| Cadmus Management Company Limited | Households | 2020 |
| Cadrecruit Ltd | Extraterritorial | 2002 |
| Cafe Destino Limited | Hospitality | 2006 |
| Caitenix Ltd | Information & communication | 2025 |
| Cakes by Maze Ltd | Wholesale & retail | 2023 |
| Cakes Elite Ltd | Wholesale & retail | 2020 |
| Calc Co Ltd | Information & communication | 2006 |
| Caldicott Hamilton Limited | Professional & scientific | 2001 |
| Calibre Candidates Ltd | Administrative & support | 2019 |
| Calico Private Travel Limited | Administrative & support | 2024 |
| Calida Care Ltd | Health & social care | 2019 |
| Calleva Homes Ltd | Construction | 2021 |
| Calloc Systems Limited | Information & communication | 2022 |
| Calo Solutions Ltd | Transport & logistics | 2017 |
| Calverton Group Limited | Financial services | 1997 |
| Cameron RSC Ltd | Health & social care | 2023 |
| Camvale Property LLP | | 2019 |
| CAN Business Support Limited | Wholesale & retail | 2020 |
| Candid Consultants Ltd | Information & communication | 2016 |
| Candid Property Services Ltd | Real estate | 2020 |
| Candle Family Creations Ltd | Manufacturing | 2024 |
| Candover Green (Saint Cross) Limited | Real estate | 2017 |
| Candover Green Developments Limited | Real estate | 2015 |
| Candover Green Limited | Administrative & support | 2008 |
| Cangs Property Group Ltd | Real estate | 2026 |
| Canine Arthritis Centre Ltd | Professional & scientific | 2023 |
| Canine Controlled Chaos Ltd | Wholesale & retail | 2025 |
| Cannock Court Management Company Limited | Households | 2003 |
| Cantel (UK) Limited | Wholesale & retail | 2005 |
| Cantel Medical (UK) Limited | Financial services | 1992 |
| Canterfield Risk Management Ltd | Administrative & support | 2023 |
| Capercaillie Consulting Ltd | Information & communication | 2023 |
| Capital Consignments Ltd | Information & communication | 2018 |
| Capital Crown Wills Ltd | Professional & scientific | 2014 |
| Capital Drainage Ltd | Administrative & support | 2010 |
| Capital Handling Ltd | Transport & logistics | 2007 |
| Capital Mortgage Protection Ltd | Financial services | 2023 |
| Capital Wills Limited | Professional & scientific | 1997 |
| Capoeira Flow Limited | Arts & recreation | 2012 |
| Capricorn Applied Technology Ltd | Manufacturing | 2026 |
| Capricorn Automotive Limited | Manufacturing | 1992 |
| Car Masters BSK Ltd | Wholesale & retail | 2025 |
| Car Trim Limited | Other services | 2017 |
| Carat Cleaning Services Ltd. | Administrative & support | 2015 |
| Carbon Footprint Limited | Professional & scientific | 2002 |
| CARBON13 Multimedia Ltd | Wholesale & retail | 2009 |
| CARBON8LIGHTING Ltd | Manufacturing | 2024 |
| Carbonica Licensing Limited | Information & communication | 2025 |
| Carbonica Ltd | Administrative & support | 2024 |
| Card Terminal Services Ltd | Information & communication | 2010 |
| Care & Integrity Ltd | Health & social care | 2017 |
| Care Concept Services Ltd | Administrative & support | 2025 |
| Care Force Nest Limited | Real estate | 2022 |
| Care Force Staffing Ltd | Health & social care | 2015 |
| Care Force Wellness Ltd | Arts & recreation | 2022 |
| Care Opportunities Ltd | Health & social care | 2004 |
| Careguard Security Limited | Administrative & support | 1989 |
| Caribbean Great Essentials Ltd | Wholesale & retail | 2025 |
| Caring Families CIC | Health & social care | 2025 |
| Carisbrooke Dental Leicester Limited | Health & social care | 2016 |
| Carisbrooke Holdings Limited | Financial services | 2016 |
| Carleton Management Company Limited | Households | 1998 |
| Carol Boland Ltd | Professional & scientific | 2019 |
| Cars Care Specialist Ltd | Other services | 2024 |
| Carson & Hughes Ltd | Financial services | 2018 |
| Carter Sales Consultancy Ltd | Professional & scientific | 2026 |
| Carthage Renaissance Ltd | Real estate | 2023 |
| Carwens Ltd | Information & communication | 2023 |
| CAS Organisation Ltd | Wholesale & retail | 2017 |
| Casa Capital Investments Limited | Financial services | 2019 |
| Casadetony Ltd | Real estate | 2025 |
| Casey.O Ltd | Other services | 2021 |
| Caslab Limited | Health & social care | 2008 |
| Cass TEM UK Limited | Information & communication | 2017 |
| Cassandra Goring Consultancy Ltd | Administrative & support | 2024 |
| Cassie Valenti Skin and Aesthetics Academy Limited | Education | 2026 |
| Cassini Group Limited | Professional & scientific | 2016 |
| Castalia Consulting Limited | Professional & scientific | 2018 |
| Castle House Medical Limited | Health & social care | 2017 |
| Castle Lift Trucks Limited | Extraterritorial | 1987 |
| Castle Park Limited | Health & social care | 2008 |
| Castleguard Limited | Professional & scientific | 1993 |
| Castleprime Construction Limited | Construction | 2017 |
| Casual Ballerz CIC | Other services | 2017 |
| Cat Fire Ltd | Construction | 2013 |
| Catalonia Consulting Limited | Wholesale & retail | 2014 |
| Catalyst Space Limited | Other services | 2019 |
| Caterplan Solutions Ltd | Administrative & support | 2009 |
| Catholic Gym Society CIC | Other services | 2025 |
| Catlin Plumbing & Heating Ltd | Construction | 2001 |
| Cattax Limited | Professional & scientific | 2025 |
| Cavalry Claims Solutions Ltd | Professional & scientific | 2024 |
| CB Management Consultancy Limited | Information & communication | 2014 |
| Ccay Investments Limited | Real estate | 2025 |
| CCS Mobile (SE) Ltd | Information & communication | 2007 |
| CCU Estates Ltd | Real estate | 2025 |
| CCU Proflo Limited | Professional & scientific | 2012 |
| Cculture Vvalley Ltd | Arts & recreation | 2025 |
| CD Hairstylist Ltd | Other services | 2024 |
| CD Painting& Decorating Limited | Construction | 2023 |