| Bixie Group Ltd | Manufacturing | 2017 |
| Bizarseller. Ltd | Wholesale & retail | 2025 |
| BK Catering Services Ltd | Hospitality | 2025 |
| BKI Finance Limited | Professional & scientific | 2018 |
| BL Safety Solutions Ltd | Construction | 2025 |
| Black Cat Solutions Ltd | Administrative & support | 2010 |
| Black Company MD Ltd | Transport & logistics | 2024 |
| Black Doves Pro Ltd | Other services | 2025 |
| Bladon Plumbing & Heating Limited | Construction | 2005 |
| Blakes Properties Limited | Real estate | 1998 |
| Blessedcaresolution Ltd | Health & social care | 2022 |
| Blinding Bi-Fold Doors Limited | Construction | 2017 |
| Blooming Aura Ltd | Wholesale & retail | 2026 |
| Bloomsbury & Sandringham Freehold Limited | Households | 2017 |
| Blue NRG Ltd | Construction | 2019 |
| Blue Seas Adjusters Limited | Financial services | 2005 |
| Blue Vision Technologies Limited | Information & communication | 2022 |
| BLUE8 Services Limited | Transport & logistics | 2020 |
| Blusoft Limited | Information & communication | 2015 |
| BM & RG Limited | Wholesale & retail | 2004 |
| BMM Surgical Services Ltd | Health & social care | 2024 |
| BMS & BPR Consulting Limited | Transport & logistics | 2017 |
| BNE Bookkeepers Ltd | Professional & scientific | 2018 |
| BNE Merchants Ltd | Information & communication | 2021 |
| BNE Painting Specialists Ltd | Construction | 2023 |
| BNE Supplies Ltd | Wholesale & retail | 2021 |
| BNE Traders Limited | Wholesale & retail | 2020 |
| BNJ Luxury Ltd | Administrative & support | 2025 |
| Bnmm Holdings Ltd | Professional & scientific | 2023 |
| Bnmt Limited | Health & social care | 2019 |
| BNT Property Group Limited | Real estate | 2019 |
| Boatside Investments | Financial services | 2021 |
| Bockings Developments Ltd | Construction | 2024 |
| Bodi London Ltd | Wholesale & retail | 2019 |
| Body IQ Coaching Limited | Administrative & support | 2011 |
| Bodyworks Massage Therapy Limited | Health & social care | 2004 |
| Bogdan Surdu Limited | Transport & logistics | 2019 |
| Bolt Interiors Ltd | Construction | 2016 |
| Bolt IT Site Solutions Ltd | Construction | 2020 |
| Bond Construction HMO Specialists Ltd | Construction | 2019 |
| Bonza Care Ltd | Health & social care | 2013 |
| Booba Cloud Ltd | Administrative & support | 2026 |
| Bookphoria Limited | Wholesale & retail | 2010 |
| Boris Lions Ltd | Transport & logistics | 2020 |
| Borister Ltd | Construction | 2014 |
| Borzy Ltd | Professional & scientific | 2026 |
| Botley Manor Services Limited | Administrative & support | 2016 |
| Boxtxi Limited | Extraterritorial | 2017 |
| BPAS1919 Limited | Real estate | 2020 |
| Bpis Electricals Limited | Construction | 2012 |
| BPM Fitness Limited | Arts & recreation | 2018 |
| Bradley James Hair Ltd | Other services | 2018 |
| Bradmore Green Limited | Hospitality | 2024 |
| Bradmore House Management Limited | Real estate | 2013 |
| Bradmore Industrial Limited | Real estate | 2019 |
| Brainbox Labs Ltd | Professional & scientific | 2023 |
| Bramble Consulting Limited | Extraterritorial | 2020 |
| Bramley-Brett Holdings Limited | Financial services | 2022 |
| BRAND2PROMOTE Ltd | Wholesale & retail | 2012 |
| Brandfalloden-Way Ltd | Real estate | 2025 |
| Brass Tacks Fittings Limited | Manufacturing | 1999 |
| Bratsk Limited | Professional & scientific | 2021 |
| Braveyt Ltd | Transport & logistics | 2022 |
| Bredwardine Investments Limited | Financial services | 2022 |
| Briantech Limited | Wholesale & retail | 2025 |
| Briary Energy Limited | Professional & scientific | 2016 |
| Brickstone Renovation Limited | Construction | 2013 |
| Bridel Mews Management Limited | Households | 1999 |
| Bridgestone Consulting Limited | Real estate | 2024 |
| Bright Manor Limited | Real estate | 2003 |
| Bright River Ltd | Construction | 2019 |
| Brightfeel Consulting Ltd | Professional & scientific | 2026 |
| Brightroute Education UK Ltd | Professional & scientific | 2026 |
| Brightside Community Preschool CIC | Health & social care | 2022 |
| Brightside Preschool (Hertford) CIC | Health & social care | 2026 |
| Brightside Preschool Ltd | Health & social care | 2022 |
| Brightsun Choice Limited | Wholesale & retail | 2022 |
| Brika Hand Car Wash Ltd | Administrative & support | 2023 |
| Brilliance Law Academy UK Ltd | Education | 2025 |
| Brilliance Solicitors Ltd | Professional & scientific | 2018 |
| Brilliant Star Ltd | Construction | 2018 |
| Brillianz International Ltd | Manufacturing | 2012 |
| Brimu Ventures Ltd | Information & communication | 2024 |
| Brinham Partners Limited | Transport & logistics | 2025 |
| Brit Aqua Salt Limited | Construction | 2025 |
| Britechx Systems Ltd | Information & communication | 2025 |
| Brits Autos Ltd | Wholesale & retail | 2024 |
| Britten Enterprises Ltd | Financial services | 2013 |
| Britz Global Limited | Public administration | 2022 |
| Broad Minded Events Limited | Arts & recreation | 2007 |
| Broadcure Limited | Health & social care | 2022 |
| Brokenmoon Ltd | Arts & recreation | 2026 |
| Bromwall Data Services Ltd | Information & communication | 1977 |
| Bromwall Limited | Financial services | 1974 |
| Bronze Babes Ltd | Other services | 2017 |
| Brooke View Limited | Public administration | 2018 |
| Brookfield Court Residents Association Limited | Households | 1996 |
| Brookgate Construction Limited | Construction | 2024 |
| Brooklands Healthtrack Limited | Professional & scientific | 1994 |
| Brookmans Bakery Limited | Wholesale & retail | 2013 |