| Blast ! Films Limited | Information & communication | 1994 |
| Blast! Films-Hunger Limited | Information & communication | 2007 |
| Blast! Films-One Day Limited | Information & communication | 2008 |
| BLB Bigmama Limited | Professional & scientific | 2008 |
| Bleepbleeps Limited | Wholesale & retail | 2014 |
| Blinding Windows Ltd | Manufacturing | 2023 |
| Bloemfontein Productions Ltd | Information & communication | 2025 |
| Blossom Way Ltd | Real estate | 2025 |
| Blue Gold Ltd | Real estate | 2021 |
| Blue Iris Limited | Information & communication | 2016 |
| Blue Line Commissioning Ltd | Water & waste | 2026 |
| Blue Mint Limited | Administrative & support | 2014 |
| Blue Sea Investments Ltd | Real estate | 2019 |
| Bluecrest Healthcare Limited | Wholesale & retail | 2011 |
| Blueland Limited | Information & communication | 2016 |
| Bluemaster Construction Ltd | Construction | 2025 |
| Blueprint PS Ltd | Construction | 2025 |
| Blueslon Limited | Professional & scientific | 2011 |
| Bluestones Marketing Management & IT Solutions Limited | Professional & scientific | 2012 |
| Bluetec Chauffeurs Ltd | Administrative & support | 2016 |
| Blueworld Consulting Ltd | Information & communication | 2013 |
| BOB & Henry Ltd | Real estate | 2024 |
| Bobby's Props Limited | Information & communication | 2005 |
| Bodyrax Ltd | Manufacturing | 2026 |
| Boforomoc Ltd | Other services | 2019 |
| Boiled EGG Salad Limited | Wholesale & retail | 2026 |
| Boilers, Kitchens and Bathrooms Limited | Construction | 2022 |
| Bolder Academy Trust | Education | 2014 |
| Bolero Holdings (UK) Limited | Financial services | 2019 |
| BON & Co Limited | Construction | 2025 |
| Bond Flooring Ltd | Extraterritorial | 2013 |
| Bone & Joint Practice Limited | Health & social care | 2020 |
| Bonhaus London Limited | Construction | 2025 |
| Bonnick Works Limited | Water & waste | 2025 |
| Booking Official Limited | Hospitality | 2025 |
| Books & Beans Ltd | Wholesale & retail | 2026 |
| Booma Media Limited | Information & communication | 2018 |
| Boraj Plastering Ltd | Construction | 2026 |
| Born Again Productions PVT Ltd | Information & communication | 2022 |
| Borough Property Co Ltd | Real estate | 2020 |
| Bosky Ltd | Information & communication | 2018 |
| Botanical Seasons Ltd | Arts & recreation | 2018 |
| Boxers Engineering Ltd | Administrative & support | 2017 |
| Boxfly Media Limited | Information & communication | 2009 |
| Boxing Blueprint Limited | Education | 2023 |
| Boxzy Ltd | Wholesale & retail | 2020 |
| Boya Link Ltd | Real estate | 2025 |
| Bradata Ltd | Education | 2016 |
| Bradán Theatre Ltd | Arts & recreation | 2025 |
| Brandon Hughes Associates Limited | Construction | 2025 |
| Brands R US Limited | Wholesale & retail | 2025 |
| Brar Investments Limited | Construction | 2023 |
| Breeze Freight Services Limited | Transport & logistics | 2025 |
| Brentinnovate Ltd | Information & communication | 2020 |
| Brew Inns PUB Company Limited | Hospitality | 2020 |
| Brick Lane Bikes Limited | Wholesale & retail | 2007 |
| Brickhold Capital Ltd | Real estate | 2026 |
| Brickloom Holdings Ltd | Real estate | 2024 |
| Bridge 32 Management Company Limited | Real estate | 2017 |
| Brighteas Ltd | Hospitality | 2017 |
| Brightex Retail UK Ltd | Wholesale & retail | 2020 |
| Brikory Limited | Professional & scientific | 2026 |
| Brileys Manufacturing Limited | Wholesale & retail | 2019 |
| Britaliano Ltd | Hospitality | 2018 |
| Britcomart Ltd | Wholesale & retail | 2025 |
| British Sky Broadcasting Group Limited | Information & communication | 2014 |
| British Sky Broadcasting Limited | Information & communication | 2015 |
| Broad Electricians Limited | Construction | 2014 |
| Broadmead Developments LLP | | 2020 |
| Brother & Brother Ltd | Manufacturing | 2020 |
| Brother Cafe Limited | Hospitality | 2024 |
| Brown's of ST. Johns Wood LLP | | 2015 |
| BSN Smiles Ltd | Health & social care | 2021 |
| BTA London Ltd | Real estate | 2020 |
| Buch Construction Limited | Construction | 2023 |
| Buczkowski Ltd | Health & social care | 2018 |
| Build for Life Limited | Construction | 2008 |
| Building AK Ltd | Construction | 2006 |
| Building and Decorating Limited | Construction | 2006 |
| Bulk Trading Ltd | Professional & scientific | 2018 |
| Burcraft Limited | Information & communication | 2025 |
| Burraq Kareem Limited | Construction | 2018 |
| Burrows Building Services Limited | Construction | 2016 |
| Busch Pharma Limited | Agriculture & fishing | 2019 |
| Bush Corner Convenience Ltd | Wholesale & retail | 2026 |
| Business Evolution T/A BE Limited | Administrative & support | 2012 |
| Butler Investments Limited | Real estate | 1974 |
| Buttercup Publishing Limited | Information & communication | 2016 |
| Buzzgrade Limited | Real estate | 1999 |
| Buzzpv Limited | Construction | 2024 |
| BVR Tech Ltd | Extraterritorial | 2019 |
| BY Batu Catering Limited | Hospitality | 2020 |
| Bêbado Feliz Ltd | Wholesale & retail | 2025 |
| C & M Properties Investments Limited | Real estate | 2018 |
| C B Electrical & Mechanical Services Ltd | Construction | 2012 |
| C Grou Projects Limited | Information & communication | 2011 |
| C H Design International Ltd | Professional & scientific | 2022 |
| C.F.M.B Delivery Ltd | Wholesale & retail | 2020 |
| C3 ASH Ltd | Administrative & support | 2016 |
| CAB Advisory Ltd | Professional & scientific | 2024 |