| Build Tronic Ltd | Construction | 2025 |
| Build Your Dream Limited | Construction | 2017 |
| Build&Gain Ltd | Real estate | 2020 |
| BUILD360.TEAM Ltd | Construction | 2024 |
| Buildcare and Property Maintenance Ltd | Construction | 2025 |
| Builder 4 YOU Limited | Construction | 2014 |
| Builder Build Ltd | Construction | 2026 |
| Builders East London Ltd | Construction | 2015 |
| Builders Junction Ltd | Construction | 2023 |
| Buildersforall Ltd | Construction | 2025 |
| Buildfine UK Limited | Construction | 2019 |
| Building Complex Structures Limited | Construction | 2026 |
| Building Integration Services Ltd | Construction | 2025 |
| Building Maintenance & Services (UK) Ltd | Construction | 2010 |
| Building Trade Ltd | Construction | 2024 |
| Building&Plumbing Ltd | Construction | 2024 |
| BUILDING1FUTURE Limited | Construction | 2026 |
| Buildingbulls Ltd | Construction | 2024 |
| Buildings Maintenance and Construction Limited | Construction | 2020 |
| Buildsphere Solutions Ltd | Professional & scientific | 2026 |
| Buildto Scaffolding Limited | Construction | 2026 |
| Buildwave Construction Ltd | Construction | 2025 |
| Buildx Energy Ltd | Wholesale & retail | 2021 |
| Buildx Solutions Ltd | Information & communication | 2021 |
| Built in Power Ltd | Construction | 2026 |
| Built Plus Ltd | Construction | 2023 |
| Builtopia Ltd | Real estate | 2023 |
| Buji Studio Ltd | Manufacturing | 2025 |
| Bukhari Collections Ltd | Wholesale & retail | 2024 |
| Bukhari Global Limited | Professional & scientific | 2024 |
| Bulava Properties Limited | Real estate | 2019 |
| Bulbul Academy of Fine Arts,(Bafa) UK Ltd | Education | 2024 |
| Bulegiles Ltd | Health & social care | 2020 |
| Bulent Properties Ltd | Real estate | 2024 |
| Bulgroup Developments Ltd | Construction | 2021 |
| Bulgroup Estate Ltd | Real estate | 2021 |
| Bulgroup Holdings Ltd | Financial services | 2025 |
| Bulgroup Ltd | Construction | 2016 |
| Bulgroup Properties Ltd | Real estate | 2018 |
| Buliga Limited | Construction | 2017 |
| Bulk Basket Foods Limited | Wholesale & retail | 2025 |
| Bulkory Ltd | Wholesale & retail | 2025 |
| Bulletproof Business Limited | Education | 2019 |
| Bulls 'N' Birds Limited | Hospitality | 2025 |
| Bullseye Construction & Maintenance Ltd | Other services | 2023 |
| Bulpower Ltd | Construction | 2025 |
| Bultech Limited | Construction | 2012 |
| Bulwark Reliance Limited | Professional & scientific | 2010 |
| Bumble Boards Ltd | Manufacturing | 2020 |
| Bumblebee Bodyworks Ltd | Wholesale & retail | 2022 |
| Bunch London Ltd | Manufacturing | 2020 |
| Bundo Khan Ltd | Hospitality | 2023 |
| Bundu Khan Ilford Limited | Hospitality | 2025 |
| Bunify Harrow Ltd | Hospitality | 2024 |
| Bunon Trend Ltd | Wholesale & retail | 2023 |
| Bunore Limited | Wholesale & retail | 2025 |
| Bunz & Broth Ltd | Hospitality | 2025 |
| BUR Interiors Ltd | Construction | 2019 |
| Burak Asset Management Ltd | Professional & scientific | 2016 |
| Burak Traderz Ltd | Wholesale & retail | 2025 |
| Buraq Enterprises London Ltd | Households | 2026 |
| Buraq K9 Ltd | Administrative & support | 2023 |
| Buraq Riders Limited | Administrative & support | 2023 |
| Buraq Security Ltd | Administrative & support | 2026 |
| BURAQ1 Limited | Wholesale & retail | 2023 |
| Bura’S Construction Ltd | Construction | 2022 |
| Burbrothersinteriors Ltd | Construction | 2023 |
| Burch Design Ltd | Manufacturing | 2020 |
| Burger & Fish Melts Limited | Hospitality | 2024 |
| Burger Store Ltd | Hospitality | 2025 |
| Burger Wala Limited | Hospitality | 2020 |
| Burger Yard Limited | Hospitality | 2020 |
| Burgers Studio Limited | Hospitality | 2019 |
| Burgogi Ilford Ltd | Real estate | 2021 |
| Burhan & Brother Ltd | Wholesale & retail | 2023 |
| Burney (Romford) Limited | Real estate | 2013 |
| Burney Essex Ltd | Real estate | 2014 |
| Burning MAN Media Limited | Information & communication | 2014 |
| Burns Chemist Limited | Wholesale & retail | 2004 |
| Burrak Ltd | Professional & scientific | 2016 |
| Burrak Properties Ltd | Real estate | 2025 |
| Burraq Hire Solutions Ltd | Administrative & support | 2012 |
| Bursting BUD International Ltd | Wholesale & retail | 2018 |
| Burton Grange Investments Limited | Administrative & support | 2011 |
| Burtons Food Delivery Service Limited | Hospitality | 2025 |
| Busho Limited | Wholesale & retail | 2022 |
| Business Advisory Services Ltd | Administrative & support | 2024 |
| Business Applications Services Limited | Information & communication | 2015 |
| Business First Exchange Ltd | Financial services | 2016 |
| Business Solutions Europa Limited | Professional & scientific | 2005 |
| Business Solutions Services Limited | Professional & scientific | 2017 |
| Business Solutions(Uk) Limited | Real estate | 2020 |
| Businessip Solutions Ltd | Administrative & support | 2013 |
| Busko Parts Ltd | Wholesale & retail | 2023 |
| Busuioc Construction Ltd | Construction | 2024 |
| Busy Apartments Ltd | Hospitality | 2025 |
| Busy Home Buildings Ltd | Real estate | 2023 |
| Busy Street Limited | Wholesale & retail | 2025 |
| Busymost Limited | Real estate | 1988 |
| Buth Solutions Limited | Professional & scientific | 2016 |