| Buddy Brands Limited | Wholesale & retail | 2009 |
| Buddy Dog Ltd | Health & social care | 2025 |
| Burcote Integrated Business Solutions Limited | Administrative & support | 2004 |
| Burgo UK Limited | Manufacturing | 1990 |
| Business Funding Solutions Limited | Financial services | 2023 |
| Buybridge Limited | Professional & scientific | 2009 |
| C & L Newport Pagnell Ltd | Construction | 2015 |
| C & L Roofline Ltd | Construction | 2015 |
| C & S Carpentry Corporation Limited | Construction | 2001 |
| C Browne Consulting Limited | Information & communication | 2019 |
| C J Richards Electrical Limited | Extraterritorial | 2005 |
| C&S Installations Ltd | Construction | 2026 |
| C.H.Smith and Sons Limited | Real estate | 1953 |
| C.J. Haynes & SON Limited | Transport & logistics | 1984 |
| Cable Run Services Limited | Construction | 2022 |
| Cablelynx Limited | Manufacturing | 2002 |
| CAG Consultancy Ltd | Professional & scientific | 2023 |
| Cake Secret Limited | Manufacturing | 2022 |
| Caldecote Court Management Limited | Administrative & support | 2007 |
| Calidos Bakery Ltd | Manufacturing | 2018 |
| Caljam Limited | Administrative & support | 2010 |
| Cambourne Travel Limited | Administrative & support | 1973 |
| Camden Square Management Limited | Households | 2025 |
| Camox Building Services Limited | Construction | 1974 |
| Capel Training Limited | Education | 2022 |
| Capel's Cabinet Making Limited | Manufacturing | 2005 |
| Car-Search.Ai Limited | Information & communication | 2025 |
| Carabassi Holdings Limited | Financial services | 2022 |
| Carbee Limited | Wholesale & retail | 2025 |
| Card Halo Ltd | Wholesale & retail | 2025 |
| Career Synergy Limited | Education | 2009 |
| Carradine Group Limited | Professional & scientific | 2017 |
| Carrington Hair Ltd | Other services | 2021 |
| Carus Advisory Services Ltd | Professional & scientific | 2020 |
| Cavendish Road Management Company Limited | Households | 1998 |
| CBW UK Solutions Limited | Administrative & support | 2014 |
| Ceylon Cinnamon Limited | Hospitality | 2008 |
| CFC Cladding Flooring Ceilings Limited | Professional & scientific | 2007 |
| CH. Kapnos&Son Trading Ltd | Wholesale & retail | 2020 |
| Chad Advisory Ltd | Administrative & support | 2016 |
| Chapman Building Services Limited | Construction | 2023 |
| Chapman HR Consulting Limited | Administrative & support | 2012 |
| Chapmans Building Services Ltd | Construction | 2018 |
| Char, Mole and FOX Limited | Real estate | 2020 |
| Charcoal Grill Kebabs Ltd | Hospitality | 2014 |
| Chargrilled Clothing Ltd | Wholesale & retail | 2015 |
| Chase Group Holdings Limited | Financial services | 2025 |
| Chase UK Group Ltd | Construction | 2024 |
| Chasm Holdings Limited | Financial services | 2024 |
| Chasm Ltd | Professional & scientific | 2017 |
| Cheeky Chops Catering Ltd | Hospitality | 2026 |
| Chef HAT Home Weddings and Events Ltd | Hospitality | 2025 |
| Cherry Education Consultancy Ltd | Other services | 2012 |
| Chicheley Developments Ltd | Wholesale & retail | 2016 |
| Chicheley Farms Limited | Agriculture & fishing | 1987 |
| Childbase Employee Ownership Trustee Limited | Administrative & support | 2017 |
| Childbase Partnership Limited | Education | 1989 |
| Chilli Accounting Ltd | Professional & scientific | 2015 |
| Chiltern Gate Management Limited | Households | 2025 |
| Chinnery Hotels Limited | Hospitality | 2019 |
| Chrisbeth Ltd | Real estate | 2024 |
| Christine Franke Limited | Health & social care | 2002 |
| City Hypnosis UK Limited | Health & social care | 2007 |
| Cityapt Ltd | Hospitality | 2019 |
| Cjls Properties Ltd | Real estate | 2022 |
| Clark Pritchard LLP | | 2012 |
| Clarkson Construction Ltd | Construction | 2025 |
| Claudia Valentin Ltd | Wholesale & retail | 2014 |
| Clay PIT Close Management Ltd | Households | 2025 |
| Clean CUT Drilling Ltd | Construction | 2017 |
| Clean CUT Fire Protection Ltd | Construction | 2024 |
| Clean Wata Ltd. | Other services | 2020 |
| Cleanslate (Wokingham) Ltd | Construction | 2019 |
| Clear River Therapy Services Ltd | Education | 2022 |
| CLEARANCE24 Ltd | Wholesale & retail | 2024 |
| Clem Hill Ltd | Information & communication | 2025 |
| Clifton Rees Consulting Limited | Professional & scientific | 2025 |
| CLM Fleet Management Ltd | Wholesale & retail | 2010 |
| Clocking in Machines Limited | Wholesale & retail | 1992 |
| Cloudcart Retail Ltd | Wholesale & retail | 2025 |
| Cloudco (UK) Ltd | Professional & scientific | 1994 |
| CMC 1107A Limited | Professional & scientific | 2007 |
| CMC BRY Limited | Real estate | 2008 |
| CMC OM Limited | Real estate | 2008 |
| CMP Consultancy Limited | Administrative & support | 2019 |
| Coda Solutions Ltd | Manufacturing | 2013 |
| Coffee Crowd Ltd | Hospitality | 2025 |
| Coffee Primo Burger King Limited | Professional & scientific | 2009 |
| Colam Ltd | Construction | 2022 |
| Colarusso & SON Limited | Wholesale & retail | 2024 |
| Collab Works Limited | Information & communication | 2026 |
| Collectifi Ltd | Information & communication | 2014 |
| Colne Valley Motorway Service Area Limited | Construction | 2019 |
| Colonial Build Ltd | Construction | 2011 |
| Comet Consultants Ltd | Professional & scientific | 2025 |
| Comkat Limited | Information & communication | 2011 |
| Community Medical Solutions Limited | Health & social care | 2011 |
| Completely Eco Limited | Construction | 2022 |
| Completely Wired Limited | Construction | 2006 |
| Compliance Delivered Limited | Professional & scientific | 2026 |