| Blue for YOU Properties Limited | Real estate | 2020 |
| Blue Harbour Estates Holdings Limited | Financial services | 2022 |
| Blue Harbour Estates Investments Limited | Real estate | 2022 |
| Blue Harbour Estates Services Limited | Wholesale & retail | 2022 |
| Blue Octopus Consulting Limited | Professional & scientific | 2008 |
| Blue Rise Consultants Limited | Professional & scientific | 2025 |
| Bluebell Cars Bidco Limited | Financial services | 2022 |
| Bluebell Cars Midco Limited | Financial services | 2022 |
| Bluebell Cars Topco Limited | Financial services | 2022 |
| Bluebell Practice Management Limited | Administrative & support | 2015 |
| Blueheaven Property Limited | Real estate | 2026 |
| Bluesky Tools Co., Ltd | Manufacturing | 2019 |
| Bluestocking Consult Ltd | Information & communication | 2016 |
| Blundz Service Limited | Professional & scientific | 2019 |
| Blyth Solar Limited | Construction | 2025 |
| BM Carpentry Limited | Manufacturing | 2012 |
| BM Services Private Limited | Wholesale & retail | 2021 |
| BM14 Finance Ltd | Financial services | 2026 |
| BMS Install Ltd | Construction | 2022 |
| BNR Dining Ltd | Hospitality | 2023 |
| BO & S Logistics Ltd | Transport & logistics | 2017 |
| BO Malda Glazing Ltd | Construction | 2020 |
| Boas Advisors Ltd | Professional & scientific | 2021 |
| BOB Connections Ltd | Other services | 2025 |
| BOB King Creative Limited | Professional & scientific | 2015 |
| Bobaiocca Ltd | Hospitality | 2022 |
| Bode Services Limited | Construction | 2025 |
| Bodman Construction and Consultancy Group Limited | Professional & scientific | 2026 |
| Body Buddies Limited | Information & communication | 2014 |
| Body Fashion Group Limited | Wholesale & retail | 2024 |
| Body Temple Gym Ltd | Arts & recreation | 2015 |
| Boiler Care Kent Ltd | Other services | 2016 |
| Boiler Tech Heating Services Ltd | Construction | 2015 |
| Boiler Zone Installations Ltd | Construction | 2025 |
| Bojlanto Ventures Limited | Construction | 2017 |
| Bola Investments Limited | Real estate | 2018 |
| Bold Hold Ltd | Other services | 2020 |
| Bollywood Box Ltd | Hospitality | 2026 |
| BON BON (Medway) Limited | Wholesale & retail | 2012 |
| BON Grill Limited | Hospitality | 2016 |
| Bona Fides International Limited | Wholesale & retail | 2022 |
| Bonorum Properties Limited | Real estate | 2018 |
| Book a Bar Ltd | Hospitality | 2020 |
| Boomlak Limited | Extraterritorial | 2023 |
| Boora House Ltd | Real estate | 2023 |
| Booth White Asset Management Limited | Financial services | 2023 |
| Booth White Ltd | Administrative & support | 2014 |
| Boredom Limited | Information & communication | 2025 |
| Born Strong Ltd | Wholesale & retail | 2024 |
| Bosa Enterprise Limited | Health & social care | 2012 |
| Bosite Technology Industrial Limited | Extraterritorial | 2019 |
| Boss Glass Co., Limited | Extraterritorial | 2015 |
| Boss MAN Taxis Ltd | Transport & logistics | 2024 |
| Botanical Beauty Limited | Other services | 2001 |
| Boundwell Ltd | Real estate | 2000 |
| Bourton Consulting Ltd | Professional & scientific | 2025 |
| Bourton Fencing Limited | Manufacturing | 1975 |
| BOW Mellow Ltd | Manufacturing | 2021 |
| Bowles Asset Management Limited | Real estate | 2025 |
| Bowman Transport Limited | Transport & logistics | 2019 |
| Bowring Ltd | Education | 2024 |
| Box-Ecom Ltd | Manufacturing | 2024 |
| Boychu Limited | Health & social care | 2023 |
| Boyu Holding Group Ltd | Wholesale & retail | 2021 |
| Bradfield Property Portfolio Limited | Real estate | 2014 |
| Brady Ltd | Administrative & support | 2025 |
| Brainy Marketings Ltd | Information & communication | 2025 |
| Brandywell Custom and Classics LLP | | 2023 |
| Brawd Carpentry Ltd | Construction | 2017 |
| Bredhurst Car Sales Limited | Wholesale & retail | 2017 |
| Bredhurst Garages Limited | Wholesale & retail | 1970 |
| Bredhurst Holdings Limited | Real estate | 2015 |
| Bredhurst Properties Limited | Administrative & support | 1998 |
| Breeze & Bloom Wellness by Victoria Ltd | Other services | 2025 |
| Breeze Hire UK Limited | Administrative & support | 2018 |
| Brenchley Waterside Management Company Limited | Households | 2005 |
| Brennan Communications Limited | Information & communication | 2011 |
| BRG Rail Ltd | Professional & scientific | 2023 |
| Brick and Mortar Estates Limited | Real estate | 2021 |
| Brick by Brick Property Services Ltd | Construction | 2017 |
| Bricksbury Homes Ltd | Real estate | 2021 |
| Brides of Dorset Ltd | Wholesale & retail | 2022 |
| Bridging the GAP Kent Ltd | Hospitality | 2025 |
| Briel Trans Limited | Transport & logistics | 2020 |
| Bright Future Education Limited | Education | 2022 |
| Bright Tools Limited | Administrative & support | 2010 |
| Brightsky Collective Ltd | Education | 2018 |
| Brilliant Start Corp Ltd | Manufacturing | 2022 |
| Brillon Group Limited | Public administration | 2021 |
| Brilwon Ltd | Wholesale & retail | 2023 |
| Brinsley Build Ltd | Construction | 2023 |
| Brinvent Company Ltd | Wholesale & retail | 2018 |
| Brioche Ltd | Manufacturing | 2025 |
| Britanian Ltd | Administrative & support | 2017 |
| Britannia Bay Development Corporation Ltd | Construction | 2022 |
| Britannia Online Retail Ltd | Wholesale & retail | 2020 |
| Britannia Property Maintenance Ltd | Construction | 2022 |
| Britestone Capital Limited | Mining & quarrying | 2016 |
| Broadcastwired.Com Limited | Information & communication | 1995 |
| Broadway Care Limited | Public administration | 2022 |