| Belden UK Limited | Manufacturing | 1993 |
| Belle Coachworks Limited | Manufacturing | 2000 |
| Bellina Ipswich | | 1985 |
| Bellisimos Academy Ltd. | Other services | 2016 |
| Bellstone Residential Care Ltd | Hospitality | 2002 |
| BEN Barrow Property Ltd | Real estate | 2021 |
| BEN Nevis Homes Ltd | Construction | 2018 |
| Bendall & Osborne Plumbing & Heating Ltd | Construction | 2001 |
| Bennett & Bennett Accounting Consultancy Limited | Professional & scientific | 2003 |
| Berita Limited | Administrative & support | 2016 |
| Berridge's Limited | Wholesale & retail | 1994 |
| Berry Bliss Ltd | Hospitality | 2007 |
| Besheh Meesheh Films Ltd | Information & communication | 2023 |
| Bespoke by Stephanie Ltd | Manufacturing | 2019 |
| Bestlink Steam Limited | Wholesale & retail | 2025 |
| Besund Limited | Health & social care | 2012 |
| Betrygg Limited | Manufacturing | 2015 |
| Beyond Compare Global Ltd | Wholesale & retail | 2023 |
| Bickers & Dodds Builders Limited | Construction | 2006 |
| Bideawhile 153 Limited | Real estate | 1993 |
| Bigley Property Services Ltd | Real estate | 2022 |
| Biketrace Limited | Wholesale & retail | 2020 |
| Bill Bulstrode (Framlingham) Ltd | Wholesale & retail | 2002 |
| Bimg Limited | Financial services | 2014 |
| Bina Enterprise Ltd | Hospitality | 2026 |
| Bineri Limited | Energy | 2005 |
| Binks of Beccles Ltd | Wholesale & retail | 2006 |
| Bittern Green Management Limited | Professional & scientific | 2001 |
| BK CONSTRUCTION1 Limited | Construction | 2016 |
| BK Property Group Limited | Real estate | 2025 |
| Blackthorn Books Limited | Information & communication | 2022 |
| Blade Inclusive Salon Ltd | Other services | 2006 |
| Bliss Beyond Limited | Other services | 2024 |
| Bloom Educational Services Ltd | Education | 2023 |
| Bloom Sourcing Ltd | Wholesale & retail | 2022 |
| Blue Lizard Equestrian Ltd | Wholesale & retail | 2006 |
| Bluedeals Online Limited | Wholesale & retail | 2025 |
| Bluesources Ltd | Wholesale & retail | 2019 |
| Blusystems Ltd | Information & communication | 2019 |
| BMC Plumbing & Heating Ltd | Construction | 2026 |
| Bobby's Bargains Limited | Wholesale & retail | 2020 |
| Boggis Electrical Limited | Construction | 1940 |
| Bonnevida Limited | Wholesale & retail | 2018 |
| Booty Estates Ltd | Construction | 2005 |
| Boris Fitness Ltd | Arts & recreation | 2023 |
| Bosch Lawn and Garden Limited | Manufacturing | 1995 |
| Bosmere GAS Services Limited | Other services | 2003 |
| Botanu Limited | Manufacturing | 2023 |
| Bower Fuller Limited | Professional & scientific | 2003 |
| Boxing Highs Limited | Information & communication | 2020 |
| Boxofwine Limited | Wholesale & retail | 2003 |
| Braat Drylining Ltd | Construction | 2022 |
| Bradleys (Stowmarket) Limited | Manufacturing | 1936 |
| Bradonwell Limited | Mining & quarrying | 2006 |
| Brafe Engineering Limited | Manufacturing | 1966 |
| Brafe Trustee Limited | Extraterritorial | 2005 |
| Brands by Millennials Ltd | Wholesale & retail | 2024 |
| Brandside Investments Limited | Extraterritorial | 2002 |
| Breakaway Tackle Development Co.Limited | Wholesale & retail | 1972 |
| Breeze Store Limited | Wholesale & retail | 2023 |
| Brian's Maintenance Services Limited | Construction | 2005 |
| Bridgeway Accountants & Co Ltd | Professional & scientific | 2026 |
| Bridgewell Housing Ltd | Real estate | 2025 |
| Bright Financial Planning Limited | Financial services | 2006 |
| Brighter Skies Company Limited | Wholesale & retail | 2018 |
| Brightsway Ltd | | 1998 |
| Bristar Machinery (UK) Limited | Wholesale & retail | 1986 |
| Britaniashaw Investments Limited | Extraterritorial | 2001 |
| Brityon Supply Co Limited | Wholesale & retail | 2025 |
| Broadside Customs Clearance Agency Ltd | Transport & logistics | 2007 |
| Broadstreet Great Western Holdings Limited | Professional & scientific | 2024 |
| Broadwater Mouldings Limited | Manufacturing | 1971 |
| Brockworth Developments Limited | Real estate | 2005 |
| Bronte Blinds Ltd | Construction | 2023 |
| Brownoak (Eastern) Assured Tenancies Limited | Real estate | 1993 |
| Browns Marine Consultancy Limited | Professional & scientific | 2007 |
| Bryan Procurement Services Ltd | Professional & scientific | 2015 |
| BSY3D Limited | Wholesale & retail | 2021 |
| BT Shipping Ltd | Transport & logistics | 2022 |
| Bubble Tea Investments Ltd | Hospitality | 2022 |
| Bulmer Brick and Tile Company Limited(The) | Agriculture & fishing | 1936 |
| Bumbles Ltd | Wholesale & retail | 2025 |
| Bumpstead Garden Pizza Ltd | Hospitality | 1964 |
| Bunnies Day Care Limited | Education | 2005 |
| Burrows and Watson Limited | Construction | 2005 |
| Bury Company Services Limited | Extraterritorial | 1993 |
| Bush Boake Allen Enterprises Limited | Professional & scientific | 1996 |
| Bush Boake Allen Holdings (U.K.) Limited | Professional & scientific | 1982 |
| Bush Boake Allen Limited | Professional & scientific | 1897 |
| Bushells Bakery Limited | Manufacturing | 1992 |
| Business Assistants Ltd | Professional & scientific | 2020 |
| Business Autopilot Ltd | Professional & scientific | 2018 |
| Busiyard International Limited | Financial services | 2024 |
| Buttercup Finance Ltd | Professional & scientific | 2019 |
| Buttermarket Barbers Ltd | Other services | 2020 |
| BY Choice Limited | Real estate | 2004 |
| Bychurch Limited | Administrative & support | 2024 |
| Bycullah Time-Share Limited | Hospitality | 1982 |
| Bynshoppin Limited | Information & communication | 2003 |
| Bypasshire Limited | Information & communication | 2024 |