| NIC.SH | Greater London |
| Nice Work Digital Ltd | |
| Niche Generics Ltd | |
| Nicholson Solutions Ltd | Aberdeen |
| Nick Ebdon Graphic Design | Kent |
| Nick McBurney Ltd | Greater Manchester |
| Nicomatic (UK) Ltd | Hertfordshire |
| Niftyz.io | |
| Night Zookeeper | |
| Nigma | |
| nijobfinder | |
| Nik Gill | |
| NIKAD Electronics Ltd | Buckinghamshire |
| Nikec Solutions | |
| Niki Peach Design | Oxfordshire |
| Nimans | Greater Manchester |
| Nimbla | |
| Nimble App Ltd | |
| Nimble AppGenie | |
| Nimble Delivery Ltd | |
| Nimbous Ltd | |
| NImbus Bestcables | Bedfordshire |
| Nimbus Blue Ltd | Aberdeen |
| Nimbus Hosting Ltd | Hertfordshire |
| Nine Software | |
| Nine Twenty Recruitment Ltd | |
| Nine2 | |
| Ninehundred Communications Group Ltd | South Yorkshire |
| Nineten | South Yorkshire |
| Ninevah Therapeutics | |
| Ninja PC Ltd | Northamptonshire |
| Nioute | |
| Niris Computer Services | East Sussex |
| Nirvana Intelligent Systems Ltd | Greater Manchester |
| Nirvaris Host | West Midlands |
| NISA Internet and Computer Solutions Ltd | |
| Niscam Ltd | Staffordshire |
| Nish Digital Ltd | |
| Nishtha Business Services Ltd | |
| NiSoft | Belfast |
| Nitec Solutions Ltd | Antrim and Newtownabbey |
| NiTech Solutions Ltd | |
| Nitel Ltd | Channel Islands |
| Nitro Foundry | |
| Nitronica | Newry, Mourne and Down |
| Nitronics Ltd | Hertfordshire |
| Nivoda Ltd | |
| Nixon McInnes | East Sussex |
| Nixuss Computer Repair & Support | |
| NK:IO Ltd | |