| BROADWAY3 Limited | Wholesale & retail | 2012 |
| Brohan Limited | Construction | 2012 |
| Broken EAR Limited | Arts & recreation | 2016 |
| Bromley Event Catering Ltd | Hospitality | 2023 |
| Brondesbury Park Estates Ltd | Real estate | 2023 |
| Brook Farm Racing Limited | Real estate | 2011 |
| Brooke House Care Ltd | Health & social care | 2021 |
| Brookfield Farm Limited | Agriculture & fishing | 2026 |
| Brookhill Court Freehold Limited | Households | 2002 |
| Brooklyn Consulting Limited | Information & communication | 2021 |
| Brooksie Maintenance Ltd | Professional & scientific | 2020 |
| Brookvale Capital Ltd | Construction | 2025 |
| Broomfield Park Swimming and Recreational Club Limited | Arts & recreation | 1994 |
| Bros in Limited | Hospitality | 2025 |
| Brospective Limited | Wholesale & retail | 2025 |
| Browndog Construction Ltd | Administrative & support | 2007 |
| BROWSTUDIO1 Limited | Other services | 2017 |
| Bruce Gallup Scenic Painting Limited | Administrative & support | 2010 |
| Brunel Banter Ltd | Professional & scientific | 2022 |
| Brunel Catering Ltd | Wholesale & retail | 2022 |
| Brunel Event Catering Ltd | Administrative & support | 2025 |
| Brunswick Advisory Consultants Limited | Other services | 2013 |
| Brunswick Supported Living Services Ltd | Health & social care | 2012 |
| Brunton Avenue Properties Limited | Real estate | 2025 |
| Brydon Brothers Ltd | Wholesale & retail | 2014 |
| Brzee Investment Ltd | Real estate | 2013 |
| BSA Management Consultants Ltd | Professional & scientific | 2023 |
| BSC Employees Trustees Limited | Extraterritorial | 2025 |
| Bsluk Ltd | Wholesale & retail | 2018 |
| BSP Consultants Limited | Administrative & support | 2016 |
| BSR Networks Ltd | Professional & scientific | 2019 |
| Bstefan&Lucas Limited | Other services | 2025 |
| Bstefaniulian Ltd | Construction | 2019 |
| Bstv Limited | Information & communication | 2001 |
| Bubbanuki Properties Limited | Real estate | 2021 |
| Bubble Tea Bullring Ltd | Hospitality | 2022 |
| Bubble Umbrella Limited | Wholesale & retail | 2023 |
| Bubu International Limited | Professional & scientific | 2025 |
| Bubu Plumbing & Heating Services Ltd | Construction | 2024 |
| Buckley Court Freehold Limited | Real estate | 2011 |
| BUD Duck UK Limited | Administrative & support | 2015 |
| Budaks Foods Limited | Hospitality | 2015 |
| Buenki Caffee Ltd | Hospitality | 2024 |
| Buenotherapy Limited | Administrative & support | 2010 |
| Build OR FIX Ltd | Construction | 2026 |
| Buildmate Ltd | Other services | 2008 |
| Built 4 ALL Ltd | Construction | 2021 |
| BUL Catering Ltd | Hospitality | 2022 |
| Bulb Construction Limited | Construction | 2026 |
| Bulestate Ltd | Real estate | 2017 |
| Bullens Rentals Limited | Real estate | 2022 |
| Bultrade Capital Limited | Real estate | 2025 |
| Bumble & Batter Events Ltd | Hospitality | 2025 |
| Bunnytreats Limited | Manufacturing | 2025 |
| BUR Ming Limited | Real estate | 2016 |
| Bure Court (Freehold) Limited | Households | 2006 |
| Burgess Property Investments Limited | Real estate | 2002 |
| Burgundy Tulip Limited | Other services | 2016 |
| Burke Niazi Limited | Professional & scientific | 2010 |
| Burlington Haulage Ltd | Transport & logistics | 2015 |
| Burning Hammer Properties Ltd | Real estate | 2020 |
| Burnside Close Freehold Limited | Households | 2003 |
| Burnside House Construction Ltd | Construction | 2023 |
| Bursthaven Limited | Financial services | 1996 |
| Burwork Limited | Information & communication | 1988 |
| Bush Hill Construction Limited | Construction | 1979 |
| Bushbaby Gardens & Landscaping Ltd | Administrative & support | 2021 |
| Business Consulting Services Ltd | Professional & scientific | 2016 |
| Business Energy Renewals Limited | Other services | 2013 |
| Business Management Plus Limited | Hospitality | 2018 |
| Business Planning Limited | Administrative & support | 2003 |
| Busylindsay Limited | Financial services | 2019 |
| Butler & Stag (Chingford) Limited | Real estate | 2015 |
| Butler & Stag BOW Limited | Real estate | 2015 |
| Butler & Stag Holdings Ltd | Real estate | 2025 |
| Butler & Stag Land & New Homes Ltd | Real estate | 2020 |
| Butler & Stag Theydon Bois Ltd | Real estate | 2017 |
| Butmar Ltd | Construction | 2018 |
| Buying Power Solutions Ltd | Wholesale & retail | 2023 |
| BVM Consults Ltd | Information & communication | 2025 |
| BY Hdesign Limited | Professional & scientific | 2020 |
| BY Olivia Hines Ltd | Other services | 2021 |
| Byronic Limited | Professional & scientific | 2017 |
| Bytes Reality Ltd | Information & communication | 2021 |
| C & E Estimators Limited | Professional & scientific | 2025 |
| C & G Homes Limited | Real estate | 2020 |
| C & V Management Company Limited | Households | 2021 |
| C & V Management Limited | Households | 1991 |
| C a Builders Ltd | Construction | 2022 |
| C and R Design Ltd | Professional & scientific | 2006 |
| C Capital Media Ltd | Financial services | 2017 |
| C F Commercial Limited | Real estate | 2008 |
| C G Fittings Ltd | Professional & scientific | 2023 |
| C J Advisory Ltd | Administrative & support | 2019 |
| C J E Investments Limited | Financial services | 2014 |
| C L & R Properties Limited | Real estate | 2017 |
| C Magri Motors Ltd | Wholesale & retail | 2024 |
| C T Lawrence Ltd | Construction | 2017 |
| C Thornton Investments Ltd | Construction | 2024 |
| C W Newton Limited | Other services | 2004 |