| In3Bio | |
| Ina4 | Greater Manchester |
| Inaphaea BioLabs | |
| Inatech | |
| Inbest | |
| Incanthera Ltd | |
| Incanthera plc | |
| InCarCables Ltd | Buckinghamshire |
| inCase | |
| Incentive Games | |
| Incentivesmart Ltd | |
| inception2 Web Design | Hampshire |
| Inch Communications Ltd | Surrey |
| Inchware Ltd | Berkshire |
| Incito Systems Ltd | |
| Inclarity | Greater London |
| Included.co Ltd | |
| Inclusive Technology | |
| Incom Telecommunications | Greater Manchester |
| Incom-CNS Group | Greater Manchester |
| Inconnect Systems | |
| InControl Systems Ltd | Derbyshire |
| Incovo Ltd | West Lothian |
| Incube | |
| Incubeta | |
| Incus Technologies Ltd | |
| Incuto Ltd | |
| Independent Communication Solutions Ltd | Lincolnshire |
| Independent Financial Solutions | |
| Independent Training Services | South Yorkshire |
| Index Ltd | |
| Index Ventures | Greater London |
| INDEZ Ltd | Glasgow |
| Indicium Ventures | |
| Indigo Marmoset | Surrey |
| Indigo Software Ltd | County Durham |
| Indigo Technologies | |
| Indigoextra Ltd | Derbyshire |
| IndigoIdeas Ltd | |
| indigospring (Scotland) Ltd | Glasgow |
| Indos Computers | Hertfordshire |
| Indrum | East Sussex |
| Inductosense Ltd | |
| Industria Technology UK Ltd | Greater London |
| Industrial Computer Solutions | West Midlands |
| Industrial Electronic Controls Ltd | Kent |
| Industrial Electronic Services Ltd | West Midlands |
| Industrial Systems and Control Ltd | Glasgow |
| Industrial Vision Systems Ltd | Oxfordshire |
| InEn Global, LLP | |