| BR Health & Wellness Ltd | Health & social care | 2022 |
| Bradcom Ltd | Information & communication | 2026 |
| Braddon Maxwell Limited | Households | 2009 |
| Bradshaw Investments Limited | Professional & scientific | 2014 |
| Brainsell Limited | Professional & scientific | 2001 |
| Braintree Hotel Limited | Hospitality | 2009 |
| Brainworkz CIC | Health & social care | 2025 |
| Brake Technical Services Limited | Professional & scientific | 2022 |
| Braking Solutions Limited | Extraterritorial | 2002 |
| Bramble & Moss Ltd | Wholesale & retail | 2011 |
| Brand Trademark and IP Holdings Limited | Financial services | 2024 |
| Brandeer Design Ltd | Professional & scientific | 2017 |
| Brandram Mews Management Limited | Households | 1997 |
| Brcl Ltd | Transport & logistics | 2021 |
| Breadcrumbs Game Ltd | Arts & recreation | 2017 |
| Breaking Media Limited | Information & communication | 2014 |
| Breakwatermarketing Ltd | Professional & scientific | 2019 |
| Breckenbrough Farm Limited | Agriculture & fishing | 2018 |
| Bredian Properties Limited | Real estate | 1960 |
| Bremsen Technik (UK) Limited | Wholesale & retail | 2001 |
| Bremsen Technik Holdings Ltd | Financial services | 2013 |
| Bremsen Technik Reman Limited | Manufacturing | 2016 |
| Brendan Tracey Architects Ltd | Professional & scientific | 2023 |
| Brentford Gallery & Studios Ltd | Arts & recreation | 2023 |
| Brewers Angel Limited | Hospitality | 2012 |
| Brewers Dray Limited | Hospitality | 2012 |
| Brewferm Ltd | Manufacturing | 1997 |
| Brian Hutchinson Limited | Agriculture & fishing | 2019 |
| Brian Jones Limited | Professional & scientific | 2001 |
| Bridge Dales Transport Ltd | Transport & logistics | 2021 |
| Bridge Dental Centre Limited | Health & social care | 2008 |
| Bridgehead Housing Limited | Real estate | 2017 |
| Bridges Group Ltd | Financial services | 2025 |
| Bridgestone Estates Ltd | Real estate | 2015 |
| Bridgewater Recruitment Solutions Limited | Administrative & support | 2020 |
| Briggs Solutions Ltd | Professional & scientific | 2018 |
| Bright Eyes Ophthalmic Care Ltd | Health & social care | 2018 |
| Bright Path Ishayas C.I.C | Health & social care | 2009 |
| Brighton International UK Limited | Wholesale & retail | 2015 |
| Brightstar Partners Ltd | Financial services | 2002 |
| Brightwell and Partners LLP | | 2025 |
| Brigown Holdings Limited | Financial services | 2021 |
| Brigown Limited | Hospitality | 2021 |
| Brincan Ltd | Professional & scientific | 2012 |
| Bristol Clare Street Limited | Households | 2023 |
| Bristow Land Consultants Limited | Real estate | 2003 |
| Broadberry Developments Ltd | Construction | 2021 |
| Broadberry Investments Ltd | Real estate | 2021 |
| Broadberry Management Limited | Information & communication | 2011 |
| Broader Roots Limited | Education | 2025 |
| Broadlands Court (KEW Residents Association) Limited | Professional & scientific | 1994 |
| Broadware Limited | Information & communication | 2008 |
| Brollachaun Holdings Limited | Financial services | 2022 |
| Brompton Business Growth Ltd | Professional & scientific | 2020 |
| Brompton Lakes Limited | Hospitality | 2016 |
| Brompton Lakes Management Company Limited | Real estate | 2022 |
| Brooklands Technology Limited | Extraterritorial | 2021 |
| Brookleigh Consulting Limited | Professional & scientific | 2008 |
| Brookleigh Riding Centre Limited | Arts & recreation | 1999 |
| Brookline (Baslow) Limited | Real estate | 2019 |
| Brookline (Ranmoor) Limited | Real estate | 2022 |
| Brookline (Suffolk) Limited | Real estate | 2019 |
| Brookline Charlie Investments Limited | Real estate | 2017 |
| Brookline Charlie Limited | Arts & recreation | 2014 |
| Brookline Shoreham Street Limited | Real estate | 2023 |
| Brookline Whitby Limited | Real estate | 2017 |
| Browny Blue Limited | Information & communication | 2012 |
| Browson Design & Build Ltd | Construction | 2017 |
| Brumby Media Group Ltd | Information & communication | 2018 |
| Brychta Software Ltd | Information & communication | 2026 |
| BSA Electrical Limited | Construction | 2020 |
| Bspoke Tours Limited | Administrative & support | 2014 |
| Btek Robots Ltd | Information & communication | 2024 |
| Buchanan Cost Consultancy Ltd | Professional & scientific | 2021 |
| Buckley Smith Ltd | Professional & scientific | 2014 |
| Buckley Smith Property Ltd | Real estate | 2023 |
| Buckley-Reynolds Limited | Professional & scientific | 2024 |
| Buffalo Music Limited | Arts & recreation | 1983 |
| Buffalo Tours UK Limited | Administrative & support | 2010 |
| Buffet Properties Limited | Real estate | 2021 |
| Build and Prosper Construction Ltd | Construction | 2025 |
| Build Kind Ltd | Information & communication | 2025 |
| Building Clinic Ltd | Construction | 2021 |
| Bulk Powder Terminals Limited | Transport & logistics | 2015 |
| Bumble BEE Creations Limited | Professional & scientific | 2002 |
| Burford Homes Limited | Real estate | 2014 |
| Burger Junction Limited | Hospitality | 2008 |
| Burleigh Wood Property Management Limited | Real estate | 2015 |
| Bushfare Limited | Construction | 1980 |
| Business Professional Training Ltd | Education | 2016 |
| Business Solution Limited | Administrative & support | 2003 |
| Butte Brothers Ltd | Wholesale & retail | 2022 |
| Butter Beans Limited | Hospitality | 2013 |
| BY Technology Consulting Ltd | Information & communication | 2026 |
| BY Tilly Ltd | Manufacturing | 2024 |
| BYB Construction Ltd | Construction | 2024 |
| BYE Disc Ltd | Manufacturing | 2026 |
| Byrley Ltd | Financial services | 2013 |
| Byrnes Soler & Co Limited | Professional & scientific | 1996 |
| Bysoee Ltd | Information & communication | 2025 |