| Bonnylen Limited | Health & social care | 2015 |
| Booshy Limited | Information & communication | 2025 |
| Bord Civil Engineering Ltd | Construction | 2020 |
| Bossuba Limited | Real estate | 2025 |
| Botchway Architecture and Surveying Services Ltd | Professional & scientific | 2025 |
| Boundary Condition Ltd | Arts & recreation | 2022 |
| Boutique Beleza Limited | Manufacturing | 2020 |
| Bozheng Culture & Media Ltd | Education | 2019 |
| Bpfc FIX Ltd | Construction | 2019 |
| BR Handyman Services Ltd | Construction | 2023 |
| BR Vision Limited | Professional & scientific | 2025 |
| Brabble Consulting Ltd | Professional & scientific | 2023 |
| Brainsparkacademy Ltd | Education | 2025 |
| Bramble & Batch Ltd | Manufacturing | 2026 |
| Braye Electrical Contractors Ltd | Other services | 2015 |
| Brazukskip & Motorcycle for Rent Ltd | Water & waste | 2022 |
| Breitecom Limited | Wholesale & retail | 2010 |
| Bremkhel Ltd | Real estate | 2022 |
| Brenda Beverley Ltd | Wholesale & retail | 2017 |
| Brenflo Limited | Health & social care | 2021 |
| Brenley Park Management Limited | Households | 2011 |
| Brewzone Africa Limited | Wholesale & retail | 2023 |
| BRH Electrical Services Ltd | Construction | 2007 |
| Brickman Investments Limited | Real estate | 2024 |
| Bricks and Wood Limited | Construction | 2024 |
| Brickwell Investments Limited | Real estate | 2024 |
| Bridging Cultures Ltd | Administrative & support | 2025 |
| Bright a Day Limited | Construction | 2024 |
| Bright Beginners Limited | Education | 2017 |
| Bright Skills Sphere Ltd | Wholesale & retail | 2024 |
| Brighter Days Consultancy Ltd | Health & social care | 2013 |
| Brightly Furnished Rentals UK Ltd | Real estate | 2025 |
| Brightwave Creative Ltd | Information & communication | 2024 |
| Britalian Eyewear Limited | Wholesale & retail | 2015 |
| British West India Regiments Heritage Trust CIC | Education | 2023 |
| Britship Logistics Ltd | Transport & logistics | 2025 |
| Britzone Ltd | Wholesale & retail | 2025 |
| Broadberry International Ltd | Real estate | 2019 |
| Broadway Hill Limited | Extraterritorial | 2019 |
| Brokk Trader Limited | Wholesale & retail | 2016 |
| Brompton Design and Build Ltd | Construction | 2010 |
| Broweld Limited | Construction | 2017 |
| Brownoak Ltd | Hospitality | 2018 |
| Brows by TAM Limited | Other services | 2025 |
| Browse Bazaar Ltd | Wholesale & retail | 2024 |
| BRS & Brothers Limited | Wholesale & retail | 2018 |
| Bruntons Aero Products Limited | Manufacturing | 1895 |
| Brymill Stockholders Limited | Extraterritorial | 1948 |
| BSC Electrical and Heating Services Ltd | Construction | 2020 |
| Bsck Ltd | Wholesale & retail | 2019 |
| BSP Property Services Ltd | Construction | 2016 |
| Buczo Company Ltd | Transport & logistics | 2022 |
| Build Matrics Ltd | Information & communication | 2026 |
| Building Design Ltd | Construction | 2015 |
| Building Sight Services Limited | Construction | 2023 |
| Buildmatic Exhibitions and Events Ltd | Construction | 2019 |
| Buildna Ltd | Construction | 2016 |
| Builtd Limited | Construction | 2024 |
| Bulfix 1 Ltd | Construction | 2017 |
| Bulgas Ltd | Administrative & support | 2017 |
| Bulgin Builders Limited | Construction | 2017 |
| Bull & Bates Limited | Construction | 2019 |
| Buona Vita Ltd | Wholesale & retail | 2020 |
| Buraq INT Ltd | Wholesale & retail | 2022 |
| Burton Construction Group Limited | Construction | 2006 |
| Burton Group Developments Ltd | Real estate | 2008 |
| Bushby Builders Ltd | Construction | 2023 |
| Busy BEE Spotless Ltd | Administrative & support | 2026 |
| Busy Diamonds Nursery Limited | Health & social care | 2019 |
| Butler Masonry Restoration Ltd | Construction | 2026 |
| Butterworks Ltd | Wholesale & retail | 2024 |
| Buty Co. Limited | Hospitality | 2026 |
| Buzz Line Digital Ltd | Information & communication | 2025 |
| BW Build Solutions Ltd | Manufacturing | 2025 |
| BWP Advisers Limited | Professional & scientific | 2024 |
| C & R Services (London) Limited | Administrative & support | 2013 |
| C Jenkins Trading Ltd | Financial services | 2019 |
| C K Investment Holding Ltd | Real estate | 2021 |
| C Ramos Limited | Health & social care | 2013 |
| C&E by Constantine and Elena Limited | Transport & logistics | 2025 |
| C.A.G. (Decorating) Limited | Construction | 1996 |
| C.Brandiu Ltd | Construction | 2023 |
| Caaveiry Ltd | Wholesale & retail | 2014 |
| Cader Cleaning Limited | Wholesale & retail | 2026 |
| Cafe Savoy Ltd | Hospitality | 2018 |
| Caldera Ltd | Professional & scientific | 2022 |
| Call a Bowl Limited | Hospitality | 2025 |
| Callisto Marine Ltd | Extraterritorial | 2017 |
| Camila ANA Ltd | Hospitality | 2025 |
| Campbell Housing Limited | Real estate | 2026 |
| Campus UK Educational Services Ltd | Professional & scientific | 2015 |
| Candiotto Solutions Ltd | Construction | 2025 |
| Canela Village CIC | Education | 2023 |
| Caniclub Ltd | Information & communication | 2024 |
| Capi Couriers Ltd | Transport & logistics | 2025 |
| Capital Suppliers Ltd | Wholesale & retail | 2025 |
| Captain Property Ltd | Real estate | 2025 |
| Cara Bendon Brand Consultancy Ltd | Professional & scientific | 2022 |
| Carclo Diagnostic Solutions Limited | Manufacturing | 2011 |
| Carclo Group Services Limited | Extraterritorial | 1911 |