| Bodybycathy Ltd | Administrative & support | 2013 |
| Bodysculptorben Ltd. | Arts & recreation | 2015 |
| Bollin Capital Ltd | Financial services | 2015 |
| Bond Consultancy Limited | Administrative & support | 2025 |
| Bonini Advice London Limited | Financial services | 2026 |
| Boom Licensing Limited | Professional & scientific | 2012 |
| Border Mews Limited | Real estate | 2010 |
| Bosss (UK) Limited | Education | 2002 |
| Boundary Health Limited | Health & social care | 2022 |
| Boundary House Limited | Households | 1966 |
| Bourne Books Limited | Wholesale & retail | 2020 |
| Bourne END Post Limited | Transport & logistics | 2021 |
| Bower-Bird Limited | Administrative & support | 2024 |
| Bowstead Limited | Real estate | 2017 |
| Box Marketing Limited | Administrative & support | 2003 |
| BR Data Limited | Information & communication | 2012 |
| BR Deane Consulting Limited | Administrative & support | 2015 |
| BR Network Limited | Information & communication | 1999 |
| Bradenham Partners LLP | | 2009 |
| Braemar Freehold Limited | Real estate | 2014 |
| Braid Court Residents Association Limited | Households | 1972 |
| Braid Gardens Management Company Limited | Households | 2002 |
| Bramar Properties Limited | Other services | 1983 |
| Brambles Animal Encounters Limited | Extraterritorial | 2024 |
| Brambles Management Services Limited | Health & social care | 2024 |
| Brand-Consultants Ltd | Financial services | 2023 |
| Brandle's Amusements Limited | Arts & recreation | 2022 |
| Brandle's Property Limited | Real estate | 2022 |
| Brandon GTM Consulting Ltd | Information & communication | 2023 |
| Bray Sound Limited | Information & communication | 2009 |
| Break Point Limited | Wholesale & retail | 2004 |
| Breakthrough Intensives Ltd | Health & social care | 2025 |
| Breakthru Solutions Ltd | Wholesale & retail | 2022 |
| Breathe Outside C.I.C. | Health & social care | 2021 |
| Breezee Holdings Limited | Information & communication | 2023 |
| Breezee Technology Limited | Information & communication | 2022 |
| Brendleton Ltd | Construction | 2025 |
| Brew GAS & Heating Ltd. | Construction | 2021 |
| Brick Block Contractors Ltd | Construction | 2025 |
| Brick by Brick Clothing Limited | Manufacturing | 2024 |
| Brick Space Limited | Manufacturing | 2023 |
| Bridge Cottage Limited | Health & social care | 2010 |
| Bridge House Financial (Bucks) Ltd | Real estate | 2013 |
| Bridges Worldwide (UK) Limited | Transport & logistics | 1999 |
| Bridges Worldwide PLC | Transport & logistics | 1989 |
| Bright Communications Limited | Information & communication | 2022 |
| Brightnest Property Ltd | Hospitality | 2026 |
| Brightstay Property Ltd | Hospitality | 2025 |
| Brindisa Kitchens Limited | Hospitality | 2003 |
| Bristol Psychology Clinic Ltd | Health & social care | 2020 |
| Britasia Film Finance Limited | Information & communication | 2024 |
| Britten Partners UK Limited | Professional & scientific | 2006 |
| Broadcast Journalism Training Council | Information & communication | 1996 |
| Brooks & Bowers Limited | Professional & scientific | 2024 |
| Brookson (5583K) Limited | Administrative & support | 2007 |
| BROTHER804 Ltd | Wholesale & retail | 2025 |
| Brownstone Investment Partners Limited | Real estate | 2018 |
| BRS Data Science Ltd | Information & communication | 2022 |
| Bruce Brown Creative Limited | Professional & scientific | 2018 |
| Brunch & Nunch Ltd | Hospitality | 2025 |
| Brutto Limited | Hospitality | 2021 |
| Brycheiniog Limited | Professional & scientific | 2009 |
| BS Fitness Ltd | Other services | 2016 |
| BSG Financial Solutions Limited | Administrative & support | 2004 |
| BSG Topco Limited | Financial services | 2021 |
| Buchanan Computing Limited | Information & communication | 1996 |
| Buchanan Technologies Limited | Information & communication | 2022 |
| Bucks Care Ltd | Health & social care | 2024 |
| Bucks Estates Limited | Real estate | 2021 |
| Bucks Mobile Tyres Ltd | Manufacturing | 2025 |
| Bucks Plumbing Services Limited | Construction | 2020 |
| Bucks Psychiatry Ltd | Health & social care | 2015 |
| Bulldog Club (Incorporated) | Other services | 1894 |
| Bulstrode Ventures Limited | Professional & scientific | 2025 |
| Bulstrode Way Management Company Limited | Households | 2011 |
| Buntingford Healthcare Limited | Wholesale & retail | 2011 |
| Burgess Wood LLP | | 2013 |
| Burning Blue Performance Limited | Professional & scientific | 2015 |
| Burton Lights Ltd | Construction | 2022 |
| Business Watts Ltd | Wholesale & retail | 2025 |
| Butterfly & Wolf Limited | Other services | 2024 |
| Button Ventures Ltd | Real estate | 2021 |
| Buycombi Ltd | Wholesale & retail | 2003 |
| Bwoywonder Kids Limited | Manufacturing | 2018 |
| Bysolum Ltd | Wholesale & retail | 2026 |
| Byzanti Drinks Limited | Manufacturing | 2024 |
| C & L Fabrics Ltd | Wholesale & retail | 2021 |
| C&H Designs Ltd | Manufacturing | 2023 |
| C&L Assets Ltd | Real estate | 2005 |
| C&L Creations Ltd | Real estate | 2023 |
| C&L Trust Ltd | Real estate | 2026 |
| C&S Windows Limited | Other services | 2003 |
| C.R.M. Carpentry & Joinery Limited | Construction | 2005 |
| Caaid Ltd | Information & communication | 2019 |
| CAB Office Services Ltd | Administrative & support | 2013 |
| Caddo Limited | Information & communication | 2018 |
| Cadencia Consultancy Limited | Professional & scientific | 2013 |
| Caesar Clinical Solutions Limited | Health & social care | 2020 |
| Caesar Medicare Limited | Wholesale & retail | 2021 |
| Calcot Residents Association Limited | Households | 1987 |