| Brownlee Fitness Limited | Arts & recreation | 2020 |
| Brownlee Racing Ltd | Arts & recreation | 2024 |
| Brows & Beauty Lounge Ltd | Other services | 2023 |
| Brundall Meadows (Brundall) Management Company Limited | Households | 2026 |
| Bruno Physical Rehabilitation Community CIC | Education | 2025 |
| Bruno Physical Rehabilitation Ltd | Health & social care | 2025 |
| Brunswick Electrical Services Limited | Manufacturing | 2009 |
| Brute Force Limited | Real estate | 1995 |
| Bryanperera Ltd | Information & communication | 2025 |
| Bryony Page Limited | Arts & recreation | 2019 |
| BSA Group Legal Services Ltd | Professional & scientific | 2021 |
| BSC Learning CIC | Education | 2025 |
| BSC Multicultural Services | Administrative & support | 2004 |
| Bsmuk Ltd | Health & social care | 2020 |
| BSP TEX Ltd | Manufacturing | 1923 |
| BSS Stores Ltd | Wholesale & retail | 2020 |
| Bssaa (2018) Limited | Health & social care | 2018 |
| Bssh Traders Ltd | Wholesale & retail | 2025 |
| BT Global Ltd | Wholesale & retail | 2024 |
| BTA Consultants Ltd | Information & communication | 2019 |
| BTI Construction Ltd | Construction | 2025 |
| BTL Scaffolding Limited | Construction | 2026 |
| BTS Cards Ltd | Wholesale & retail | 2024 |
| Bubble Snaps Ltd | Arts & recreation | 2021 |
| Bucharest 1 Ltd | Transport & logistics | 2020 |
| Buck Estates ST Johns RD Ltd | Real estate | 2022 |
| Buck Estates Beckside Ltd | Construction | 2022 |
| Buck Estates Cotswold Ltd | Real estate | 2022 |
| Buck Estates Holdings Limited | Financial services | 2021 |
| Buck Estates Limited | Administrative & support | 2005 |
| Buck Estates Linden Road Ltd | Financial services | 2023 |
| Buckingham Recruitment Limited | Administrative & support | 2010 |
| Bucklands Security Ltd | Administrative & support | 2023 |
| Buckle & Goldsmith Investments Limited | Real estate | 2016 |
| Buckle Consultancy Ltd | Information & communication | 2023 |
| Bucklesham Associates Ltd | Professional & scientific | 2011 |
| Buddyinca Ltd | Construction | 2025 |
| Buff LAB Ltd | Wholesale & retail | 2025 |
| Bugajozsi Ltd | Transport & logistics | 2024 |
| Buggle Business Centre Limited | Real estate | 2007 |
| Bughlani & Co Ltd | Wholesale & retail | 2024 |
| Buikeme Global ENT Ltd | Wholesale & retail | 2024 |
| Build Bright Consulting Ltd | Professional & scientific | 2024 |
| Build Extend and Improve Ltd | Construction | 2026 |
| BUILD360 Ltd | Construction | 2019 |
| Buildcandy Group Limited | Construction | 2022 |
| Building Capability Limited | Information & communication | 2023 |
| Building IO Solutions Ltd | Professional & scientific | 2016 |
| Building Maintenance Direct Ltd | Administrative & support | 2020 |
| Building Refurbishments and Civils Ltd | Construction | 2010 |
| Building Send Castles Ltd | Education | 2025 |
| Building USE Studies Limited | Professional & scientific | 1980 |
| Buildspan Limited | Wholesale & retail | 2024 |
| Buildwell Construction (East Anglia) Limited | Construction | 2003 |
| Buildworth Limited | Real estate | 2020 |
| Built 2 WIN Ltd | Wholesale & retail | 2018 |
| Bul-Transport Ltd | Transport & logistics | 2021 |
| Bull Run Logistics Ltd | Transport & logistics | 2021 |
| Bulwark Fire Protection Ltd | Public administration | 2022 |
| Bumble & Bunny Limited | Wholesale & retail | 2017 |
| BUN N Run Limited | Hospitality | 2020 |
| Bungay Property Management Ltd | Real estate | 2012 |
| Bunker-Safe Limited | Construction | 2025 |
| Bunny OWL Games Limited | Information & communication | 2026 |
| Bunny Transport Limited | Construction | 2014 |
| Buoyant Property Ltd | Real estate | 2016 |
| Bupalo Clothing Ltd | Wholesale & retail | 2026 |
| Burard Limited | Hospitality | 2021 |
| Burch Electrical Services Ltd | Construction | 2023 |
| Burchgreen Homes Limited | Real estate | 1967 |
| Burgess & Fitch Ltd | Construction | 2024 |
| Burgess and Simpson Property Limited | Real estate | 2017 |
| Burgess Build Group Ltd | Construction | 2022 |
| Burlingham House Limited | Households | 1987 |
| Burnt Mill Brewery Ltd | Manufacturing | 2016 |
| Burnt Mill Taproom BSE Ltd | Hospitality | 2025 |
| Burnt Wood Limited | Agriculture & fishing | 2017 |
| Burrell Capital Group Ltd | Financial services | 2026 |
| Burrell Road Properties Limited | Construction | 2016 |
| Burrell's Building Services Ltd | Construction | 2025 |
| Burrows Holdings Limited | Extraterritorial | 1985 |
| Burt the Binman Limited | Information & communication | 2015 |
| Burton Green Limited | Administrative & support | 2025 |
| Burton Marine & Engineering Limited | Professional & scientific | 1997 |
| Burunciuc Ltd | Construction | 2025 |
| Bury ST Refills Ltd | Wholesale & retail | 2025 |
| BUS' Industrial Tools Limited | Wholesale & retail | 2014 |
| BUS' Real Estate UK Limited | Real estate | 2017 |
| Bushey Park Management Company Limited | Extraterritorial | 2009 |
| Bushido Limited | Hospitality | 2024 |
| Busimum Ltd | Administrative & support | 2025 |
| Business & Legal Ltd | Professional & scientific | 2014 |
| Business & Legal Solutions Ltd | Professional & scientific | 2016 |
| Business Account Ltd. | Professional & scientific | 2023 |
| Business Critical Limited | Professional & scientific | 2009 |
| Business Enhancement Solution Limited | Administrative & support | 2005 |
| Business Happy Limited | Wholesale & retail | 2022 |
| Business Needs Limited | Information & communication | 2025 |
| Business School England Limited | Education | 2020 |
| BUSINESS2 Ltd | Professional & scientific | 2020 |