| Brockenhurst Management Company Limited | Households | 2010 |
| Brodersen Systems UK Ltd | Wholesale & retail | 2012 |
| Broken Island Films Limited | Information & communication | 2014 |
| Brokers International Ltd | Administrative & support | 2024 |
| Bromarpeak ITS Limited | Construction | 2019 |
| Bronte Industries, Ltd | Financial services | 2019 |
| Bronze Box Interactive Limited | Information & communication | 2022 |
| Brook House (Henley) RTM Company Limited | Households | 2025 |
| Brooke & Bloom London Limited | Wholesale & retail | 2026 |
| Brookers Hill Shinfield (M.C.) Limited | Households | 2018 |
| Brookland Transport Limited | Transport & logistics | 2010 |
| Brooks Renovations Ltd | Other services | 2023 |
| Brooks TM Solutions Ltd | Transport & logistics | 2019 |
| Brookside Solar Farm Limited | Energy | 2015 |
| Broomfield (Binfield) Management Company Limited | Households | 2006 |
| Broomwagon Cycle Tours Ltd | Administrative & support | 2019 |
| Bros Pets Limited | Wholesale & retail | 2021 |
| Brother Logistic Ltd | Transport & logistics | 2018 |
| Brothers Hairdressers Limited | Other services | 2020 |
| Brothers Office Solutions Limited | Wholesale & retail | 2012 |
| Brouard Pictures Ltd | Information & communication | 2023 |
| Brown Bear Productions Ltd | Information & communication | 2018 |
| Brown Family Holdings LLP | | 2021 |
| Brownes HR Consultancy Ltd | Other services | 2018 |
| Browning Solutions Limited | Information & communication | 2024 |
| Browning York Ltd | Professional & scientific | 2011 |
| Brownlow Lodge Management Company Limited | Households | 2004 |
| Browns Castle Inn Ltd | Hospitality | 2013 |
| Bruce Alpha Solutions Ltd | Information & communication | 2025 |
| Brujan Spedition Ltd | Construction | 2018 |
| Brunswick North Consultants Limited | Professional & scientific | 2022 |
| Brunswick Place Residents Limited | Households | 1990 |
| Brunswicks Limited | Transport & logistics | 2009 |
| Bryant Project Services Limited | Professional & scientific | 2002 |
| Bryngolwg Energy Storage Limited | Energy | 2023 |
| Brywel Associates Limited | Professional & scientific | 2001 |
| BS Brickwork Limited | Construction | 2018 |
| BS Master Properties Ltd | Real estate | 2023 |
| BS Masterbuilders Ltd | Construction | 2019 |
| BS Tasty BUN Limited | Hospitality | 2025 |
| Bsage Ltd | Information & communication | 2019 |
| BSB Construction and Design Ltd | Construction | 2019 |
| BSH London Advisers (2015) Limited | Administrative & support | 2015 |
| BSK Services Limited | Hospitality | 2024 |
| Bsky Holdings Limited | Financial services | 2021 |
| BSL Couriers Ltd | Transport & logistics | 2023 |
| BSL Plus Ltd | Education | 2024 |
| BSL Property Ltd | Real estate | 2024 |
| BSM Estates Limited | Real estate | 2018 |
| BSM Utilities Ltd | Construction | 2025 |
| Bsmr Limited | Other services | 2014 |
| BST Electrical Services Ltd | Construction | 2026 |
| BTB Building Services Ltd | Construction | 2024 |
| BTB Sky Builders Limited | Construction | 2024 |
| BTC Global Limited | Professional & scientific | 2010 |
| BTC Solutions Limited | Information & communication | 2007 |
| BTD Consulting Ltd | Professional & scientific | 2015 |
| Btfc Ltd | Arts & recreation | 2025 |
| Btqa Partners Limited | Professional & scientific | 2011 |
| BTS IT Ltd | Information & communication | 2016 |
| Bubble Brick Properties Ltd | Real estate | 2020 |
| Bubble T Ltd | Hospitality | 2026 |
| Bucas Electrical Services Ltd | Construction | 2024 |
| Buccaneer Bidco Limited | Financial services | 2018 |
| Buccaneer Holdco Limited | Financial services | 2018 |
| Buccaneer Intermediate Holdco Limited | Financial services | 2018 |
| Buccaneer Midco Limited | Financial services | 2018 |
| Buccaneer Subco Limited | Financial services | 2018 |
| Buchila Limited | Construction | 2018 |
| Buckenham Consultancy Ltd | Professional & scientific | 2014 |
| Buckland Civil Engineering Ltd | Financial services | 2012 |
| Bucklebury Holdings Limited | Construction | 2022 |
| Bucklebury Investments Limited | Construction | 2020 |
| Bucklebury Management Limited | Financial services | 2021 |
| Bucklebury Merchants Limited | Professional & scientific | 2023 |
| Bucklebury Place (Management) Limited | Households | 1986 |
| Bucklebury Projects Limited | Real estate | 2019 |
| Bucklebury Trading Company Limited | Wholesale & retail | 2013 |
| Bucklers Coffee Ltd | Hospitality | 2025 |
| Buckley Stunt & Wireworks Ltd | Arts & recreation | 2019 |
| Bucknell Holdings Limited | Real estate | 1983 |
| Buddha DAL UK CIC | Education | 2019 |
| Buddha EYE Ltd | Wholesale & retail | 2014 |
| Buddha Technologies Limited | Information & communication | 2016 |
| Buds Group Ltd | Real estate | 2015 |
| Bugnappers Limited | Information & communication | 2026 |
| Build by Just Limegrass Limited | Administrative & support | 2021 |
| Build IT Click by Click Group Ltd | Wholesale & retail | 2019 |
| Build My Care Limited | Administrative & support | 2022 |
| Build Rapport Limited | Administrative & support | 2022 |
| Buildcore Limited | Construction | 2018 |
| Builders Beams 4U Ltd | Manufacturing | 2016 |
| Builders Firstchoice Ltd | Wholesale & retail | 2020 |
| Buildguru Ltd | Construction | 2013 |
| Building 7 Harbourside Management Company Limited | Real estate | 2005 |
| Building Bree Ltd | Health & social care | 2025 |
| Building Control Solution Services Ltd | Professional & scientific | 2018 |
| Building Estimates Ltd | Other services | 2023 |
| Building Materials Logistics Ltd | Transport & logistics | 2011 |
| Building Materials Nationwide Limited | Wholesale & retail | 2013 |