| Bryco Construction Limited | Construction | 2023 |
| BT Benson Ltd | Professional & scientific | 2012 |
| BTB Outreach Ltd | Information & communication | 2025 |
| Bubbles Letting Limited | Real estate | 2018 |
| Bucknell Farms Limited | Agriculture & fishing | 1964 |
| Bucks Healthcare Limited | Real estate | 2013 |
| Bugs 1983 Ltd | Wholesale & retail | 2016 |
| Build Haus Limited | Construction | 2018 |
| Build My Career Limited | Wholesale & retail | 2026 |
| Builders Roots Ltd | Construction | 2025 |
| Buildverde Ltd | Professional & scientific | 2025 |
| Bulldog Rigging Services Ltd | Construction | 2021 |
| Bulldog Spirit Limited | Hospitality | 2024 |
| Bulletfish Ltd | Professional & scientific | 2019 |
| Bunch Limited | Wholesale & retail | 2017 |
| Bunn Rental Limited | Real estate | 2022 |
| Burden Bros Contractors Limited | Agriculture & fishing | 1994 |
| Burden Bros Holdings Limited | Financial services | 2010 |
| Burden Bros Investments Limited | Financial services | 2021 |
| Burden Bros Machinery Limited | Wholesale & retail | 2010 |
| Burden Property Limited | Professional & scientific | 2006 |
| Burgess Contracting Ltd | Administrative & support | 2021 |
| Burgess Property Developments Ltd | Real estate | 2025 |
| Burgess Square Management Company Limited | Real estate | 2009 |
| Burgundy Computing Limited | Information & communication | 2008 |
| Burner Boiler Services Ltd. | Construction | 2003 |
| Bursoft Ltd | Information & communication | 2013 |
| Burwell Hill Court Management Company Limited | Real estate | 2005 |
| Business Performance Solutions Europe Limited | Professional & scientific | 2003 |
| Busy Growing Limited | Professional & scientific | 2007 |
| Butlers Wharf Limited | Real estate | 2019 |
| Butterflies Healthcare Limited | Wholesale & retail | 2005 |
| Button Life Sciences Ltd | Professional & scientific | 2026 |
| Buysellix Ltd | Wholesale & retail | 2025 |
| Buzz Graphic Design Limited | Other services | 2004 |
| Buzzard Associates Limited | Education | 2014 |
| Buzzard Technology Limited | Professional & scientific | 2025 |
| Buzzard's Accountancy Limited | Professional & scientific | 2020 |
| Bviuk Ltd | Other services | 2019 |
| BVP Holdings Limited | Real estate | 2018 |
| BW Transport (Oxon) Ltd | Wholesale & retail | 2022 |
| BWB Carpet Cleaning Limited | Administrative & support | 2026 |
| BWL Rigging Services Limited | Construction | 2019 |
| BY Lounge UK Ltd | Hospitality | 2024 |
| BY Olive & Co Ltd | Professional & scientific | 2020 |
| BY Property KOC Ltd | Real estate | 2025 |
| BY SAM James Ltd | Professional & scientific | 2025 |
| BY Soren Ltd | Wholesale & retail | 2022 |
| Byhp (Tackling the Root Causes of Youth Homelessness) | Health & social care | 2006 |
| Byrne Corp Limited | Manufacturing | 2013 |
| Byte the Way Ltd | Information & communication | 2026 |
| C & M Clean With Care Ltd | Administrative & support | 2023 |
| C B Ventures Limited | Hospitality | 2014 |
| C M I Thompson Ltd | Professional & scientific | 2014 |
| C Marles Limited | Construction | 2013 |
| C S Chimneys Ltd | Construction | 2025 |
| C. H. Wortley Editorial Limited | Information & communication | 2010 |
| C. W. Booth Holdings Limited | Financial services | 1978 |
| C.G. Eddolls Transport Limited | Transport & logistics | 2002 |
| C.N. Controls Limited | Manufacturing | 1998 |
| C.N.O. Project Development & Finance Limited | Administrative & support | 2009 |
| C3G Consulting Limited | Professional & scientific | 2019 |
| C3T Investments Ltd | Professional & scientific | 2012 |
| C3T Solutions LLP | | 2016 |
| Cadence Acoustics Ltd | Professional & scientific | 2026 |
| Cadence PT Limited | Professional & scientific | 2024 |
| Caerus Corporate Finance Ltd | Extraterritorial | 2013 |
| Caesoose Studios Limited | Information & communication | 2025 |
| Cafer Ltd | Wholesale & retail | 2021 |
| Caine Properties Ltd | Real estate | 2024 |
| CAL Demicoli Media Limited | Information & communication | 2022 |
| CAL Engineering Ltd | Professional & scientific | 2024 |
| Callisto WAX Company Limited | Wholesale & retail | 2021 |
| Caltec Engineering Limited | Professional & scientific | 2018 |
| Caltrop Games Ltd | Manufacturing | 2022 |
| Camden Commercial Property Limited | Real estate | 2005 |
| Camden Holdings Limited | Financial services | 2020 |
| Camden Motor Group Limited | Professional & scientific | 2003 |
| Camden Motors (Holdings) Limited | Real estate | 1996 |
| Camden Motors Limited | Professional & scientific | 1936 |
| Camden Property Development Limited | Construction | 2013 |
| Camden Ventures Limited | Real estate | 2020 |
| Cameo Consultancy (Recruitment) Limited | Administrative & support | 2012 |
| Cameron Court Limited | Real estate | 1990 |
| Cameron Trinity Limited | Financial services | 1996 |
| Campanello Property Ltd | Real estate | 2019 |
| Campbell Martinez LLP | | 2022 |
| Campion (Rural) Limited | Real estate | 2012 |
| Can'T Find a Better Name Limited | Professional & scientific | 2015 |
| Canada Close Limited | Real estate | 1998 |
| Canal House Management Limited | Households | 2003 |
| Candle Foot Films Ltd | Professional & scientific | 2021 |
| Candy Central Ltd | Wholesale & retail | 2025 |
| Caninecards Ltd | Wholesale & retail | 2025 |
| Canned Vision Limited | Information & communication | 2024 |
| Cannonphotography Ltd | Professional & scientific | 2025 |
| Canons Ashby Limited | Households | 2014 |
| CAP & Co Nutra Ltd | Manufacturing | 2024 |
| Capital Facilities Management Limited | Professional & scientific | 1995 |
| Capital Gain Holdings Limited | Financial services | 2018 |