| Block and Lettings Maintenance Ltd | Construction | 2022 |
| Blommestein Ltd | Information & communication | 2023 |
| Bloom Gardens Ltd | Wholesale & retail | 2025 |
| Blooming COW Ltd | Wholesale & retail | 2026 |
| Blooming Hub Limited | Wholesale & retail | 2025 |
| Bltng Ltd | Other services | 2014 |
| Blue Architects Ltd | Professional & scientific | 2003 |
| Blue Dine Ltd | Hospitality | 2025 |
| Blue Feather Trading Limited | Other services | 2012 |
| Blue Gunner Limited | Arts & recreation | 2015 |
| Blue Horizon Atelier Ltd | Wholesale & retail | 2025 |
| Blue Light Aesthetics Limited | Other services | 2025 |
| Blue Panda PR Limited | Extraterritorial | 2017 |
| Blue PAW Investments Ltd | Real estate | 2025 |
| Blue Penguin Consulting Limited | Professional & scientific | 2010 |
| Blue Plume Academy Limited | Professional & scientific | 2025 |
| Blue Range Consulting Limited | Construction | 2022 |
| Blue Star Medical Consulting Limited | Health & social care | 2017 |
| Blue Stone Christmas Ltd | Wholesale & retail | 2019 |
| Blue Stone Plant Hire Ltd | Administrative & support | 2019 |
| Blue X Adventure Ltd | Wholesale & retail | 2019 |
| Blueai Ltd | Information & communication | 2026 |
| Bluebell Rise Management Company Limited | Households | 2026 |
| Bluebinaries Engineering and Solutions Ltd | Professional & scientific | 2018 |
| Blueprint Worldwide Events Ltd | Arts & recreation | 2010 |
| Blueprinting Limited | Other services | 2018 |
| Blueseal Plumbing Ltd | Construction | 2025 |
| Bluetrundle Limited | Information & communication | 2010 |
| Bluu Consultancy Ltd | Professional & scientific | 2014 |
| Blyth Care Ltd | Administrative & support | 2018 |
| BMH Roofing & Leadwork Limited | Construction | 2026 |
| Bnpm 64 Limited | Other services | 2020 |
| Boardpiece Drylining Ltd | Construction | 2026 |
| Boban Sebastian Ltd | Professional & scientific | 2025 |
| BOC Chile Holdings Limited | Professional & scientific | 1994 |
| BOC Distribution Services Limited | Extraterritorial | 1966 |
| BOC Gases Limited | Professional & scientific | 1991 |
| BOC Healthcare Limited | Professional & scientific | 1997 |
| BOC Helex | Professional & scientific | 1966 |
| BOC Investment Holdings Limited | Professional & scientific | 1996 |
| BOC Investments NO.1 Limited | Professional & scientific | 1996 |
| BOC Investments NO.5 | Professional & scientific | 2001 |
| BOC Korea Holdings Limited | Professional & scientific | 1989 |
| BOC Limited | Manufacturing | 1938 |
| BOC Netherlands Holdings Limited | Professional & scientific | 1990 |
| BOC Nominees Limited | Extraterritorial | 1964 |
| BOC Pensions Limited | Professional & scientific | 1968 |
| BOC Retirement Benefits Scheme Trustees Limited | Professional & scientific | 1997 |
| BOC Trustees Limited | Education | 2014 |
| Boda Capital Limited | Financial services | 2014 |
| Boden Property Services Ltd | Administrative & support | 2024 |
| Bodhi Design Ltd | Professional & scientific | 2018 |
| Bodiactive Limited | Real estate | 2012 |
| Body and Beauty Studio Limited | Health & social care | 2018 |
| Bodylinx Limited | Health & social care | 2013 |
| Bodyshop Supply Limited | Wholesale & retail | 2025 |
| Bogdan Fantastic Ltd | Construction | 2018 |
| Bold Electrification UK Ltd | Professional & scientific | 2021 |
| Bold Valuable Technology Limited | Administrative & support | 2014 |
| Bole Aller House Limited | Health & social care | 2001 |
| Bole Construction Limited | Construction | 2010 |
| Bolebrook Polo LLP | | 2009 |
| Bond of London Limited | Professional & scientific | 2011 |
| Bonkers Properties Limited | Real estate | 2017 |
| Bontempo Garden Services Ltd | Administrative & support | 2017 |
| Bookingiant Ltd | Administrative & support | 2025 |
| Bookkeeping & Accounts AG Ltd | Professional & scientific | 2019 |
| Boomerang Taxis Ltd | Transport & logistics | 1993 |
| Boormans Limited | Wholesale & retail | 2004 |
| Boost AI Ltd | Information & communication | 2018 |
| Boothman Design Limited | Information & communication | 2015 |
| Boriksa Ltd | Construction | 2014 |
| Borkay Investments Ltd | Real estate | 2025 |
| Borme Developments Limited | Construction | 2010 |
| Born Wild Play Cafe Limited | Hospitality | 2025 |
| Borowiecki Properties Ltd | Real estate | 2025 |
| Boston Design Limited | Information & communication | 2026 |
| Botanic Life Ltd | Extraterritorial | 2025 |
| Botany Barns Management Company Limited | Real estate | 2012 |
| Boucton Vettori (UK) Limited | Wholesale & retail | 2013 |
| Boughton Hall Avenue Residents' Association Limited | Households | 1963 |
| Bounce Property Ltd | Real estate | 2024 |
| Bouncy Bouncy Back Limited | Arts & recreation | 2025 |
| Bowerbox Ltd | Wholesale & retail | 2021 |
| Bowland Recruitment Limited | Administrative & support | 2021 |
| Boxey Ltd | Information & communication | 2024 |
| Boxgrove Electrical Contractors Ltd | Construction | 2021 |
| Boxtech Cloud Consulting Ltd | Information & communication | 2023 |
| Boz's Fruit & VEG Ltd | Wholesale & retail | 2014 |
| BP BAT Limited | Construction | 2014 |
| Brackenbury's Ltd | Other services | 2010 |
| Brackenwood Homes Ltd | Construction | 2021 |
| Bracknell Heating and Plumbing Supplies Ltd | Wholesale & retail | 2017 |
| Bradley Joyce Technical Ltd | Professional & scientific | 2024 |
| Bradspace Ltd | Professional & scientific | 2015 |
| Brailsford Limited | Households | 2025 |
| Brain Injury IS Big | Health & social care | 2011 |
| Brainy Black Ltd | Financial services | 2024 |
| Bramah HR Ltd | Administrative & support | 2021 |
| Bramah Safeguarding CIC | Professional & scientific | 2025 |