| HESH Computer Services Ltd | East Riding of Yorkshire |
| HestaBit | |
| Heveloon Ltd | |
| Hewitt Matthews | |
| Hex Security Ltd | |
| HexaExperts | |
| Hexagon Software Group Ltd | Gloucestershire |
| Hexatec | Northumberland |
| Hexiosec | |
| Hexology | |
| Heystack | |
| HeySuccess Ltd | |
| HeySummit | |
| Heywood&Sons Ltd | Greater London |
| Hg | Greater London |
| HHB Web Design Manchester | Greater Manchester |
| HI Technology & Innovation | |
| Hi-Tech Communications Ltd | Hertfordshire |
| Hibu Group Ltd | Berkshire |
| HICKS | Oxfordshire |
| HICX Solutions Ltd | |
| Hidden Creative Ltd | |
| Hidden Web Genius Solutions | |
| HiddenApp Ltd | |
| Hificables | West Sussex |
| HIFLY | |
| Higgs Centre for Innovation | |
| High Digital Ltd | |
| High Impact | |
| High Level Software | |
| High Profile Ltd | Kent |
| High Quality Technology Ltd | |
| High Speed Training Ltd | |
| High-Availability.com Ltd | Cheshire |
| Highblade Cables | Cumbria |
| Higher Education Statistics Agency | |
| HigherSites | Somerset |
| Highgrove | Leicestershire |
| Highland Broadband Networks Ltd | |
| Highland Europe | |
| Highland Learning Academy | Highland |
| Highland Network Ltd | Highland |
| Highlands and Islands Enterprise | |
| Highridge Computers | Staffordshire |
| Highrise Digital | Kent |
| HighThrive Digital | |
| HiJOBS Ltd | |
| Hikma Pharmaceuticals plc | |
| Hill Data Systems Ltd | |
| Hilvy Ltd | |