| Bodyzone Fitness Limited | Arts & recreation | 2020 |
| Bold Microcement Ltd | Construction | 2025 |
| Bolderwood Limited | Professional & scientific | 2012 |
| Bolderwood Solutions Limited | Information & communication | 2008 |
| Bongardia Limited | Administrative & support | 2011 |
| Bonum Construction Limited | Construction | 2007 |
| BOO! Pictures Limited | Professional & scientific | 2020 |
| Boogie Pumps (East Hampshire) Limited | Arts & recreation | 2025 |
| Booker Law Limited | Professional & scientific | 2020 |
| Bookers & Bolton Ltd | Professional & scientific | 2017 |
| Booking Solutions 360 Ltd | Administrative & support | 2025 |
| Boos Barber Alton Limited | Other services | 2025 |
| BOP Properties Limited | Real estate | 2017 |
| Boparai Investments Ltd | Real estate | 2023 |
| Botswana Tech Ltd | Financial services | 2025 |
| Boundary Close Management Limited | Professional & scientific | 2006 |
| Bourne Independent Financial Advisers Limited | Financial services | 2002 |
| Box Gardens Ltd | Agriculture & fishing | 2024 |
| Boyneswood Limited | Real estate | 2001 |
| Braai UK Catering Ltd | Hospitality | 2025 |
| Brackenbury Gardens Management Company Limited | Households | 2006 |
| Bracknell (T) Hairdressing Limited | Other services | 2000 |
| Bradford Cadrive Ltd | Administrative & support | 2024 |
| Bramc Property Ltd | Real estate | 2016 |
| Brance Limited | Information & communication | 2019 |
| Brant Storage and Removals Ltd | Transport & logistics | 2014 |
| Bray Investment Holdings Limited | Real estate | 2026 |
| Breathe Innovation Ltd | Professional & scientific | 2015 |
| Brendan Porter Bathrooms Ltd | Construction | 2025 |
| BRH Pharma Consulting Ltd | Professional & scientific | 2022 |
| Bright Space London Ltd | Construction | 2018 |
| Brighton (T) Hairdressing Limited | Other services | 2019 |
| Brighton (T2) Hairdressing Limited | Other services | 2025 |
| Brilliant Homes Limited | Real estate | 2015 |
| Bristol (T) Hairdressing Limited | Other services | 1997 |
| British Connemara Pony Society Limited | Other services | 1971 |
| British Kidney Patient Association(The) | Health & social care | 1975 |
| Britt Lloyd Limited | Professional & scientific | 2018 |
| Broadcast Digital Multimedia Solutions Limited | Other services | 2016 |
| Broadview Farm Rural Holidays Ltd | Arts & recreation | 2013 |
| Broadview Homes Limited | Construction | 2012 |
| Bromeo & Juliet Ltd | Wholesale & retail | 2016 |
| Brothers' Bakehouse Limited | Manufacturing | 2019 |
| Brough Superior Club (Spares and Events) Limited | Other services | 2005 |
| Browns of Alton Limited | Wholesale & retail | 2012 |
| Brushwork London Limited | Construction | 2023 |
| BSP Advisory Ltd | Professional & scientific | 2020 |
| BSP Events Ltd | Arts & recreation | 2024 |
| Btbb Productions SPV Limited | Information & communication | 2014 |
| Bubbles Online Services Ltd | Wholesale & retail | 2012 |
| Buckleys International Limited | Professional & scientific | 2023 |
| Build ME a Shop Limited | Information & communication | 2013 |
| Building Perspectives (Projects) Ltd | Construction | 2014 |
| Building Perspectives Limited | Professional & scientific | 2000 |
| Bumbles Farm Ltd | Real estate | 2018 |
| Bunker Diaries Limited | Administrative & support | 2022 |
| Burnham Group Limited | Financial services | 2004 |
| Burnham Management Limited | Administrative & support | 2025 |
| Bushmills Associates Limited | Professional & scientific | 2014 |
| Business@Thehive Limited | Real estate | 2024 |
| Businesses for JHB Limited | Financial services | 2013 |
| Busy Bees Nursery Alton Ltd | Education | 2006 |
| BV Holdings Ltd | Financial services | 2025 |
| BW Partners Limited | Information & communication | 2015 |
| BWM Developments Limited | Professional & scientific | 2015 |
| Byford Locum Service Ltd | Health & social care | 2022 |
| Byply Limited | Manufacturing | 2011 |
| Byrne Runciman Limited | Real estate | 2013 |
| Bytefetch Limited | Information & communication | 2005 |
| C & C Consulting Services Limited | Professional & scientific | 2016 |
| C & T Accounting Limited | Professional & scientific | 2021 |
| C R K Farm Services Ltd | Agriculture & fishing | 2025 |
| C&C Hairdressing Limited | Other services | 2019 |
| C&C Training Limited | Education | 2007 |
| C. Edwards and SON (Amusements) Limited | Arts & recreation | 1976 |
| C.Christophi Limited | Other services | 2010 |
| C.G.S. Limited | Hospitality | 1988 |
| C.J. Luff Limited | Agriculture & fishing | 2003 |
| C.J. Soft Limited | Information & communication | 1992 |
| C.Slorach Limited | Financial services | 2015 |
| C3 Plus Limited | Information & communication | 2025 |
| Cachet Events Limited | Administrative & support | 2021 |
| Cactusoft Limited | Information & communication | 1998 |
| CAD UP Ltd | Information & communication | 2010 |
| Cafe + Plus Ltd | Hospitality | 2013 |
| Cafe on the River Limited | Hospitality | 2018 |
| Caker Estates Limited | Construction | 2001 |
| Call of the Wild Productions Ltd | Arts & recreation | 2022 |
| Calver Groom Licensing Limited | Administrative & support | 2012 |
| Camberley (T) Hairdressing Limited | Other services | 2023 |
| Cambridge Education and Training UK Limited | Education | 2003 |
| Camdaw Limited | Information & communication | 1996 |
| Camden Residential Limited | Real estate | 2022 |
| Cameron Creative Design Limited | Information & communication | 2015 |
| Camoys Mead Management Limited | Water & waste | 2003 |
| Campbell Jackson Ltd | Real estate | 2021 |
| Campbell's Corner Management Limited | Households | 1998 |
| Campbell's Fish and Chips (Alton) Limited | Hospitality | 2024 |
| Canary Wharf (T) Hairdressing Limited | Other services | 1999 |
| Candor Partners Limited | Professional & scientific | 2022 |