| C & T Health Ltd | Health & social care | 2022 |
| C Adama Ltd | Professional & scientific | 2022 |
| C and J Property Developments Limited | Construction | 2014 |
| C G R Plumbing Limited | Construction | 2015 |
| C Gilmartin Ltd | Real estate | 2021 |
| C H Management Limited | Real estate | 1996 |
| C L Photography Ltd | Professional & scientific | 2024 |
| C Rees 4 Flooring Limited | Construction | 2021 |
| C Waites Limited | Health & social care | 2024 |
| C Webb Contracting Ltd | Construction | 2023 |
| C&A Civils Ltd | Construction | 2022 |
| C&C Grab Hire Ltd | Water & waste | 2022 |
| C&I Specs Limited | Wholesale & retail | 2024 |
| C&M Capital Group Ltd | Financial services | 2025 |
| C&M ENG Ltd | Transport & logistics | 2023 |
| C&M Health Limited | Health & social care | 2004 |
| C&O Smart Way Ltd | Transport & logistics | 2025 |
| C&P General Construction Ltd | Construction | 2021 |
| C&R Consulting Ltd | Construction | 2026 |
| C&R KPO Services Limited | Professional & scientific | 2020 |
| C&S Traffic Management Ltd | Public administration | 2026 |
| C&T Property Developments Ltd | Real estate | 2023 |
| C-Ong Aesthetic Ltd | Wholesale & retail | 2021 |
| C-Sics Ltd | Manufacturing | 2023 |
| C-View Limited | Other services | 1994 |
| C.H. & M. Gregory & Partners Limited | Real estate | 1977 |
| C.H.S. Property Investments Limited | Real estate | 2004 |
| C.J. Homes Limited | Construction | 1997 |
| C.Roper Electrical Limited | Construction | 2003 |
| C.S.M. Jewellery Service Ltd | Manufacturing | 2025 |
| C.W.A.B. Ltd | Information & communication | 2016 |
| C4 Creative Ltd | Manufacturing | 2026 |
| Caam Properties Ltd | Real estate | 2025 |
| Caava Ltd | Professional & scientific | 2025 |
| CAB Locums Ltd | Professional & scientific | 2016 |
| Cabbytax Limited | Professional & scientific | 2025 |
| Cabin Marsh Ltd | Real estate | 2020 |
| Cable Engagement Limited | Information & communication | 2006 |
| Cabletech Solutions Limited | Construction | 2024 |
| Caburn Group Limited | Financial services | 2020 |
| Caburn Telecom Limited | Information & communication | 2020 |
| Cache Property Group Limited | Real estate | 2021 |
| Caddington Golf Course Construction Ltd | Extraterritorial | 2025 |
| Cadogan Court (BOW) Limited | Households | 2005 |
| CADR-3 Limited | Hospitality | 2024 |
| Cafe Cidade Limited | Wholesale & retail | 2022 |
| Cafe Deli Travel Limited | Real estate | 2025 |
| Caffee Beldj Limited | Hospitality | 2022 |
| Cafkam Limited | Hospitality | 2022 |
| Café Hampstead Limited | Hospitality | 2017 |
| Cagefit Gyms Ltd | Arts & recreation | 2019 |
| Cagefit Watford Ltd | Health & social care | 2024 |
| Cairnbrook Avenue Limited | Real estate | 2025 |
| Caissa IT Consulting Ltd | Information & communication | 2013 |
| Caked by KIM Limited | Manufacturing | 2024 |
| Calabria Creative Limited | Professional & scientific | 2016 |
| Calauz Services Ltd | Administrative & support | 2021 |
| Calcutta Cravings Ltd | Hospitality | 2025 |
| Calenza Studio Ltd | Wholesale & retail | 2025 |
| Cali Construction & Landscape Ltd | Construction | 2023 |
| Calibre Healthcare Ltd | Health & social care | 2016 |
| Calin MGS Ltd | Construction | 2020 |
| Calin’S Carpet Cleaners Ltd | Manufacturing | 2023 |
| Callaghan Consultant Services Limited | Professional & scientific | 2006 |
| Callaghan Project Services Limited | Construction | 2024 |
| Callandor Ltd | Information & communication | 2011 |
| Callaway Studio Ltd | Arts & recreation | 2026 |
| Callwithme Ltd. | Wholesale & retail | 2006 |
| Calorie Consulting Limited | Professional & scientific | 1997 |
| Calvin Racing & Betting Limited | Arts & recreation | 2016 |
| Cambec Limited | Information & communication | 2012 |
| Cambro Contractors Limited | Extraterritorial | 1965 |
| Camcyan Ltd | Information & communication | 2020 |
| Camden Court Aylesbury Management Company Limited(The) | Households | 1979 |
| Camelot UK Lotteries Limited | Arts & recreation | 1993 |
| Cameron Darroch Associates Limited | Professional & scientific | 2000 |
| Cameron James Construction Services Ltd | Construction | 2008 |
| Cameron James Recruitment Ltd | Administrative & support | 2007 |
| Campbell Strauss Ltd | Professional & scientific | 2011 |
| Camroc Services Ltd | Construction | 2024 |
| Camsco Ltd | Information & communication | 2014 |
| Camsons Property Services Ltd | Professional & scientific | 2022 |
| Canagan 2021 Limited | Financial services | 2021 |
| Canagan Group Limited | Financial services | 2021 |
| Candid Healthsystems Consultants Limited | Professional & scientific | 2022 |
| Candid Resourcing Partners Limited | Administrative & support | 2024 |
| Canfield 149 Ltd | Extraterritorial | 2020 |
| Canine & Feline Behaviour Association | Education | 2008 |
| Canopi Horizon Limited | Information & communication | 2025 |
| Cantillon Holdings Limited | Administrative & support | 2004 |
| Cantor Developments Limited | Real estate | 1997 |
| CAP Certified Ltd | Information & communication | 2019 |
| Cape London Limited | Wholesale & retail | 2024 |
| Capel Carpets & SON Limited | Wholesale & retail | 2007 |
| Capel Gardens (Pinner) Residents Limited | Households | 1971 |
| Capelli (Radlett) Limited | Other services | 2012 |
| Capextra Technology Solutions Ltd | Information & communication | 2015 |
| Capital Asset Holdings Limited | Information & communication | 2020 |
| Capital Auto Services Ltd | Wholesale & retail | 2025 |
| Capital Blue Partners UK Limited | Real estate | 2023 |