| Bishops Cleeve Italian Ltd | Real estate | 2023 |
| Bishops Cleeve Pizza Limited | Hospitality | 2021 |
| Bishops Cleeve Preschool Limited | Health & social care | 2019 |
| Bishops Meadow Management Limited | Households | 1992 |
| Bishops Solutions Limited | Professional & scientific | 2012 |
| BIT Brain Software Limited | Information & communication | 2006 |
| Bites Babywear Limited | Wholesale & retail | 2015 |
| Bitesize Adventures Ltd | Hospitality | 2014 |
| Bitsan Limited | Information & communication | 2020 |
| Bitter Lemon Creative Limited | Professional & scientific | 2015 |
| Bizdge Limited | Wholesale & retail | 2021 |
| Bizinexa Ltd | Information & communication | 2026 |
| Bizsystems Limited | Professional & scientific | 2011 |
| Bizzarc Ltd | Information & communication | 2025 |
| BJ Housing Limited | Real estate | 2024 |
| Bjds Associates Limited | Wholesale & retail | 2017 |
| BJM Enterprises Limited | Administrative & support | 2006 |
| BK Book-Keeping & Accountancy Services Ltd | Professional & scientific | 2010 |
| BKB Project Services Ltd | Construction | 2015 |
| BKC Limited | Financial services | 2024 |
| Bkha Ltd | Real estate | 2021 |
| Black Book Design Collective Ltd | Arts & recreation | 2025 |
| Black Carat Limited | Arts & recreation | 2022 |
| Black Cedar Limited | Administrative & support | 1995 |
| Black Gold Café Ltd | Hospitality | 2016 |
| Blackbose Ltd | Professional & scientific | 2025 |
| Blackfinch Adaptations PLC | Financial services | 2018 |
| Blackfinch Asset Management Limited | Financial services | 2018 |
| Blackfinch Corporate Services Limited | Financial services | 2004 |
| Blackfinch Energy Transition Nominees Limited | Financial services | 2024 |
| Blackfinch Financial Limited | Financial services | 2005 |
| Blackfinch Group Limited | Financial services | 2005 |
| Blackfinch Holdings Limited | Financial services | 2019 |
| Blackfinch Investments Limited | Financial services | 1992 |
| Blackfinch Nominees Limited | Financial services | 2013 |
| Blackfinch Spring VCT PLC | Financial services | 2019 |
| Blackfinch Trustees Limited | Financial services | 2018 |
| Blackfinch Ventures Nominees Limited | Financial services | 2018 |
| Blackfort Global Ltd | Financial services | 2025 |
| Blackhole Security Ltd | Information & communication | 2023 |
| Blacksmiths Group Consulting Ltd | Professional & scientific | 2025 |
| Blacksmiths Group Global Limited | Professional & scientific | 2023 |
| Blacksmiths Group Ltd | Information & communication | 2015 |
| Blackthorn Holdings Limited | Real estate | 1991 |
| Blackwood EMC Ltd | Extraterritorial | 2003 |
| Bladeroom Group Limited | Information & communication | 2008 |
| Bladeroom Holdings Limited | Professional & scientific | 2022 |
| Bladeroom Residential Limited | Information & communication | 2007 |
| Blah 3 Limited | Wholesale & retail | 2024 |
| Blair Homes Ltd | Real estate | 2020 |
| Blair Investment Group Limited | Financial services | 2026 |
| Blakark Ltd | Arts & recreation | 2002 |
| Blake Assets Ltd | Other services | 2023 |
| Blake Events Limited | Other services | 2011 |
| Blake Health Ltd | Health & social care | 2023 |
| Blakes Fields Ltd | Financial services | 2026 |
| Blakeway Heritage Holdings Limited | Real estate | 2024 |
| Blanc Barbershop Limited | Other services | 2026 |
| Blaze Clothing Ltd | Wholesale & retail | 2022 |
| Bleasby (2000) Limited | Households | 1999 |
| Bleasby House (Managers) Limited | Households | 1973 |
| Blenheim Design Limited | Professional & scientific | 2008 |
| Bletchley Bespoke Carpentry & Joinery Limited | Manufacturing | 2024 |
| Bleu Blanc Rouge Food and Drink Ltd | Wholesale & retail | 2024 |
| Bleu Hair and Beauty Salon Ltd | Other services | 2020 |
| Blincoe Financial Planning Limited | Professional & scientific | 2023 |
| Blink Medical Limited | Wholesale & retail | 2004 |
| Blink Tyler Limited | Financial services | 2008 |
| Bliss Apartments (Trading Company) Limited | Real estate | 2013 |
| Blissful Bathrooms Ltd | Wholesale & retail | 2014 |
| Blonde Optometry Ltd | Professional & scientific | 2025 |
| Blondiez Ltd | Arts & recreation | 2023 |
| Bloom and Cadogan Ltd | Other services | 2003 |
| Bloom Drop Ltd | Wholesale & retail | 2026 |
| Bloom Embroidery Academy Ltd | Education | 2026 |
| Bloomers Flowers Limited | Wholesale & retail | 2022 |
| Bloomska Ltd | Real estate | 2020 |
| Bloomska Trading Limited | Real estate | 2024 |
| Blossom Leasing Limited | Financial services | 2009 |
| Blounce Farms Limited | Agriculture & fishing | 1997 |
| Blow (UK) Limited | Other services | 2000 |
| BLU Developments Ltd | Construction | 2021 |
| BLU Shop Ltd | Wholesale & retail | 2026 |
| Blu-Fish Ltd | Construction | 2007 |
| Bluclarity Limited | Administrative & support | 2025 |
| Blue 52 Consulting Limited | Administrative & support | 2011 |
| Blue and Blue Limited | Arts & recreation | 2017 |
| Blue Bear Talent Ltd | Administrative & support | 2022 |
| Blue Boar Court Limited | Real estate | 2006 |
| Blue Mekong Octopus Services Ltd | Information & communication | 2021 |
| Blue Muse Productions Limited | Information & communication | 2023 |
| Blue Orange Developments Limited | Construction | 2018 |
| Blue Oval Vehicle Services Ltd | Wholesale & retail | 2024 |
| Blue Parrot Ltd | Arts & recreation | 2009 |
| Blue Parrot Productions Ltd | Arts & recreation | 2010 |
| Blue Squirrel Ltd | Real estate | 2024 |
| Blue Tang Marketing Limited | Professional & scientific | 2006 |
| Blue Temple Holding Limited | Financial services | 2025 |
| Blue Temple Limited | Wholesale & retail | 2001 |
| Blue Wing Limited | Transport & logistics | 1975 |