| Bowles Ltd | Wholesale & retail | 2023 |
| Bowstridge Court Management Limited | Real estate | 2007 |
| Boxdrop Ltd | Transport & logistics | 2025 |
| Boxlife Ltd | Wholesale & retail | 2026 |
| Boxmoor Show Jumps Limited | Education | 2003 |
| Boxmoor Trout Fishery Limited | Agriculture & fishing | 1976 |
| Bozbu Ltd | Wholesale & retail | 2025 |
| BP Convenience Ltd | Wholesale & retail | 2019 |
| BPJ Neuroimaging Ltd | Health & social care | 2020 |
| BR Digital Advertising Limited | Professional & scientific | 2024 |
| BR Roofing Limited | Construction | 2021 |
| Brackley Law Ltd | Professional & scientific | 2018 |
| Brackley Road LLP | | 2023 |
| Bradshaw Therapy and Wellbeing Ltd | Health & social care | 2025 |
| Bradshaw Windows and Doors Ltd. | Construction | 2024 |
| Brain Space Makeup Limited | Arts & recreation | 2025 |
| Brainflash Limited | Information & communication | 2009 |
| Brance Associates Ltd | Professional & scientific | 2019 |
| Branch Films Ltd | Information & communication | 2025 |
| Branchaffect Limited | Administrative & support | 2024 |
| Brand Corp Digital Innovation & Data Limited | Administrative & support | 2020 |
| Brand Direction Limited | Professional & scientific | 2025 |
| Brand Factory Limited | Wholesale & retail | 2018 |
| Branded Delights Ltd | Wholesale & retail | 2023 |
| Brandomco Ltd | Wholesale & retail | 2022 |
| Braticuta Ltd | Transport & logistics | 2018 |
| Brayon Solutions Limited | Information & communication | 2019 |
| Breakfast Milk Limited | Hospitality | 2017 |
| Breathe Safe Solutions Ltd | Professional & scientific | 2023 |
| Brecon Sword Ltd | Manufacturing | 2025 |
| Brempon & Sons Limited | Health & social care | 2020 |
| Brendeni Sons and Daughters Ltd | Wholesale & retail | 2026 |
| Brent I Limited | Energy | 2025 |
| Bresi Limited | Information & communication | 2024 |
| Breslin Workforce Solutions Ltd | Administrative & support | 2024 |
| Brettelec Services Limited | Administrative & support | 2012 |
| Breweire Ltd | Hospitality | 2016 |
| Brewster Construction Ltd | Construction | 2017 |
| Brian Edwards Timber Consultant Limited | Wholesale & retail | 2024 |
| Brian Long Consultancy & Training Services Ltd | Information & communication | 2006 |
| Brian Raven Limited | Construction | 2010 |
| Brian Wilson Design Ltd | Professional & scientific | 2025 |
| Brick & COS Limited | Construction | 2024 |
| Bridge England Limited | Other services | 2012 |
| Bridge Fleet Logistics & Partners Ltd | Transport & logistics | 2026 |
| Bridgeability Ltd | Professional & scientific | 2012 |
| Bridgetech Automotive Services Ltd | Administrative & support | 2022 |
| Bridgetech Connect Limited | Information & communication | 2018 |
| Bridgetech Group Ltd | Information & communication | 2018 |
| Bridgetech Group Services Ltd | Professional & scientific | 2022 |
| Bridgetech Software Ltd | Information & communication | 2019 |
| Bridgevines Limited | Other services | 2016 |
| Bridgeway Engineering Limited | Professional & scientific | 2019 |
| Bridle Rigging Limited | Professional & scientific | 2019 |
| Brighton Private Gyms Ltd | Health & social care | 2026 |
| Brightwall Exterior Cleaning Limited | Administrative & support | 2018 |
| Brightwell Aerials Ltd | Administrative & support | 2008 |
| Brill Church of England School | Education | 2013 |
| Brill Consulting Ltd | Professional & scientific | 2025 |
| Brill Consulting Services Ltd | Manufacturing | 2026 |
| Brill Sports & Social Club Limited | Hospitality | 2023 |
| Brilliant Carwash Ltd | Administrative & support | 2024 |
| Brine Engineering Solutions Ltd | Professional & scientific | 2014 |
| Brions Ltd | Financial services | 2024 |
| Britaniascheme Limited | Health & social care | 1987 |
| British Institute of Energy Economics (the) | Administrative & support | 1984 |
| Britpay Ltd | Administrative & support | 2010 |
| Brits Global Ltd | Information & communication | 2016 |
| Britt Infoz Ltd | Information & communication | 2019 |
| Brivo Ltd | Wholesale & retail | 2024 |
| Broad Runner Ltd | Transport & logistics | 2023 |
| Broadgate Creative Ltd | Professional & scientific | 2003 |
| Broadsword Hospitality | Professional & scientific | 2025 |
| Broadsword Hospitality Consulting | Professional & scientific | 2024 |
| Bromderry Ltd | Wholesale & retail | 2021 |
| Broncroft Holdings Limited | Financial services | 2000 |
| Brook Check Limited | Other services | 2025 |
| Brook Farm Commercial Limited | Real estate | 2022 |
| Brooks Auto Repair Ltd | Wholesale & retail | 2009 |
| Brooks Electrical Solutions Ltd | Construction | 2007 |
| Brooks Precision Engineering Holdings Ltd | Manufacturing | 2025 |
| Brooks Precision Engineering Limited | Manufacturing | 1989 |
| BROTHERS786 Ltd | Wholesale & retail | 2026 |
| Broughton Business Park (Bucks) Ltd | Wholesale & retail | 2016 |
| Broughton Business Park Holdings Limited | Real estate | 2016 |
| Broughton Farmhouse Limited | Households | 2024 |
| Broughton Properties (Bucks) Ltd | Real estate | 2017 |
| Brown & LEE, Aylesbury Ltd | Real estate | 2019 |
| Brown Antlers Limited | Professional & scientific | 2025 |
| Browne Information Consulting Limited | Information & communication | 1995 |
| Bruce Bros Ltd | Wholesale & retail | 2021 |
| Brunel Management Limited | Households | 2026 |
| Brush Party UK Limited | Arts & recreation | 2015 |
| Bscll Limited | Financial services | 2024 |
| BSH Contracts Limited | Wholesale & retail | 2007 |
| BT Trans Consultancy Ltd | Professional & scientific | 2023 |
| BT Vehicle Solutions Ltd | Wholesale & retail | 2026 |
| BT6 Resourcing Limited | Administrative & support | 2018 |
| BTL Combustion Services Ltd | Professional & scientific | 2019 |
| Bubble Businesses Ltd | Real estate | 2021 |