Yorkshire |
| Hostcomm Ltd | |
| Hosteaze | |
| Hostek | |
| HostForLIFE | |