| BusinessCloud | |
| BusinessGen Ltd | Cardiff |
| BusinessLDN | |
| BusiSoft Solutions | East Sussex |
| Busuu Ltd | |
| Busybee Web Design | Argyll and Bute |
| Butterworth Laboratories Ltd | |
| Buy It Direct Ltd | West Yorkshire |
| Buzz (Hessle) Ltd | |
| Buzz Digital | |
| Buzz Radar | |
| BuzzBoost | |
| Buzzin Media Ltd | Kent |
| BuzzMyVideos | |
| BuzzSumo Ltd | |
| Buzzword | West Sussex |
| BVM Ltd | Hampshire |
| BVNK Services Ltd | |
| BW3 | Tyne and Wear |
| BWD | |
| BYG Systems Ltd | |
| Bynd Ltd | |
| Bynx Ltd | Warwickshire |
| Byra Digital Marketing Ltd | |
| Byte IT Computers | |
| Byte London Ltd | |
| ByteBack Creative Services Ltd | |
| ByteBox | |
| Bytec Group Ltd | |
| ByteCorp Technologies | |
| Bytegrow | |
| Bytehouse | Hertfordshire |
| Bytemark Ltd | North Yorkshire |
| ByteMinds | |
| Bytes Ahead Ltd | |
| Bytes Technology Group Ltd | Surrey |
| Bytescale Ltd | |
| ByteSnap | West Midlands |
| Bytestock | |
| ByteTree Group Ltd | |
| Bytewise Solutions | |
| BYTRIX Technologies | |
| Bytronic Automation Ltd | Worcestershire |
| C Data Services Ltd | Hampshire |
| C Force Communications Ltd | |
| C the Signs Ltd | |
| C&CO | |
| C++ on Sea | |
| C-A-Solutions | Lancashire |
| C-BIA Consulting | |