| Brilliant Housing Ltd | Real estate | 2026 |
| Brinik Ltd | Wholesale & retail | 2021 |
| Bristol Grilled Chicken Limited | Hospitality | 2023 |
| Britannia Heritage Homes Limited | Construction | 2025 |
| Britannic Security Systems Limited | Administrative & support | 1994 |
| Brite Consutruction and Management Ltd | Construction | 2020 |
| Britehomes Ltd | Administrative & support | 2025 |
| British Comics Limited | Wholesale & retail | 2013 |
| British Institute of Embalmers (the) | Other services | 1929 |
| Britplant Limited | Wholesale & retail | 2024 |
| Britsoft Solutions Limited | Information & communication | 2017 |
| Brivox Ltd | Construction | 2025 |
| BRL Building Services Limited | Construction | 2017 |
| Brnch & Co Ltd | Hospitality | 2025 |
| Broad Green Construction Limited | Construction | 2023 |
| Broad Oaks Building Solutions Limited | Manufacturing | 2011 |
| Broad Oaks Homes Limited | Real estate | 2022 |
| Broad Oaks Residents Management Company Limited | Households | 2005 |
| Broadacre Gardens Management Company Limited | Real estate | 2013 |
| Broadacre Homes Limited | Construction | 2021 |
| Broadford Surveying Ltd | Professional & scientific | 2015 |
| Broadoaks Consulting Limited | Administrative & support | 2024 |
| Broadoaks Management Company (Solihull) Limited | Households | 2004 |
| Broadstreet Wealth Management Limited | Administrative & support | 2020 |
| Brockworth Limited | Real estate | 2026 |
| Broga Irish Dance Limited | Wholesale & retail | 2024 |
| Broke 'N Bone Kitchen Ltd | Hospitality | 2021 |
| Bromford Steel Limited | Professional & scientific | 1916 |
| Bromsgrove Road Limited | Construction | 2022 |
| Bronze Studios Ltd | Other services | 2025 |
| Brookestand Limited | Other services | 2024 |
| Brookside Fruits Cafe Limited | Hospitality | 2018 |
| Brookson (5365H) Limited | Administrative & support | 2007 |
| Broom Cottage Properties Limited | Real estate | 2017 |
| Brothers Decor Limited | Other services | 2019 |
| Brothers Turvey Ltd | Wholesale & retail | 2018 |
| Broughton Capital Ltd | Financial services | 2002 |
| Browfix UK LLP | | 2021 |
| Brown Additions Limited | Real estate | 2021 |
| Brrr Property Ltd | Administrative & support | 2025 |
| BRS (Southwest) Limited | Financial services | 2025 |
| Bruce Main-Smith and Company Limited | Education | 2013 |
| Brueton Lettings Limited | Real estate | 2022 |
| Brunchin Cafe Ltd | Hospitality | 2023 |
| Brundell Consultancy Services Limited | Professional & scientific | 2017 |
| Brunel Investments Limited | Professional & scientific | 2002 |
| Brunswick Services Limited | Financial services | 2019 |
| BRW Business Development Ltd | Professional & scientific | 2015 |
| Brxpress Ltd | Transport & logistics | 2021 |
| Bryant Consultancy Limited | Professional & scientific | 2022 |
| Bryc Ltd | Information & communication | 2025 |
| Bryony School Estates Limited | Real estate | 2023 |
| Bryony School Limited | Education | 2023 |
| Bs&T Digital Limited | Professional & scientific | 2013 |
| Bs&T Holdings Ltd | Financial services | 2021 |
| BSA Environmental Limited | Water & waste | 2018 |
| Bscx Media Ltd | Information & communication | 2025 |
| BSG Assets Limited | Real estate | 2016 |
| BSG Property Ltd | Real estate | 2024 |
| Bsgh Limited | Administrative & support | 2007 |
| BSL Holdings Limited | Financial services | 2021 |
| BSS Property Group Ltd | Real estate | 2021 |
| BTS1 Group Ltd | Education | 2026 |
| BU Homes Limited | Real estate | 2014 |
| BU Salons Ltd | Other services | 2019 |
| BU Suites Limited | Hospitality | 2025 |
| BU Synergy Limited | Professional & scientific | 2025 |
| Bubble Jumper Limited | Real estate | 2020 |
| Bubbles Linen and Laundry Services Limited | Other services | 2025 |
| Bubblogy Ltd | Manufacturing | 2025 |
| Buckcroft Ltd | Health & social care | 2023 |
| Buckingham Lodge (L.Spa) Limited | Households | 1998 |
| Bucklers of London Limited | Financial services | 2025 |
| Buckley's Deli Limited | Wholesale & retail | 2015 |
| Bucksbourne Limited | Hospitality | 2017 |
| Build Design Solutions Ltd | Construction | 2024 |
| Build Elec Ltd | Construction | 2023 |
| Build the Future Limited | Administrative & support | 2018 |
| Building Alliance Community Interest Company | Construction | 2015 |
| Building Better Ltd | Construction | 2025 |
| Building Plastics Holdings Limited | Extraterritorial | 2005 |
| Bullion Buyer Ltd | Wholesale & retail | 2024 |
| Bullseye Food Packaging Limited | Administrative & support | 2018 |
| Bulsatcom Investment Limited | Financial services | 2014 |
| Buraaq Store Limited | Hospitality | 2021 |
| Burford AUX Limited | Professional & scientific | 2024 |
| Burford Bench Holdings Limited | Financial services | 2024 |
| Burgess Clinical Limited | Health & social care | 2022 |
| Burghfield Common Management Company Limited | Households | 2019 |
| Burnett Road Ltd | Other services | 2020 |
| Burning Platform Solutions Ltd | Professional & scientific | 2016 |
| Burrwood Interiors Limited | Professional & scientific | 2024 |
| Bushwood Drive (Dorridge) Management Company Limited | Extraterritorial | 2013 |
| Business Development in Construction Ltd | Professional & scientific | 2021 |
| Business Energy Index Limited | Professional & scientific | 2016 |
| Business Review Consulting Services Limited | Financial services | 2004 |
| Business Services and Analytics Limited | Information & communication | 2019 |
| Businessesforsale.Com Ltd | Information & communication | 2011 |
| Buster Burke Advisory Limited | Professional & scientific | 2012 |
| Buster Burke Investments Limited | Professional & scientific | 2003 |