| Blue Manta Holdings Limited | Real estate | 2022 |
| Blue Oak Advisory Limited | Other services | 2019 |
| Blue Rock Property Investments Ltd | Real estate | 2020 |
| Blue Sky Roofing Ltd | Construction | 2025 |
| Blue Skyline Engineering Limited | Manufacturing | 2024 |
| Blue Water Consulting Limited | Information & communication | 1999 |
| Bluebabel Limited | Professional & scientific | 2008 |
| Bluebrix PVT Ltd | Real estate | 2022 |
| Blueprint Builders Manufacturing Limited | Construction | 2024 |
| Blueprint Surveys Ltd | Professional & scientific | 2007 |
| BM Global Services Limited | Administrative & support | 2018 |
| BM Prime Construction Company Ltd | Construction | 2025 |
| BNT Beauty Ltd | Other services | 2024 |
| Board Climbing Ltd | Wholesale & retail | 2026 |
| Boba Journey Ltd | Wholesale & retail | 2024 |
| Bobo Experiences Ltd | Wholesale & retail | 2022 |
| Bobz Building and Landscaping Ltd | Professional & scientific | 2023 |
| BOC Construction Services Ltd | Construction | 2022 |
| Body Concepts UK Limited | Other services | 2004 |
| Boff Consulting Ltd | Professional & scientific | 2023 |
| Boffin Films Ltd | Information & communication | 2020 |
| Boglarka Ltd | Information & communication | 2025 |
| Bonesgate Consulting Limited | Professional & scientific | 2022 |
| Bonfire Video Ltd. | Information & communication | 2016 |
| Bookcetera Ltd | Wholesale & retail | 2018 |
| Booming Marvelous Limited | Professional & scientific | 2014 |
| Bordelaise Maple Ltd | Hospitality | 2025 |
| Bornman Property Investment Ltd | Real estate | 2023 |
| Bourne Services Limited | Construction | 2006 |
| Bowman Collectables Limited | Wholesale & retail | 2026 |
| Bowman Residential Ltd | Real estate | 2025 |
| Bowstar Properties Limited | Real estate | 1991 |
| BP Software Consulting Ltd | Information & communication | 2015 |
| Bptolworth Ltd | Hospitality | 2025 |
| Brae Court Freehold Limited | Real estate | 2004 |
| Brainbridge Tutors Ltd | Education | 2026 |
| Bramley Mansions Limited | Real estate | 2025 |
| Bramley Mansions Residents Company Ltd | Real estate | 2003 |
| Bramshott Lodge RTM Company Ltd | Households | 2020 |
| Brand Arkade Limited | Professional & scientific | 2009 |
| Brand Narrative Limited | Professional & scientific | 2015 |
| Branded Europe Limited | Wholesale & retail | 2015 |
| Brandon Groundwoks & Utilities Ltd | Construction | 2025 |
| Brandon Groundworks and Steelworks Ltd | Construction | 2025 |
| Brandon Groundworks Ltd | Construction | 2016 |
| Brayer Design Ltd | Professional & scientific | 2024 |
| Brazilian Butchery Acougue E Mercearia Ltd | Wholesale & retail | 2018 |
| BRC Industrial Roofing Specialists Limited | Construction | 1972 |
| Breath Engineering Ltd | Professional & scientific | 2025 |
| Bretwalda Books Limited | Information & communication | 2011 |
| Brickdale Ltd | Real estate | 2020 |
| Bridge Governance Limited | Extraterritorial | 2025 |
| Bridge IT Property Ltd | Real estate | 2023 |
| Bridge Safety Pro Ltd | Health & social care | 2025 |
| Bright Stars Day Nursery Limited | Health & social care | 2012 |
| Bright Stars Property Management Limited | Administrative & support | 2017 |
| Brighter Future Consulting Limited | Professional & scientific | 2009 |
| Brightnet UK Limited | Information & communication | 2008 |
| Brightpath Media Ltd | Information & communication | 2025 |
| Brightwin Engineering Ltd | Construction | 2021 |
| Briony Gittins ESG Communications Ltd | Professional & scientific | 2022 |
| Brit Moving Service Ltd | Transport & logistics | 2025 |
| Britafrique Limited | Information & communication | 2007 |
| British Co-Masonic Trust Limited | Other services | 1921 |
| British Concert Orchestra (Founded 1945) Limited (the) | Arts & recreation | 1967 |
| Britlux Limited | Wholesale & retail | 2026 |
| Britsphere Ltd | Wholesale & retail | 2025 |
| Broadway Food Mart Ltd | Wholesale & retail | 2020 |
| Brollo Consulting Limited | Professional & scientific | 2023 |
| Bron LAR LLP | | 2021 |
| Bronco Creative Ltd. | Professional & scientific | 2015 |
| Brook House Associations Limited | Real estate | 2014 |
| Brook Property Consulting Limited | Professional & scientific | 2016 |
| Brooker Property Investments (UK) Limited | Real estate | 2020 |
| Brookgrove Limited | Real estate | 1982 |
| Broom Close Limited | Households | 1958 |
| Bru-Group Limited | Wholesale & retail | 2016 |
| Bruce Duncan Limited | Administrative & support | 2012 |
| Brunswick Surgery Ltd | Health & social care | 2024 |
| Bryan&Ben Limited | Transport & logistics | 2016 |
| Bryanston Partners Gold Limited | Financial services | 2025 |
| Bryanston Partners Ltd | Professional & scientific | 2020 |
| BSA UK Association | Other services | 2012 |
| Bsdb Limited | Professional & scientific | 2008 |
| BSO Building Services Ltd | Construction | 2025 |
| Bspokeevents Limited | Administrative & support | 2015 |
| Bubblegum Search Limited | Professional & scientific | 2016 |
| Buckingham (Alpha Wharf) Limited | Construction | 2011 |
| Buckingham (Malling Brooks) Limited | Real estate | 2021 |
| Buckingham Asset Management Limited | Real estate | 2019 |
| Buckingham Homes (Chapel Quarter) Limited | Real estate | 2018 |
| Buckingham Homes Limited | Real estate | 2014 |
| Buddhi Ltd | Professional & scientific | 2024 |
| Buddy Player Ltd | Arts & recreation | 2019 |
| Bugs Bisou Limited | Manufacturing | 2023 |
| Build IT Right Group Limited | Construction | 2018 |
| Build Visualise Design Ltd | Construction | 2023 |
| Build-It Rite Limited | Construction | 2011 |
| Building Home Engineer Ltd | Construction | 2025 |
| Buildlabuk Ltd | Administrative & support | 2023 |