| Toimi | |
| Tokenetic | |
| Tokyo | |
| Toltech Internet | Inverclyde |
| Tom Beavan | |
| Tom Starley UX | |
| Tomorrow People | West Midlands |
| Tomorrow People | |
| Tone Zone | West Sussex |
| Tongadive | |
| Tonic Analytics Ltd | |
| Tonik Studio | South Yorkshire |
| Tony Chapman Electronics Ltd | Buckinghamshire |
| Tony Demot | |
| Toolchefs Ltd | |
| Toolkit Websites Ltd | Hampshire |
| Top 10 Website Hosting | |
| Top Click Media Ltd | Surrey |
| Top Dog Digital | |
| Top Left Design | |
| Top Page SEO | Gloucestershire |
| Top Rank Studio Ltd | Greater Manchester |
| Top Spin Web Design | Worcestershire |
| Top Spot Optimisation | Hertfordshire |
| top5hosting.co.uk | |
| TopCV | |
| TOPPAN Digital Language | |
| TopSource Worldwide | |
| TopSys-IT | Greater Manchester |
| TopUniversities | Greater London |
| Toqio | |
| Tor Studio Ltd | |
| TOR Systems Ltd | Staffordshire |
| Torbay Pharma | |
| Torchbox | Oxfordshire |
| Torque Solutions Ltd | |
| Toru Ltd | |
| Total Computer and Network Support Ltd | Warwickshire |
| Total Data Management Ltd | |
| Total Digital | |
| Total Electronic Systems | Dorset |
| Total Enterprise Solutions | |
| Total Frequency Control Ltd | West Sussex |
| Total Integrated Solutions Ltd | Nottinghamshire |
| Total Labelling Solutions Ltd | Tyne and Wear |
| Total Network Technologies Ltd | Norfolk |
| Total Registrations | Greater Manchester |
| Total Results Ltd | Tyne and Wear |
| Total Security Ltd | |
| Total SEO & Marketing Ltd | |