| Barcodestore.co.uk | West Sussex |
| Bardford Web Design | West Yorkshire |
| Barefoot Web | East Sussex |
| Baresquare | |
| Bargain Hardware | |
| Barinthus Biotherapeutics plc | |
| Bark Digital Ltd | |
| Bark.com Global Ltd | |
| BarkWeb Ltd | East Sussex |
| Barnard Microsystems Ltd | |
| Barnsley IT support | South Yorkshire |
| Barr Media | |
| Barracuda Computer Solutions Ltd | Somerset |
| Barracuda Digital Ltd | Greater London |
| Barritel Ltd | Surrey |
| Barry Martin Computers | Nottinghamshire |
| Barry's Web Design | Dundee |
| Barsbank Ltd | Lancashire |
| Base Computer Services Ltd | Greater London |
| Base4.co.uk | |
| Basecamp Liverpool | |
| Basecamp Research | |
| Baseimmune | Greater London |
| Baseimmune | |
| BaseKit Platform Ltd | |
| Baselime | |
| Baseline Creative Ltd | Bristol |
| Baseline Vision Ltd | |
| BASETrack Systems Ltd | West Sussex |
| Basic Business Systems Ltd | Nottinghamshire |
| Basinhall Partners Ltd | |
| Basis Technologies | Greater London |
| Bassett Electronic Systems Ltd | Wiltshire |
| Bastion Therapeutics | Greater London |
| Bath Communication Systems Ltd | Somerset |
| Bath Computer Services | |
| Bath Spa University | |
| Bauer Technologies Ltd | |
| Baydrift Systems Ltd | |
| Bayes Server Ltd | West Sussex |
| BazaarBuilder | West Midlands |
| Bazil Guernsey | Channel Islands |
| Baztex Computers | Highland |
| BB Online UK Ltd | Bedfordshire |
| BB Online UK Ltd | |
| BBI Brandboost | Buckinghamshire |
| BBN International Ltd | Shropshire |
| BCB Group | |
| BCG Consultants | |
| BCG Webdesign Ltd | |