| Bull Services Limited | Construction | 2017 |
| Bungaja Ltd | Administrative & support | 2024 |
| Bunks Limited | Manufacturing | 2015 |
| Buongiorno Italia Limited | Wholesale & retail | 2023 |
| Bure Meadows (Aylsham) Management Company Limited | Households | 2015 |
| Burger Crafter Limited | Hospitality | 2025 |
| Burgitzza Hemel Ltd | Professional & scientific | 2020 |
| Burlington Rise Management Company Limited | Households | 2023 |
| Burnside Resource Management Limited | Administrative & support | 2017 |
| Bury Court Hemel Hempstead Freehold Ltd | Households | 2021 |
| Bury Court Management Company Limited | Households | 1988 |
| Bushey Wood Road Management Company Limited | Households | 2011 |
| Bushwood Antiques Limited | Wholesale & retail | 1997 |
| Business Film Booth Limited | Information & communication | 2015 |
| BUSINESS360 Limited | Financial services | 2005 |
| Busy Brains Schools Ltd | Education | 2023 |
| Busy Brains Tuition Ltd | Education | 2019 |
| Butlins Development Limited | Construction | 2011 |
| Butlins Limited | Real estate | 2005 |
| Butlins Operations Limited | Hospitality | 2012 |
| Butlins Property (Hotel) Limited | Real estate | 2012 |
| Butlins Skyline Limited | Hospitality | 2000 |
| Buttercup Care Limited | Health & social care | 2015 |
| Butterfly Mill (Horsford) Management Company Limited | Households | 2015 |
| Buttons Recruitment Ltd | Administrative & support | 2024 |
| Buxton Investments Limited | Real estate | 2007 |
| Buzz Inc Ltd | Administrative & support | 2025 |
| Bvf-Flr Ltd | Construction | 2025 |
| BVU Media Ltd | Administrative & support | 2023 |
| BVU Ventures Ltd | Professional & scientific | 2020 |
| Bwindi Handmade Crafts CIC | Wholesale & retail | 2025 |
| Bwok Limited | Wholesale & retail | 2024 |
| BWS Security Limited | Administrative & support | 2015 |
| BY Aliss Limited | Wholesale & retail | 2025 |
| BY Your Side Limited | Health & social care | 2015 |
| Bymayaa Ltd | Wholesale & retail | 2025 |
| Byrons Wood (Hucknall) Management Company Limited | Households | 2014 |
| Bytebrothers Consulting Ltd | Information & communication | 2025 |
| Bywater Catering Ltd | Hospitality | 2026 |
| Bywater Chef Ltd | Hospitality | 2026 |
| Bywater Culinary Limited | Hospitality | 2026 |
| BZX Property Limited | Real estate | 2017 |
| C & R Outdoor Lighting Limited | Manufacturing | 1991 |
| C & S Investment Options Ltd | Financial services | 2010 |
| C and I Control Systems Limited | Manufacturing | 2010 |
| C Anderson Electrical Services Limited | Construction | 2008 |
| C B & L Pubs Ltd | Hospitality | 2025 |
| C D Moorcroft Electrical Services Ltd | Construction | 2017 |
| C F Wholesale Ltd | Construction | 2021 |
| C J Lacson Ltd | Health & social care | 2021 |
| C M Grounds Property Maintenance Ltd | Administrative & support | 2025 |
| C O B Building Services Ltd | Construction | 2011 |
| C W Services Ltd | Construction | 2024 |
| C White Flooring Ltd | Construction | 2026 |
| C&L Investments Limited | Real estate | 2016 |
| C&L Rigging Ltd | Construction | 2021 |
| C&M Electronics Limited | Information & communication | 2018 |
| C&O Scenic Ltd | Information & communication | 2019 |
| C&Of Consulting Ltd | Professional & scientific | 2025 |
| C&P Creative Construction Ltd | Construction | 2024 |
| C-Repairs Limited | Information & communication | 2012 |
| C.P. Installations Ltd | Construction | 2025 |
| C4F CIC | Health & social care | 2019 |
| CA Property Investments Ltd | Extraterritorial | 2015 |
| CAB Inns Limited | Hospitality | 2018 |
| Caballero Construction Limited | Construction | 2025 |
| Caboodle Store Ltd | Transport & logistics | 2018 |
| Cadcorp Limited | Information & communication | 1985 |
| Cadcreate Ltd | Professional & scientific | 2020 |
| Cadi Software Ltd | Information & communication | 2026 |
| CAE Assets Limited | Extraterritorial | 2005 |
| CAE Capel Management Company Limited | Households | 2020 |
| CAE Technology Holdings Limited | Financial services | 2010 |
| CAE Technology Services Limited | Information & communication | 1992 |
| Caerus Assets Limited | Financial services | 2018 |
| Cafe CAN Limited | Hospitality | 2013 |
| Cafe SOL Limited | Hospitality | 2011 |
| CAG Accounting Services Ltd | Professional & scientific | 2018 |
| CAH Painting & Decorating Ltd | Construction | 2020 |
| CAI Education & Skills Limited | Education | 2007 |
| Cake and Bake Limited | Manufacturing | 2021 |
| Calbio Ltd | Professional & scientific | 2014 |
| Calder Search Ltd | Administrative & support | 2025 |
| Caldrail Limited | Administrative & support | 1976 |
| Caliam Consulting Limited | Professional & scientific | 2003 |
| Calibre Strategies Limited | Professional & scientific | 2008 |
| California Bidco Limited | Financial services | 2018 |
| California Midco Limited | Financial services | 2018 |
| California Topco Limited | Financial services | 2018 |
| Calliper Innovations Limited | Extraterritorial | 2012 |
| Calliper Investments Ltd | Financial services | 2024 |
| Callum James Consulting Ltd | Administrative & support | 2009 |
| Calverton Products P.L.C. | Professional & scientific | 1954 |
| Calypso Vibes Ltd | Hospitality | 2026 |
| CAM Designer Flooring Ltd | Construction | 2024 |
| Camainet Consultants Limited | Information & communication | 2010 |
| Camanchi Bungay Ltd | Financial services | 2021 |
| Camanchi Care Limited | Health & social care | 2018 |
| Campbell Grab Services Ltd | Water & waste | 2012 |
| Camperite Leisure Limited | Wholesale & retail | 2004 |