| Body Mechanics Remedial Ltd | Health & social care | 2013 |
| Body Mind Health Works Ltd | Health & social care | 2019 |
| Bogdan-Ciprian Macovei Ltd | Construction | 2016 |
| Boisen Products Limited | Transport & logistics | 2025 |
| Bold AS Love Ltd | Information & communication | 2021 |
| Bolico Ltd | Construction | 2023 |
| Bollin Properties Ltd | Real estate | 2021 |
| Bollingtons Properties Ltd | Real estate | 2021 |
| Bombay Central Ltd | Hospitality | 2015 |
| Bond House Advisors Unlimited | Administrative & support | 2010 |
| Bondar Ltd | Construction | 2018 |
| Bondi UK Investments and Development Limited | Real estate | 2013 |
| Bontina Properties Limited | Construction | 2022 |
| Bookkeeping Support Limited | Professional & scientific | 2007 |
| Boost Bar Ltd | Manufacturing | 2024 |
| Booze Delivery Limited | Wholesale & retail | 2019 |
| Boring Investment Company Ltd | Financial services | 2019 |
| Born to Swim Ltd | Health & social care | 2005 |
| Botnari Construction Ltd | Construction | 2025 |
| Boudica Inns Limited | Hospitality | 2004 |
| Bounce Bhangra Ltd. | Arts & recreation | 2017 |
| Bounce Communications Ltd. | Professional & scientific | 2018 |
| Bourne END Moorings Ltd | Real estate | 2019 |
| Bourne Vale Consulting Limited | Administrative & support | 2014 |
| Boxfort Limited | Extraterritorial | 2018 |
| Boys Own Productions Ltd | Wholesale & retail | 2016 |
| Boytongate Limited | Arts & recreation | 1983 |
| BP Construction Services Ltd | Construction | 2020 |
| BPG General Limited | Wholesale & retail | 2009 |
| Bpharm Limited | Health & social care | 2002 |
| BPS Autocare Limited | Administrative & support | 2017 |
| BR Developers Ltd | Construction | 2017 |
| Braden Developments Limited | Real estate | 2010 |
| Braids Barbers Limited | Other services | 2014 |
| Brandt Asian Art Limited | Wholesale & retail | 2008 |
| Brasserie Lumiere Limited | Hospitality | 2024 |
| Bravevision Limited | Administrative & support | 1998 |
| Brenor Limited | Construction | 2015 |
| Brent House Development Limited | Real estate | 2015 |
| Brentbrooks Ltd | Real estate | 2026 |
| Brentpark Limited | Real estate | 2004 |
| Brentpark(Harrow) Limited | Real estate | 2010 |
| Brentwood Gate Ltd | Real estate | 2025 |
| Brewers Imports Limited | Transport & logistics | 1993 |
| BRG Investments Limited | Real estate | 2025 |
| Brian Shoes Limited | Information & communication | 2024 |
| Briars/Halfacre Management Company Limited(The) | Real estate | 1983 |
| Brick Art Constructions Ltd | Construction | 2021 |
| Brick Kiln Holding Limited | Construction | 2024 |
| Brickstone & Flint Limited | Construction | 2014 |
| Brickwork Tools Ltd | Manufacturing | 2019 |
| Brickworks Engineered Masonry Limited | Construction | 2003 |
| Bridge London Capital Limited | Real estate | 2023 |
| Bridges Therapy Ltd | Health & social care | 2019 |
| Bridgeway Digital Design & Animations Ltd | Wholesale & retail | 2020 |
| Bridgewood Builders Limited | Construction | 1997 |
| Bright Green Promotions Limited | Professional & scientific | 2011 |
| Bright Little Stars Stanmore Limited | Education | 2016 |
| Bright Start Day Care Limited | Education | 2005 |
| Brighthire Education Ltd | Administrative & support | 2025 |
| Brij Investment Limited | Real estate | 2024 |
| Brindley Court RTM Limited | Real estate | 2009 |
| Brinkley Management Company Ltd | Households | 2019 |
| Briteuro Express Ltd | Transport & logistics | 2024 |
| British Hernia Centres Ltd | Extraterritorial | 1994 |
| Britro Consulting Ltd | Professional & scientific | 2020 |
| Brittonum Limited | Wholesale & retail | 2012 |
| Brjo Medico Ltd | Health & social care | 2025 |
| Brjo Trades Ltd | Financial services | 2025 |
| BRL Invest Ltd | Construction | 2019 |
| BRO Builders Group Ltd | Construction | 2019 |
| Broad Oak Finance Limited | Financial services | 1988 |
| Broadcroft Properties Limited | Real estate | 2019 |
| Broadfields 2020 Limited | Real estate | 2020 |
| Broadfields United Football Club Limited | Arts & recreation | 2024 |
| Broadhurst Management Ltd | Real estate | 2022 |
| Broadway Fashions Limited | Wholesale & retail | 2005 |
| Brockley Developments Limited | Real estate | 2016 |
| Brockley Finance Limited | Wholesale & retail | 1987 |
| Brockley Hill House Limited | Real estate | 2003 |
| Brockwell Gate Management Company Limited | Households | 1999 |
| Bronzdale Limited | Administrative & support | 2003 |
| Bronzehunt Limited | Construction | 1983 |
| Bronzerf UK Ltd | Real estate | 2023 |
| Brook Street Property Limited | Real estate | 2017 |
| Brookfield Surveys Limited | Professional & scientific | 2025 |
| Brookleigh Developments Ltd | Construction | 2026 |
| Brooklink Limited | Professional & scientific | 2001 |
| Browserie London Ltd | Other services | 2025 |
| Bruder Automation Limited | Professional & scientific | 2025 |
| Bruno Singh Investments Ltd | Professional & scientific | 2021 |
| Bruton Internet Limited | Information & communication | 2009 |
| Bryte Smile Limited | Health & social care | 2015 |
| BS Builders London Limited | Construction | 2023 |
| BS Food Supplies Limited | Wholesale & retail | 2015 |
| BS Property Limited | Construction | 2016 |
| BSH Limited | Professional & scientific | 2015 |
| BSK Mechanical Limited | Construction | 2024 |
| Bslph Limited | Hospitality | 2022 |
| Bspi 1 Limited | Real estate | 2023 |