| Burst Energy Drink Ltd | Wholesale & retail | 2016 |
| Burton & Co Enterprises Limited | Real estate | 2025 |
| Burtrans Ltd | Transport & logistics | 2025 |
| Bury Park Limited | Information & communication | 2017 |
| Busby House Dental Centre Limited | Health & social care | 2010 |
| Bush Bucket Ltd | Information & communication | 2020 |
| Bush House Care Ltd | Health & social care | 2023 |
| Bush House Properties Limited | Real estate | 2006 |
| Bushey Landscapes Ltd | Administrative & support | 2023 |
| Business & Solving Limited | Professional & scientific | 2016 |
| Business and Investment Global UK Ltd | Administrative & support | 2011 |
| Business Corner Ltd | Administrative & support | 2025 |
| Business IT Solutions Ltd | Information & communication | 2024 |
| Business Leads (UK) Ltd | Information & communication | 2014 |
| Business Outlook Media Ltd | Professional & scientific | 2011 |
| Business Plan Startup Ltd | Professional & scientific | 2015 |
| Business Solutions HV Limited | Information & communication | 2017 |
| Busitales Ltd | Professional & scientific | 2026 |
| Buster Films Limited | Other services | 1986 |
| Busyroute Limited | Real estate | 1987 |
| BUT and Rent Limited | Real estate | 2023 |
| Butchoff Antiques Limited | Wholesale & retail | 1998 |
| Butchoff Properties Limited | Real estate | 2020 |
| Butech Consultancy Limited | Professional & scientific | 2019 |
| Butler and Trinity Limited | Professional & scientific | 2010 |
| Butler Avenue Management Ltd | Administrative & support | 2017 |
| Butler Avenue RTM Company Limited | Households | 2008 |
| Butler Properties 2017 Limited | Real estate | 2017 |
| Butlers Mews (Block a) Management Company Limited | Households | 1989 |
| Butlers Mews (Block B) Management Company Limited | Households | 1989 |
| Butlers Mews (Block C) Management Company Limited | Households | 1989 |
| Butlers Mews (Block D) Management Company Limited | Households | 1989 |
| Butlers Mews (Block E) Management Company Limited | Households | 1989 |
| Butlers Mews (Block G) Management Company Limited | Households | 1989 |
| Butovo Dynamics Ltd | Extraterritorial | 2024 |
| Butterfly Nursing Ltd | Health & social care | 2018 |
| Butterfly Solutions Ltd | Information & communication | 2019 |
| Button END Holdings Limited | Real estate | 2017 |
| Buxwood Limited | Construction | 2006 |
| Buy Gifts Online Limited | Wholesale & retail | 2022 |
| Buy My Pet Food Ltd | Wholesale & retail | 2015 |
| Buy Supply Limited | Wholesale & retail | 2024 |
| BUY4YOU Ltd | Wholesale & retail | 2024 |
| Buybah Ltd | Wholesale & retail | 2024 |
| Buyngrab Ltd | Wholesale & retail | 2022 |
| Buyvault Limited | Wholesale & retail | 2026 |
| Buzy Bees Childcare Limited | Health & social care | 2012 |
| Buzz Property Estates Ltd | Real estate | 2024 |
| Buzzbee Naturals Limited | Wholesale & retail | 2025 |
| Buzzlink Limited | Real estate | 2010 |
| Buzzz City Rooms Ltd | Construction | 2021 |
| BV Consulting UK Limited | Administrative & support | 2016 |
| BVI Projects Ltd | Construction | 2018 |
| BVM Associates Ltd | Real estate | 2013 |
| BVM Construction Limited | Construction | 2024 |
| BW Bars Ltd | Hospitality | 2019 |
| BW Foundation | Other services | 2007 |
| BWC Holdco Limited | Professional & scientific | 2024 |
| BWF Development Company Limited | Construction | 2007 |
| BWL Group Ltd | Construction | 2024 |
| Bwow Solutions Ltd | Information & communication | 2025 |
| BWS Consult Limited | Professional & scientific | 2025 |
| BY Design (Management) Limited | Real estate | 2025 |
| BY Direct Limited | Wholesale & retail | 2016 |
| BY FI Limited | Other services | 2017 |
| BY Malene Birger UK Ltd. | Wholesale & retail | 1978 |
| BY Sharan Limited | Wholesale & retail | 2019 |
| Byalura International Properties Ltd | Real estate | 2025 |
| Bydand London Limited | Real estate | 2019 |
| Bygeotel Ltd | Construction | 2022 |
| Bygrid Construct Ltd | Construction | 2025 |
| Byimpact Mortgages Ltd | Financial services | 2026 |
| BYO3 LAB UK Limited | Wholesale & retail | 2023 |
| Byova Ltd | Other services | 2024 |
| Byron Hill Holdings Limited | Administrative & support | 2008 |
| Byron Hill Investments Limited | Administrative & support | 2008 |
| Byron Road Limited | Real estate | 2022 |
| Byronswell Limited | Water & waste | 2004 |
| Bysack Ltd | Professional & scientific | 2023 |
| Bysc Limited | Professional & scientific | 2016 |
| Byteloop AI Limited | Information & communication | 2024 |
| BZT Properties Ltd | Financial services | 2025 |
| B’S Beauty Blend Ltd | Other services | 2025 |
| C & a Contractor Limited | Construction | 2009 |
| C & a Electrical Services Ltd | Construction | 2008 |
| C & a Installation Ltd | Construction | 2016 |
| C & F Homes Limited | Real estate | 2021 |
| C & G Builders and Developers Limited | Construction | 2021 |
| C & J Harper Services Limited | Manufacturing | 2015 |
| C & K Healthcare Limited | Health & social care | 2012 |
| C & M Dental Care Limited | Health & social care | 2010 |
| C & M Incorporated Ltd | Real estate | 2020 |
| C & R Enterprise Ltd | Real estate | 2023 |
| C & S Management Consultancy Ltd | Professional & scientific | 2012 |
| C & SON Construction Ltd | Construction | 2015 |
| C 7LS Limited | Real estate | 2022 |
| C a Thomas Ltd | Professional & scientific | 2024 |
| C Birsan Ltd | Construction | 2021 |
| C Braham Ltd | Health & social care | 2019 |
| C Click Ltd | Other services | 2018 |