| Hayne Solutions Ltd | Warwickshire |
| Haynes | |
| Hays plc | |
| Hazy Ltd | Greater London |
| HBP Systems Ltd | Lincolnshire |
| HBTech | Hampshire |
| HC Technologies | |
| HCI York Ltd | North Yorkshire |
| HCOMS | Norfolk |
| HCP Cables Ltd | Hertfordshire |
| HCS Control Systems Ltd | |
| HD Create Ltd | Kent |
| HDANYWHERE | Worcestershire |
| HDD Software Ltd | |
| Head Office on365 Ltd | Leicestershire |
| Head45 | |
| HeadChannel Consulting Ltd | |
| Headlight AI Ltd | Greater London |
| HeadRed | West Midlands |
| Headstart App Ltd | |
| Headtex Ltd | Derbyshire |
| Headway Technology | West Midlands |
| Healome Therapeutics Ltd | |
| Health Innovation Manchester | |
| Health Innovation Network | |
| Health Intelligence | Cheshire |
| Health Private Ltd | |
| Health Sciences University | |
| Health Tech Alliance | |
| Health Tech Digital | |
| Health Tech World | |
| Health VR | |
| Healthcare Software Solutions Ltd | Nottinghamshire |
| Healthcode | Kent |
| Healthera Ltd | |
| HealthHero | |
| Healthily | |
| Healthy Pleasure Group Ltd | |
| Healx Ltd | |
| Heart Internet | Nottinghamshire |
| Heart IT Web Design Ltd | |
| HeartCMS | |
| Heata | |
| Heathfield Web Design | East Sussex |
| Heavy Penguin | |
| Heavyweight Digital Ltd | |
| Hedgehog Creations | |
| Hedgehog Digital | Bedfordshire |
| Hedgehog Lab | |
| Hedgewiz | |