| Bonzai OOD Limited | Administrative & support | 2017 |
| Bookon Software Limited | Information & communication | 2025 |
| Boosey Automotive Ltd | Wholesale & retail | 2024 |
| Boqian LI Design Ltd | Professional & scientific | 2021 |
| Bore Ltd | Transport & logistics | 2019 |
| Borji Limited | Real estate | 2025 |
| Borough Green Cafe Ltd | Hospitality | 2023 |
| Boruzele Ltd | Wholesale & retail | 2013 |
| Bosch Glucksburg Perry Investments Limited | Financial services | 2012 |
| Bose Legacy Properties Ltd | Real estate | 2025 |
| Bosley Estates Limited | Real estate | 2016 |
| Boss CUT One Limited | Other services | 2026 |
| Bossfix Facilities Management Ltd. | Administrative & support | 2024 |
| Bound & Beyond Ltd | Wholesale & retail | 2025 |
| Bourne & Kemp Limited | Manufacturing | 1979 |
| Bournepark Facilities Ltd | Construction | 2024 |
| Bournes Funeral Service Ltd | Other services | 2009 |
| Boutique Construction Ltd | Construction | 2023 |
| Boutique Consultancy Ltd | Professional & scientific | 2019 |
| Boutique Property Developments (Aylesbury) Ltd | Real estate | 2018 |
| Boutique Property Ltd | Real estate | 2015 |
| Boutique Property South East Ltd | Real estate | 2023 |
| Boven Properties Limited | Real estate | 2026 |
| BOW Lane Bespoke Tailors Ltd | Wholesale & retail | 2023 |
| Bowen Strategy Ltd | Information & communication | 2025 |
| Bowers Property Developments Limited | Construction | 2023 |
| Bowwy Productions Ltd | Arts & recreation | 2021 |
| Box Bar & Bites Limited | Hospitality | 2025 |
| Box II Box Limited | Administrative & support | 2013 |
| Box Security Ltd | Construction | 1990 |
| Boxcentral Distribution Ltd | Hospitality | 2024 |
| Boxed Collectibles UK Ltd | Wholesale & retail | 2022 |
| Boyd&Boris Ltd | Extraterritorial | 2013 |
| Bphr Consultancy Limited | Professional & scientific | 2020 |
| Bpsr Limited | Wholesale & retail | 2023 |
| BR Whitechapel Limited | Real estate | 2019 |
| BR7 Cars Ltd | Wholesale & retail | 2025 |
| BR8 Construction Limited | Construction | 2004 |
| Braeside Developments Limited | Administrative & support | 2002 |
| Bragagnini Associates Property Solutions Limited | Administrative & support | 2007 |
| Brail Consulting Limited | Information & communication | 2015 |
| Brama Services Limited | Administrative & support | 2009 |
| Brambletree Wharf Ltd | Construction | 2018 |
| Brand HD Ltd | Professional & scientific | 2020 |
| Brand View Limited | Professional & scientific | 2024 |
| Brand Wasabi Ltd | Professional & scientific | 2024 |
| Brane Carpital Limited | Wholesale & retail | 2025 |
| Brasa-Lusitana Ltd | Hospitality | 2026 |
| Brasaa Corporation U.K Limited | Professional & scientific | 2008 |
| Braundton Property Services Ltd | Real estate | 2021 |
| Bravome Ltd | Wholesale & retail | 2026 |
| Brayhealth Limited | Administrative & support | 2019 |
| Brayland Electrical Ltd | Construction | 2021 |
| Breakfort Limited | Financial services | 2014 |
| Breaking Limit Security Limited | Administrative & support | 2019 |
| Bred Shed Limited | Hospitality | 2017 |
| Breezestone Ltd | Wholesale & retail | 2024 |
| Brefo Homes Ltd | Real estate | 2024 |
| Brent and Camden Osteopaths (Euro) Ltd | Health & social care | 2016 |
| Brent Mobile Fisheries Limited | Hospitality | 2020 |
| Bressenden Travel Company Limited | Administrative & support | 2009 |
| Bretts BR London Limited | Other services | 2018 |
| Bretts Business Recovery Limited | Professional & scientific | 2012 |
| Brewster Estates Limited | Construction | 1963 |
| BRF Limited | Construction | 2018 |
| BRG (Bexleyheath) Ltd | Other services | 2023 |
| BRH Installations Limited | Construction | 2007 |
| Brick and Sand Ltd | Construction | 2012 |
| Brickstock Ltd | Real estate | 2016 |
| Bridge Education International Limited | Education | 2025 |
| Bridge Education London Limited | Education | 2015 |
| Bridon Healthcare Furniture Limited | Wholesale & retail | 2006 |
| Brigade Halo Limited | Information & communication | 2025 |
| Bright Light Health Ltd | Health & social care | 2024 |
| Bright Logistic Services Limited | Transport & logistics | 2015 |
| Bright Properties Investment Ltd | Real estate | 2025 |
| Bright Sparks Communication Ltd | Professional & scientific | 2017 |
| Bright World Electrical Limited | Construction | 2017 |
| Brightlead Consulting Ltd | Professional & scientific | 2026 |
| Brightman Envirocel Limited | Construction | 2019 |
| Brightman Industries Limited | Manufacturing | 2001 |
| Brighton Rope Access Limited | Construction | 2006 |
| Bring Solutions Ltd | Construction | 2017 |
| Brisbaineunisexsalon Ltd | Other services | 2025 |
| Brise Fabrications Limited | Administrative & support | 2007 |
| Bristone Ltd | Administrative & support | 2015 |
| Brit Tuition Ltd | Education | 2016 |
| Britannia Academics Ltd | Education | 2023 |
| Britannia Court Residents Company Limited | Households | 2001 |
| Britannia Match Limited | Real estate | 1977 |
| Britannica Limited | Manufacturing | 2020 |
| Britasia Import Ltd | Wholesale & retail | 2024 |
| British-Kazakh Society | Other services | 2002 |
| Britledger Accounting Ltd | Professional & scientific | 2024 |
| Brittania Interior Contractors Ltd. | Construction | 2011 |
| Brittmade Limited | Wholesale & retail | 2021 |
| Brittrip Travel Service Ltd | Administrative & support | 2025 |
| Broadcast Systems Engineering Limited | Information & communication | 1990 |
| Broadreach Business Limited | Hospitality | 2001 |
| Broadreach Homeless Service | Hospitality | 2015 |