| Brinkcliffe Gardens Management Company Limited | Households | 1999 |
| Brinton Gustar Freehold Limited | Real estate | 2011 |
| Brisq Metrology Ltd | Professional & scientific | 2015 |
| Bristol Bread Ltd | Manufacturing | 2024 |
| Bristol Catering Entertainment Ltd | Hospitality | 2023 |
| Bristol Conservatory Upgrades Limited | Construction | 2015 |
| Bristol Global Supply Ltd | Wholesale & retail | 2025 |
| Bristol Lofts Ltd | Real estate | 2019 |
| Bristol Motors Direct Ltd | Wholesale & retail | 2023 |
| Bristol Touch Ltd | Arts & recreation | 2017 |
| British Amateur Gymnastics Association(The) | Other services | 1982 |
| British Gymnastics England Limited | Arts & recreation | 2008 |
| British Gymnastics Foundation | Education | 2014 |
| British Mount Everest North Ridge Expedition Ltd | Extraterritorial | 2010 |
| Briton Estates Ltd | Real estate | 2024 |
| Britt Form a Ltd | Administrative & support | 2020 |
| Brittannia Stores Newport Ltd | Wholesale & retail | 2020 |
| Broad Close Limited | Households | 2024 |
| Broadhall (Coldra Woods) Limited | Hospitality | 2016 |
| Broadstone Media Ltd | Extraterritorial | 2018 |
| Broadstreet Common Cars Ltd | Wholesale & retail | 2022 |
| Broadwayoaks Ltd | Transport & logistics | 2025 |
| Brockton Care Limited | Health & social care | 2012 |
| Brockton Training Ltd | Education | 2024 |
| Broken Doll Images Ltd | Professional & scientific | 2018 |
| Broken Lines Publishing Limited | Arts & recreation | 2019 |
| Brollyman Productions Limited | Information & communication | 2014 |
| Brook Hill (NO.2) Management Limited | Households | 1992 |
| Brook House IOW Services Limited | Energy | 2013 |
| Brook Mead Management Company Limited | Households | 1980 |
| Brooke (IW) Limited | Wholesale & retail | 2022 |
| Brookey (I W) Limited | Wholesale & retail | 2017 |
| Brookmead Limited | Construction | 2016 |
| Brookmead Property Ltd | Real estate | 2017 |
| Brookstreet Pictures Limited | Information & communication | 2021 |
| Broom Homes Limited | Construction | 2018 |
| Broomhomes River Limited | Construction | 2018 |
| Broseley Fireclay Company Limited | Mining & quarrying | 2004 |
| Browne Electrical Services Ltd | Construction | 2018 |
| Browse Beauty Ltd | Other services | 2025 |
| Bruce Whitear Consulting Ltd | Administrative & support | 2023 |
| Bruce Woodhead Limited | Real estate | 1976 |
| Bruminati Ltd | Information & communication | 2022 |
| Brunel Steel Buildings Ltd | Manufacturing | 2025 |
| Brunel Steel Services Limited | Manufacturing | 1977 |
| Brwnt Food Ltd | Hospitality | 2025 |
| Brymbo Developments Limited | Other services | 1968 |
| Brymbo Property Co Ltd | Construction | 2023 |
| Bryn CI Properties Ltd | Real estate | 2024 |
| Bryn Quarry Limited | Extraterritorial | 1996 |
| Brynhaulog Limited | Health & social care | 2004 |
| Brynmawr United F.C. CIC | Arts & recreation | 2025 |
| BSC Management IW Limited | Real estate | 2009 |
| BSG Ecology Ltd | Professional & scientific | 2019 |
| BSG Ecology Trustees Limited | Professional & scientific | 2023 |
| Bsmpubco Ltd | Hospitality | 2025 |
| BSP Retail Group Limited | Wholesale & retail | 2022 |
| Bssh Image Limited | Professional & scientific | 2018 |
| BT Care Ltd | Health & social care | 2021 |
| BT Consulting Ltd | Professional & scientific | 2022 |
| BT Plant Services Ltd | Manufacturing | 2015 |
| Bubble Bath & Bodyworks Ltd | Wholesale & retail | 2019 |
| Bubumaru Limited | Wholesale & retail | 2021 |
| Budbridge Estates Limited | Construction | 2012 |
| Budbridge Property Investments Limited | Real estate | 2017 |
| Buddlebrook Education Services Ltd | Professional & scientific | 2023 |
| Buddy Properties Limited | Real estate | 2021 |
| Budget Accommodation Limited | Hospitality | 2025 |
| Budgetwholesale Limited | Wholesale & retail | 2022 |
| Buggy Hire Limited | Professional & scientific | 2008 |
| Buggy Hire UK Limited | Professional & scientific | 2008 |
| Build on Architects Limited | Professional & scientific | 2021 |
| Build Your Wellbeing Ltd | Health & social care | 2018 |
| Builder Pro Base Ltd | Construction | 2025 |
| Building Integrated Photovoltaics Limited | Manufacturing | 2013 |
| Buildsworth Limited | Construction | 2018 |
| Buildtek Construction Ltd | Construction | 2014 |
| Bukharis Ltd | Health & social care | 2022 |
| Bukka Bites Ltd | Wholesale & retail | 2023 |
| Bull Project Group Limited | Real estate | 2024 |
| Bullen Trading Co Ltd | Wholesale & retail | 2009 |
| Bullen Village Management Company Limited | Households | 2007 |
| Bullforce Scaffolding Ltd | Construction | 2025 |
| Bumba Zonkie Limited | Manufacturing | 1999 |
| Bumblebee Mortgages Limited | Financial services | 2020 |
| Bump Boobs Babi Ltd | Health & social care | 2021 |
| Bump to Birth and Beyond Ltd | Wholesale & retail | 2023 |
| BUN Symes Contracting Limited | Agriculture & fishing | 2004 |
| Burger Lions Limited | Hospitality | 2022 |
| Burglar Bar Collection Ltd | Wholesale & retail | 2023 |
| Burleigh House Day Nursery Ltd | Health & social care | 2026 |
| Burlesque Holdings Ltd | Real estate | 2022 |
| Burmont Ltd | Wholesale & retail | 2020 |
| Burns 688 Ltd | Arts & recreation | 2020 |
| Burrium Gate Management Company Limited | Households | 2010 |
| Burron Engineering Limited | Construction | 2023 |
| Burron Property Developments Ltd | Real estate | 2026 |
| Burrows Property Holding Limited | Real estate | 2025 |
| Burrows PUB Management Limited | Hospitality | 2013 |
| BUS Station Heel Bar Limited | Wholesale & retail | 2004 |