| Bridge Properties London Limited | Real estate | 2016 |
| Bridgeway Consultancy Ltd | Professional & scientific | 2024 |
| Bright International Ltd | Wholesale & retail | 2021 |
| Bright Star Construction Ltd | Construction | 2020 |
| Bright Sun Ltd | Real estate | 2010 |
| Bright View Glazing Ltd | Construction | 2025 |
| Brightedge Consultancy Ltd | Professional & scientific | 2026 |
| Brighter Dwellings Ltd | Real estate | 2024 |
| Brightfield Ltd | Professional & scientific | 2026 |
| Brilliance Care Ltd | Public administration | 2023 |
| Brilliant Cleaners Ltd | Administrative & support | 2024 |
| Brilond Limited | Administrative & support | 2019 |
| Brimur Ltd | Administrative & support | 2011 |
| Brindle Convenience Ltd | Wholesale & retail | 2025 |
| Brit Global Management Ltd | Administrative & support | 2018 |
| Britain Estates Limited | Real estate | 2026 |
| Britannia Supplies UK Ltd | Wholesale & retail | 2025 |
| Britbuy Solutions Ltd | Wholesale & retail | 2025 |
| Brite Solutions Electrical Limited | Other services | 2012 |
| Britian Trading Ltd | Wholesale & retail | 2021 |
| British Nepalese Premier League Limited | Arts & recreation | 2019 |
| Briton Consultants & Materials Technology Ltd | Construction | 2022 |
| Britstone Construction Ltd | Construction | 2025 |
| Brittian Flat 4 Limited | Households | 2024 |
| Brittian Flat 5 Limited | Households | 2024 |
| Brittian Flat 6 Limited | Households | 2024 |
| Britware Ltd | Wholesale & retail | 2024 |
| Brixton Cake Ltd | Wholesale & retail | 2020 |
| Broaden Horizon Ltd | Health & social care | 2018 |
| Bromley Broadcasting Ltd | Information & communication | 2022 |
| Bronte Estates Ltd | Real estate | 2022 |
| Brook House F.C. Limited | Arts & recreation | 1998 |
| Brooog Ltd | Information & communication | 2020 |
| Bros & Partners Co Ltd | Hospitality | 2025 |
| Brother Builders Limited | Construction | 2021 |
| Brothers AS Ltd | Construction | 2024 |
| Brothers Glazing Ltd | Construction | 2024 |
| Brothers Property Investments Ltd | Real estate | 2018 |
| Brothers Restaurant Hayes Ltd | Hospitality | 2019 |
| Brothers Staircase Ltd | Manufacturing | 2023 |
| Brown Boys PNC Limited | Construction | 2025 |
| Brown Builders and Decorators Ltd | Construction | 2024 |
| BRS Rendering and External Wall Insulation Ltd | Construction | 2026 |
| Bruisers Ltd | Wholesale & retail | 2025 |
| Brunel Airport Chauffeurs Ltd. | Transport & logistics | 2014 |
| Brushie Limited | Wholesale & retail | 2024 |
| Brushwood Property Services Limited | Construction | 2006 |
| Bryan's Heating Services Ltd | Construction | 2019 |
| Bryanstone Property Services Ltd | Administrative & support | 2026 |
| Brzask Ltd | Construction | 2016 |
| BS Carpets Ltd | Wholesale & retail | 2022 |
| BS Cons Ltd | Construction | 2020 |
| BS Freight Ltd | Transport & logistics | 2024 |
| BS Guraya Builder Ltd | Construction | 2017 |
| BS Kitchen & Bedroom Ltd | Construction | 2017 |
| BS Kitchens & Bedrooms Ltd | Construction | 2024 |
| BS Thind Builders Ltd | Construction | 2024 |
| BS Virk Transport Ltd | Transport & logistics | 2025 |
| BS Windows Ltd | Construction | 2018 |
| BSA Group Ltd | Real estate | 2026 |
| BSD Building Services Limited | Construction | 2019 |
| BSG Caterers Limited | Hospitality | 2025 |
| BSK Investment Ltd | Real estate | 2023 |
| BSP Pressure Washers Ltd | Wholesale & retail | 2024 |
| BT Pizza Limited | Hospitality | 2026 |
| Btecsol Limited | Information & communication | 2009 |
| Bubble Network Ltd | Administrative & support | 2020 |
| Bubbles Electrician Ltd | Construction | 2014 |
| Buckingham Mortgage Services Limited | Financial services | 2003 |
| Buddha Estate Agents Limited | Real estate | 2026 |
| Buddha Mortgage Limited | Financial services | 2025 |
| Budget Tyres & Motors Ltd | Wholesale & retail | 2019 |
| Budhraja Property Group Ltd | Real estate | 2021 |
| Bugendaitech UK Ltd | Information & communication | 2021 |
| Build Bright Construction Ltd | Construction | 2025 |
| Build Dream Homes Ltd | Construction | 2026 |
| Build Dreams Ltd | Manufacturing | 2022 |
| Build Majastic Limited | Construction | 2025 |
| Build UK Construction Ltd | Construction | 2025 |
| BUILD4U Limited | Construction | 2023 |
| Buildbuddy Construction Ltd | Construction | 2016 |
| Buildbuddy Investments Ltd | Real estate | 2024 |
| Buildcore Investments Ltd | Real estate | 2026 |
| Builders 4U Limited | Administrative & support | 2006 |
| Builders From Doaba Limited | Construction | 2023 |
| Buildforge Beam Ltd | Construction | 2026 |
| Buildforge Ltd | Construction | 2025 |
| Building Outfitters Ltd | Construction | 2024 |
| Buildswell Ltd | Construction | 2019 |
| Buildwise UK Construction Ltd | Construction | 2025 |
| Bulby Ltd | Transport & logistics | 2019 |
| Bull Security Limited | Wholesale & retail | 2015 |
| BUR & GUR Ltd | Hospitality | 2023 |
| Burberry Retail Park Ltd | Real estate | 2026 |
| Burg Online Express Ltd | Wholesale & retail | 2024 |
| Burger Plug Ltd | Hospitality | 2025 |
| BUS Training Limited | Education | 2013 |
| Bush Vapes and Phones Limited | Wholesale & retail | 2025 |
| Bushey Food Express Limited | Wholesale & retail | 2014 |
| Business 4 Accountant Limited | Professional & scientific | 2011 |