| Boxclever | Bedfordshire |
| Boxharry Ltd | East Sussex |
| boxportable Ltd | Aberdeenshire |
| BoxStuff Ltd | Isle of Wight |
| BOXT | |
| Boxtobox | |
| Boxwell Web Design | |
| Boyd Consultants | |
| Boyd Digital | Glasgow |
| Bozboz | East Sussex |
| BP Ventures | Greater London |
| BPC Circuits Ltd | Leicestershire |
| BPP Holdings Ltd | |
| BPS Designs | Lancashire |
| BPWEB | Berkshire |
| BR-DGE | |
| Braci1 Ltd | West Midlands |
| Bradford College | |
| Bradford PC Repair | |
| Bradling Security Ltd | |
| Bradly Associates Ltd | Berkshire |
| Braemac Ltd | |
| Braided Communications Ltd | |
| Brainbox Webtech Ltd | Greater London |
| Brainboxes Ltd | Merseyside |
| Braindigit | |
| Brainomix Ltd | |
| Brainwave | |
| Brainwave AI Technologies Ltd | |
| Brainwave Discovery Ltd | |
| BrainWeb Ltd | Norfolk |
| BrainZ Digital | |
| Bramble Energy | |
| Bramfitt Technology Labs | |
| Branchspace | |
| Brand Communications Ltd | Cambridgeshire |
| Brand Dezign Ltd | |
| Brand House Group Ltd | |
| Brand Magic Media Ltd | Buckinghamshire |
| Brand Planet Ltd | |
| Brand Web Designs | Greater London |
| Brandan Computer Solutions Ltd | Devon |
| Brandbassador | |
| Brandshout | Cambridgeshire |
| Brandsites | |
| Brandwatch | |
| Brandworkz Ltd | |
| Bransom Retail Systems Ltd | Hertfordshire |
| Brass Agency | West Yorkshire |
| Brave Agency | |