| TouchRight Software | |
| Touchstar ATC Ltd | East Sussex |
| TouchStone Capital Group Holdings Ltd | |
| Toughfruit Digital | Devon |
| Toward | |
| Tower Studios | |
| TownsWeb Archiving Ltd | Northamptonshire |
| Toxik Software | Cambridgeshire |
| TPXimpact Ltd | |
| TQC Ltd | Nottinghamshire |
| TR Computers | Cheshire |
| TR Control Solutions Ltd | Surrey |
| Trac Communications Ltd | North Yorkshire |
| Trace Services | Hertfordshire |
| Trace Web Design | Dorset |
| Traced Ltd | |
| Trackdown Consultants | Herefordshire |
| Tracker Intelligence | Glasgow |
| Trackershop-UK | Greater London |
| Tracsis plc | |
| Tractable Ltd | Greater London |
| Traction Charger Company Ltd | Wiltshire |
| Tracware Ltd | Isle of Wight |
| Trade & Investment Wales | |
| Trade Finance Global | |
| Trade Interchange Ltd | North Yorkshire |
| Trade Laptop Repairs | |
| Trade Scanners | Buckinghamshire |
| Trade Web Solutions Ltd | Derbyshire |
| Trade-Soft | |
| Trading Apps Ltd | |
| TradingHub | |
| TradingView | |
| Traffic Digital | Greater London |
| Traffic Giant | Edinburgh |
| Trafiki Ecommerce | Greater London |
| Train Effective Ltd | |
| Traineasy | Buckinghamshire |
| Training Link | Staffordshire |
| TrakCel | |
| Traktion Technologies Ltd | |
| Tramshed Tech | |
| Tranex Telecommunications Ltd | Northamptonshire |
| Trans Spectra Ltd | Staffordshire |
| Transcend Marketing | |
| Transcendit Ltd | Tyne and Wear |
| Transeo Media Ltd | |
| TransferGo Ltd | |
| TransFICC | |
| Transfinite Systems Ltd | Greater London |