| Campion (Marden) Management Company Limited | Households | 2016 |
| Campkin Mechanical Installations Ltd | Construction | 2022 |
| Campsites Website Limited | Arts & recreation | 2024 |
| Canal Village (Ellesmere Port) Management Company Limited | Households | 2006 |
| Canalside Estates Ltd | Households | 2014 |
| Candl Recruitment Ltd | Administrative & support | 2025 |
| Candy Floss and Dreams Ltd | Wholesale & retail | 2020 |
| Canko Construction Limited | Construction | 2023 |
| Canoe Sports Trust C.I.C. | Arts & recreation | 1996 |
| Canon Court Wallington Management Limited | Households | 2010 |
| Capeguide Limited | Administrative & support | 2005 |
| Capitar Limited | Professional & scientific | 2021 |
| Cappadocia Moments Ltd | Hospitality | 2023 |
| Cappuccio Italian Delicatessen Limited | Hospitality | 2015 |
| Capricon Homes Limited | Construction | 2016 |
| Captured Art & Design Ltd | Administrative & support | 2018 |
| Car Doctor Hemel Hempstead Ltd | Wholesale & retail | 2013 |
| Car Mech Services Ltd | Wholesale & retail | 2024 |
| Car Point Ltd | Wholesale & retail | 2017 |
| Car Repair Services Limited | Wholesale & retail | 2006 |
| Car Zoon Ltd | Wholesale & retail | 2025 |
| Cardbay Ltd | Wholesale & retail | 2025 |
| Cardeasy Limited | Extraterritorial | 1999 |
| Cardiax SLE Ltd | Professional & scientific | 2025 |
| Cardinal Torch Company UK Ltd | Wholesale & retail | 2023 |
| Cardington Joinery Ltd | Real estate | 2021 |
| Cards Direct Retail Limited | Wholesale & retail | 2012 |
| Care by LAH Ltd | Health & social care | 2025 |
| Care Cascades Ltd | Information & communication | 2023 |
| Care Co Plus Ltd | Real estate | 2019 |
| Care Guider Limited | Information & communication | 2023 |
| Care Support Empower Ltd | Health & social care | 2021 |
| Careline Moving & Storage UK Limited | Transport & logistics | 2013 |
| Carell Limited | Health & social care | 2012 |
| Caremind Homecare and Nursing Ltd | Health & social care | 2013 |
| Carl Ellis Heating & Plumbing Ltd | Construction | 2019 |
| Carl P Limited | Wholesale & retail | 2023 |
| Carline Motors Limited | Wholesale & retail | 2019 |
| Carltimo Logistics Ltd | Transport & logistics | 2014 |
| Carnival Place Residents Management Company Limited | Households | 2025 |
| Carnivool Events & Productions Ltd | Other services | 2022 |
| Caroline Hudd Ltd | Administrative & support | 2025 |
| Carpenters Wharf Management Company Limited | Real estate | 2016 |
| Carpentry A&D Ltd | Manufacturing | 2025 |
| Carphatian Ltd | Wholesale & retail | 2019 |
| Carr Richards Solicitors Limited | Professional & scientific | 2013 |
| Carr Stocktakers Limited | Administrative & support | 1999 |
| Carrera Property Services Limited | Construction | 2012 |
| Carrob Controls and Services Limited | Professional & scientific | 1988 |
| Cars GT Limited | Information & communication | 2018 |
| Cars Hub (UK) Ltd | Wholesale & retail | 2020 |
| CARSAMBA55 Limited | Hospitality | 2023 |
| Carshalton Lodge Residents (Oatlands) Limited | Households | 1986 |
| Carson Windows and Doors Limited | Construction | 2019 |
| Carter Fleet Ltd | Professional & scientific | 2025 |
| Carters Caversham Management Company Reading Limited | Households | 2024 |
| CAS Logistic Ltd | Transport & logistics | 2016 |
| Casa Cannoli Enterprise Ltd | Wholesale & retail | 2024 |
| Casa Creation Limited | Real estate | 2025 |
| Casa DE BO Ltd | Manufacturing | 2025 |
| Cascade Canyon Limited | Other services | 2024 |
| Cascade Social Enterprise Ltd | Education | 2020 |
| Case Fleet Limited | Transport & logistics | 2018 |
| Casmon Investments Limited | Financial services | 2026 |
| Casper Kebab Ltd | Hospitality | 2024 |
| Cassiobury Wellness Ltd | Wholesale & retail | 2024 |
| Castello Holding Company Limited | Professional & scientific | 2014 |
| Castillo UNO Limited | Professional & scientific | 2025 |
| Castle Bishop Limited | Hospitality | 2019 |
| Castle Care Products Ltd. | Extraterritorial | 2011 |
| Castle Property Maintenance Limited | Administrative & support | 2010 |
| Castle Quay Management Limited | Households | 2006 |
| Castle Syke & Sandy Gate (Pontefract) Management Company Limited | Households | 2025 |
| Castlefields (Coinsborough) Management Company Limited | Households | 2003 |
| Castles Boxmoor LLP | | 2010 |
| Castles Property Group Ltd | Financial services | 2024 |
| Castles Property Lettings Limited | Real estate | 2008 |
| Castles Property Sales (Eaton Bray) Limited | Real estate | 2010 |
| Castles Property Sales (Kings Langley) Ltd | Real estate | 2014 |
| Castles Property Sales FS Ltd | Financial services | 2024 |
| Castles Property Sales Limited | Real estate | 2018 |
| Castlestone Specialist Property Finance Ltd | Financial services | 2024 |
| Catalyst 75 Ltd | Construction | 2017 |
| Catalyst Developments Limited | Real estate | 2022 |
| Cater 14 Limited | Hospitality | 2021 |
| Catherine's Angels Ltd | Administrative & support | 2025 |
| Cathpro Consult Limited | Professional & scientific | 2010 |
| Cavanik Limited | Wholesale & retail | 2019 |
| Cavehurst Limited | Financial services | 1995 |
| Cayhill Partners Limited | Administrative & support | 2014 |
| CBS Showrooms Limited | Wholesale & retail | 2008 |
| CC Building Solutions Limited | Construction | 2018 |
| CCA Developments Ltd | Construction | 2020 |
| CCA Telecom Ltd | Construction | 2023 |
| CCR Autos Ltd | Wholesale & retail | 2025 |
| CCR Properties (Boxmoor) Ltd | Real estate | 2022 |
| Cctv & Jetting Ltd | Construction | 2026 |
| CD Cheltenham Holdco Ltd | Financial services | 2022 |
| CD Contracting Limited | Construction | 2018 |
| CD Welcombe Holdco Limited | Financial services | 2021 |