| GGP Systems | Greater London |
| Ghekko Ltd | Cheshire |
| GHIJK | |
| Ghost Digital & Data Ltd | Essex |
| Ghost Web Design | Wiltshire |
| Ghosthorses | |
| GHXhosting.com Ltd | Gloucestershire |
| GI Outsourcing | |
| Giacom | |
| Giacom World Networks Ltd | East Riding of Yorkshire |
| GIANT Health | |
| Giant Peach | Wiltshire |
| Giant Software Ltd | |
| Giant Ventures Global, LLP | Greater London |
| Giantt Telematics | South Yorkshire |
| Gibe Digital Ltd | |
| Gibraltar Financial Services Commission | |
| Gibraltar Regulatory Authority | |
| Gibraltar Technologies | |
| Gibtelecom | Gibraltar |
| giffgaff Ltd | |
| Gifford Bioscience Ltd | |
| Giftcloud | |
| Giganet | |
| Gigante Computers | West Midlands |
| Gigarefurb | Greater Manchester |
| Gigatronix Ltd | Hampshire |
| Gigged.AI | |
| Gigstart | |
| GIK Media | County Durham |
| Gilbert Media Ltd | |
| GIMO Global Interactive Marketing Online Ltd | Greater London |
| Gimson Robotics Ltd | Bristol |
| Ginger | Highland |
| Ginger6 Retail Ltd | West Midlands |
| Giraffe | |
| Giraffe360 | |
| GIS-Point | |
| GitBreeze Ltd | |
| GitLive | |
| Gitter | |
| Gitwork Ltd | |
| Give The Dog a Bone Ltd | Cheshire |
| GiveMeGraphics.Net | Cambridgeshire |
| GivePenny | |
| Givey | |
| GizmoTronics | Greater London |
| GJK Consultants | |
| GK Information Technology Services | Vale of Glamorgan |
| GK Services Ltd | Bedfordshire |