| Calcoop Investments Limited | Real estate | 2024 |
| Calderbeck Ltd | Households | 1999 |
| Caldicot Scaffolding Limited | Construction | 2023 |
| Caledonian Wind Limited | Financial services | 2010 |
| Call Bruce Limited | Administrative & support | 2014 |
| CALL2CONVERT Ltd | Professional & scientific | 2025 |
| Calloutcrewuk Ltd | Construction | 2025 |
| Callscape Limited | Professional & scientific | 2022 |
| Calm Capital Investment Limited | Financial services | 2026 |
| Calm Capital Limited | Hospitality | 2024 |
| Calmcare Consulting Limited | Professional & scientific | 1993 |
| Calnia Catering Ltd | Hospitality | 2020 |
| Caman Investments | Professional & scientific | 2016 |
| Cambria Legal Ltd | Professional & scientific | 2019 |
| Cambrian Capital Limited | Real estate | 2019 |
| Cambridge RD Ltd | Hospitality | 2020 |
| Camden Court (Ryde) Management Co Limited | Households | 2001 |
| Camden Design Ltd | Information & communication | 2009 |
| Camelot Electrical Limited | Construction | 2000 |
| Camelot Films Limited | Information & communication | 2013 |
| Camelot Holding Group Limited | Financial services | 2024 |
| Camelot Property Services Limited | Real estate | 2024 |
| Camelot Security Limited | Administrative & support | 2009 |
| Camora Transport Ltd | Transport & logistics | 2025 |
| Campbell Estates SW Ltd | Professional & scientific | 2016 |
| Camphill Community Sports Club CIC | Arts & recreation | 2016 |
| Camrose Barns Management Ltd | Real estate | 2022 |
| CAN Freight Ltd | Transport & logistics | 2011 |
| Canal Cottage Shropshire Ltd | Other services | 2026 |
| Candwr Investments Limited | Real estate | 2016 |
| Candwr Property Group Ltd | Real estate | 2025 |
| Canford Paddock (Poole) Management Co Limited | Households | 2019 |
| Canham Williams Estates Ltd | Real estate | 2019 |
| Canpolat Property Ltd | Real estate | 2020 |
| Cant&White Limited | Hospitality | 2018 |
| Canvas Home Staging Ltd | Administrative & support | 2023 |
| CAP Capital Investments Ltd | Wholesale & retail | 2022 |
| Capability Heath Limited | Manufacturing | 2023 |
| Capello (by KMM) Ltd | Other services | 2022 |
| Capisce Ltd | Professional & scientific | 2017 |
| Capital Building Systems Ltd | Construction | 2013 |
| Capital Cladding Services Limited | Manufacturing | 2023 |
| Capital Cladding Systems Limited | Manufacturing | 2023 |
| Capital Coated Steel Limited | Manufacturing | 1972 |
| Capital Couriers 4 YOU Limited | Transport & logistics | 2025 |
| Capital Grid Systems Limited | Manufacturing | 2023 |
| Capital Servicess Ltd | Administrative & support | 2023 |
| Capital Topco Limited | Financial services | 2019 |
| Capital Trading (Holdings) Limited | Manufacturing | 1991 |
| Capital Windscreens & Body Glass & Conversions Ltd | Wholesale & retail | 2025 |
| Capitol Taxis Limited | Transport & logistics | 2013 |
| Capoeira Casnewydd C.I.C. | Education | 2023 |
| Caprio Ltd | Hospitality | 2025 |
| Capten Consulting Ltd | Professional & scientific | 2021 |
| Car Clinic (Brynmenyn) Ltd | Wholesale & retail | 2013 |
| Car Integration Ltd | Wholesale & retail | 2020 |
| Car MGT Ltd | Construction | 2023 |
| Car Plus Motors UK Ltd | Wholesale & retail | 2022 |
| CAR4YOU Cardiff Ltd | Wholesale & retail | 2017 |
| Caradog Promotions Ltd | Arts & recreation | 2017 |
| Caramella Stays Limited | Real estate | 2023 |
| Caravan and Motorhome Training Ltd | Education | 2020 |
| Carbon 6IX Ltd | Manufacturing | 2013 |
| Carbon Fiit Limited | Arts & recreation | 2019 |
| Carbon Financial Planning Limited | Other services | 2011 |
| Carbon Recovery Operations Limited | Professional & scientific | 2024 |
| Carbonmakers Limited | Manufacturing | 2019 |
| Carbootuk Ltd | Professional & scientific | 2025 |
| Carc Consultancy Ltd | Administrative & support | 2023 |
| Cardiac Imaging Limited | Administrative & support | 2024 |
| Cardiff Academy of Fencing CYF | Education | 2019 |
| Cardiff Angling Centre Limited | Wholesale & retail | 2014 |
| Cardiff Basketball Foundation CIC | Other services | 2025 |
| Cardiff Capital Holdings Limited | Financial services | 2018 |
| Cardiff City Cleaning Limited | Administrative & support | 2022 |
| Cardiff City Development Centres Newport Ltd | Education | 2011 |
| Cardiff Clear Aligners Ltd | Health & social care | 2023 |
| Cardiff Homecare Ltd | Health & social care | 2012 |
| Cardiff Investment Group Ltd | Financial services | 2021 |
| Cardiff Judo Academy CYF | Arts & recreation | 2023 |
| Cardiff Media Limited | Professional & scientific | 2019 |
| Cardiff Mela Limited | Arts & recreation | 2019 |
| Cardiff Mortgage & Financial Solutions Ltd | Financial services | 2026 |
| Cardiff Web Design Ltd | Information & communication | 2013 |
| Cardiffbay Cleaning Services Ltd | Wholesale & retail | 2025 |
| Cardinal Entertainment Ltd | Professional & scientific | 2021 |
| Cardinal Merchandise Ltd | Wholesale & retail | 2024 |
| Cardiomed Reports Limited | Health & social care | 2010 |
| Care Crew Academy Ltd | Education | 2021 |
| Care for the Family | Education | 1997 |
| Care Fusion Limited | Health & social care | 2013 |
| Care Plus Healthcare Limited | Administrative & support | 2014 |
| Carelian LOG Buildings Ltd | Construction | 2014 |
| Carer's Cloud Limited | Administrative & support | 2024 |
| Carescan Limited | Information & communication | 2023 |
| Carestone Limited | Health & social care | 2026 |
| Caretaker Limited | Real estate | 2002 |
| Carew Estates Limited | Administrative & support | 2005 |
| Carfax Management Limited | Households | 2007 |
| Cargo Marketing Limited | Professional & scientific | 2023 |