| Broom Consultants Limited | Administrative & support | 2000 |
| Broom Group Ltd | Financial services | 2024 |
| Broughton Plant Hire and Sales Limited | Administrative & support | 1983 |
| Brow Doctor Ltd | Other services | 2025 |
| Brown and Brougham Limited | Professional & scientific | 2010 |
| Brown's Pet Range Limited | Extraterritorial | 2012 |
| Brownbread Artisan Ltd | Wholesale & retail | 2020 |
| Brunenzo Ltd | Wholesale & retail | 2025 |
| Bryant Boats (UK) Ltd | Wholesale & retail | 2017 |
| Bryco 2 Limited | Real estate | 2025 |
| Bryco Civils and Construction Services Ltd | Construction | 2022 |
| Bryco Construction Group Limited | Construction | 2022 |
| Bryco Haulage and Waste Management Limited | Construction | 2022 |
| Bryco Infinity Construction Ltd | Construction | 2026 |
| Bryco Infinity Limited | Real estate | 2025 |
| Bryco Infinity Two Ltd | Real estate | 2026 |
| Bryco Limited | Real estate | 2023 |
| Bryco Property Developments Limited | Construction | 2022 |
| BSA Bargains Ltd | Wholesale & retail | 2023 |
| BSE Building Sevices Ltd | Construction | 2026 |
| BSF Bespoke Counter Tops Ltd | Manufacturing | 2018 |
| BSF Solid Surfaces Limited | Manufacturing | 1991 |
| Bsipp Limited | Health & social care | 2020 |
| BSL Management Holdings Ltd | Financial services | 2021 |
| BSL Management Services Ltd | Information & communication | 2010 |
| BSL One Stop Solutions Limited | Professional & scientific | 2016 |
| BST (Broadland Safety Testing) Ltd | Professional & scientific | 2026 |
| BT Zone Ltd | Wholesale & retail | 2023 |
| BTS Carpentry Ltd | Construction | 2018 |
| Bubble BEE Limited | Administrative & support | 2026 |
| Bubbles & Beyond Ltd | Wholesale & retail | 2025 |
| Bubbles & Bows Dog Groomers Ltd | Other services | 2022 |
| Bubbles Prestige Limited | Other services | 2005 |
| Buch Media Limited | Information & communication | 2020 |
| Bucinski Ltd | Construction | 2020 |
| Buckingham James Financial Services Limited | Financial services | 2012 |
| Buckley Alan Limited | Administrative & support | 2021 |
| Buckley Builders London Limited | Construction | 2018 |
| Buckley Rose Limited | Professional & scientific | 1999 |
| Bucks Barbers Canalside Ltd | Other services | 2017 |
| Buddies Backyard Ltd | Arts & recreation | 2025 |
| Build Makers Property Group Ltd | Real estate | 2026 |
| BUILD2CREATE Ltd | Administrative & support | 2018 |
| Builders Convert Ltd | Construction | 2019 |
| Buildmaster Essex Ltd | Construction | 2015 |
| Buildtech Property Ltd | Construction | 2020 |
| Bukk Ltd | Construction | 2025 |
| Buku Ltd | Professional & scientific | 2010 |
| Bulfix Ltd | Construction | 2006 |
| Bulgarian Vegetables Tina Ltd | Manufacturing | 2020 |
| Bulk Bonus Limited | Wholesale & retail | 2025 |
| Bulk Buyers Ltd | Wholesale & retail | 2018 |
| Bulktech Solutions Ltd | Wholesale & retail | 2026 |
| Bullfinch Equity Release Ltd | Financial services | 2018 |
| Bundle Services Ltd | Administrative & support | 2008 |
| Bunton Enterprises Limited | Extraterritorial | 2006 |
| Burbo Ltd | Financial services | 2024 |
| Burford Financial Services Limited | Extraterritorial | 2014 |
| Burland Consultancy Limited | Information & communication | 2005 |
| Burlington Mayfair Ltd | Professional & scientific | 2019 |
| Burman Recruitment Limited | Information & communication | 2018 |
| Burns Brightiff Consulting Ltd | Administrative & support | 2012 |
| Burntwood Process Systems Limited | Professional & scientific | 2003 |
| Burntwood Valves Limited | Wholesale & retail | 1984 |
| Burrells Investment Group (Shenfield) Limited | Real estate | 2024 |
| Burty and Sons Limited | Professional & scientific | 2010 |
| Burwood Services Limited | Professional & scientific | 2024 |
| Burwood Support Ltd | Administrative & support | 2026 |
| Burylleb Ltd | Financial services | 2020 |
| Bushmead Estates Ltd | Real estate | 2020 |
| Business Analysis Services Ltd | Information & communication | 2021 |
| Business Change Management Academy Limited | Information & communication | 2025 |
| Business Print Services Limited | Manufacturing | 2003 |
| Business Transitions Consultancy Limited | Information & communication | 2011 |
| Busman Interiors Limited | Administrative & support | 2010 |
| Busy Beelders Limited | Construction | 2025 |
| Busy Bees Locks & Doors Ltd | Other services | 2004 |
| Butterfly Hair Salon Limited | Other services | 2014 |
| Buttress Property Limited | Real estate | 2023 |
| Buttsbury Electrical Ltd | Energy | 2019 |
| Buxton Ryan & Co Ltd | Extraterritorial | 2015 |
| Buzz Smith Limited | Professional & scientific | 2020 |
| Buzz Trade Incorporation Limited | Wholesale & retail | 2021 |
| BW Care Ltd | Health & social care | 2021 |
| Bwellhut Ltd | Information & communication | 2025 |
| BX Construction Ltd | Construction | 2022 |
| Byron Group Limited | Wholesale & retail | 2017 |
| Byteborne Technologies Ltd | Information & communication | 2007 |
| Byteware Ltd | Professional & scientific | 2021 |
| B’Anyi Real Estate Group Limited | Real estate | 2025 |
| C & C Lettings Limited | Real estate | 2015 |
| C & C Plumbing & Heating (Southern) Limited | Construction | 2008 |
| C & D Building (Essex) Limited | Construction | 2017 |
| C & M Belfast Properties Ltd | Administrative & support | 2016 |
| C & R Timber Merchants Limited | Wholesale & retail | 1982 |
| C a Entertainment and Consultants Ltd | Professional & scientific | 2017 |
| C Copley Limited | Professional & scientific | 2013 |
| C DE Abreu Limited | Construction | 2013 |
| C Logistics Ltd | Transport & logistics | 2011 |
| C M E & Company | | 1994 |