| Tinderhouse Ltd | Kent |
| Tinpeas Web Design | Suffolk |
| tinsleyNET | |
| Tinstar Design Ltd | Hampshire |
| Tiny Host | |
| Tiny Spark | |
| Tiny Supercomputer Management Company (UK) Ltd | Greater London |
| TinyOx | |
| Tioga Ltd | Derbyshire |
| TipTopJob.com | Berkshire |
| TISSL EPOS | Buckinghamshire |
| Tissue Regenix Ltd | |
| Tissue Solutions Ltd | |
| Tissuemed | West Yorkshire |
| Titan Academy | |
| Titan Internet Ltd | Essex |
| Titan Products Ltd | Greater Manchester |
| Titan Webtech Ltd | |
| Titania Ltd | Worcestershire |
| TitanML | |
| TIYO | |
| Tiziana Life Sciences | |
| TJ Design | |
| TJ Design UK | Northamptonshire |
| TJ Systems | Buckinghamshire |
| TJS Website Design | Lincolnshire |
| TK Webhosts | |
| TKM Consultants | |
| tKnowIT | North Yorkshire |
| TLA Systems | |
| TLC Business | |
| TLS Data Ltd | East Sussex |
| TM Domain Registry | Dorset |
| TMAX Media Ltd | Devon |
| TMC Pharma Services Ltd | |
| tmc3 Ltd | |
| TMS Media Ltd | Norfolk |
| TMT Consultants Ltd | |
| TMT ID | |
| TMT Investments plc | |
| tmWare | Staffordshire |
| TNG Designs Group Ltd | |
| TOAD | Greater London |
| Toast Design Consultancy Ltd | Oxfordshire |
| Toasted Design | East Sussex |
| Toaster | |
| Toby Electronics | Oxfordshire |
| ToCyber | |
| TOffeeAM | |
| Together Price Ltd | |