| BWB Life Ltd | Hospitality | 2021 |
| BWE Property Limited | Real estate | 2022 |
| Bwthyn Teulu Ltd | Real estate | 2020 |
| Byzon Limited | Information & communication | 2021 |
| C Cubed Homes Ltd | Real estate | 2017 |
| C L Training Services Limited | Education | 2005 |
| C M Interiors Limited | Professional & scientific | 2025 |
| C Matthews Construction Ltd | Construction | 2025 |
| C&E Pets Ltd | Wholesale & retail | 2025 |
| C&J Evans Group Holdings 1 Ltd | Financial services | 2021 |
| C. P. General Services Limited | Construction | 2001 |
| C.C.P.Fencing Specialists Limited | Construction | 1948 |
| C.P.S. (Wales) Limited | Manufacturing | 1995 |
| C365 Construction Ltd | Wholesale & retail | 2026 |
| Caasta Limited | Administrative & support | 2019 |
| Cadarn Access Limited | Construction | 2025 |
| Cadre Recruitment Limited | Administrative & support | 2023 |
| Cadwaladers (Cardiff) Limited | Hospitality | 2015 |
| Cadwaladers (Retail) Limited | Hospitality | 2015 |
| Caer Enfys Property Management Company Limited | Households | 2019 |
| Caerffili Eats Limited | Hospitality | 2026 |
| Caerphilly Barbers Ltd | Other services | 2020 |
| Caerphilly Blenders Limited | Extraterritorial | 2005 |
| Caerphilly Carpet & Flooring Limited | Construction | 2019 |
| Caerphilly Chinese Limited | Hospitality | 2025 |
| Caerphilly Cloud Ltd | Wholesale & retail | 2023 |
| Caerphilly Community Gym CIC | Health & social care | 2019 |
| Caerphilly Eco Hub CIC | Education | 2022 |
| Caerphilly Equipment Hire Limited | Administrative & support | 2025 |
| Caerphilly Garden Centre Limited | Wholesale & retail | 1983 |
| Caerphilly Lettings Limited | Real estate | 2024 |
| Caerphilly Market Ltd | Wholesale & retail | 2019 |
| Caerphilly Media Ltd | Information & communication | 2011 |
| Caerphilly Miners Centre for the Community | Arts & recreation | 2011 |
| Caerphilly Nails and Beauty Ltd | Other services | 2025 |
| Caerphilly Opticians Limited | Wholesale & retail | 2006 |
| Caerphilly Phones Ltd | Information & communication | 2019 |
| Caerphilly Plumbing and Heating Limited | Construction | 1973 |
| Caerphilly Regeneration Ltd | Real estate | 2025 |
| Caerphilly Rugby Limited | Arts & recreation | 2023 |
| Caerphilly Service Centre Limited | Wholesale & retail | 2025 |
| Caerphilly Skip Hire (CWS) Ltd | Water & waste | 2009 |
| Caerphilly Sports Supplements Ltd | Wholesale & retail | 2021 |
| Caerphilly Station Chiropractic Centre Limited | Health & social care | 2005 |
| Caerphilly Uniform Exchange CIC | Wholesale & retail | 2022 |
| Caerphilly Valley Garden Ltd | Hospitality | 2024 |
| Caerphilly Veterans Support Hub CIC | Health & social care | 2025 |
| Caerphilly Welding Services Ltd | Manufacturing | 2016 |
| Cakes by HIM Ltd | Manufacturing | 2022 |
| Calabria 18 Limited | Hospitality | 2018 |
| Callowgate Limited | Professional & scientific | 1973 |
| Calon AI Solutions Limited | Information & communication | 2024 |
| Calon Law Limited | Professional & scientific | 2021 |
| Calveds Consultancy Limited | Professional & scientific | 2026 |
| Cambrian Energy Ltd | Administrative & support | 2018 |
| Cambrian Offshore Ltd | Administrative & support | 2018 |
| Camilleri Properties Ltd | Real estate | 2023 |
| Candlelight Information Systems Limited | Information & communication | 1998 |
| CAP Renovations Cardiff Ltd | Construction | 2022 |
| Capital Chef 168 Ltd | Hospitality | 2026 |
| Capital Cuisine Catering Services Limited | Manufacturing | 2006 |
| Capital Screeders Limited | Construction | 2003 |
| Captiva Spa and Lounge Ltd | Wholesale & retail | 2008 |
| Carabiner IT Limited | Professional & scientific | 2015 |
| Caravan and Motorhome Services Limited | Manufacturing | 2007 |
| Carbis Moor Regeneration Ltd | Real estate | 2020 |
| Carbonrite Limited | Professional & scientific | 2026 |
| Cardiff PAT Test Ltd | Professional & scientific | 2020 |
| Cardiff Steel Erection Limited | Administrative & support | 2005 |
| Care One 2 One Ltd | Health & social care | 2012 |
| Carnival Content Ltd | Information & communication | 2019 |
| Carpenterseye Ltd | Construction | 2024 |
| Casa MIA Ristorante Italiano Limited | Hospitality | 2016 |
| Casalaia Ltd | Real estate | 2021 |
| Cascade First AID Ltd | Education | 2020 |
| Casey the Band Ltd | Information & communication | 2022 |
| Cashman Haulage Ltd | Transport & logistics | 2022 |
| Cashman Properties Ltd | Households | 2024 |
| Castell Cars Limited | Transport & logistics | 2002 |
| Castle Coatings (Holdings) Limited | Financial services | 2019 |
| Castle Coatings Limited | Manufacturing | 2005 |
| Castle Dairies Limited | Manufacturing | 1986 |
| Castle Heights Golf Ltd | Arts & recreation | 2024 |
| Castle Mechanical Services Ltd | Construction | 2016 |
| Castle Park Developments Limited | Construction | 2013 |
| Castle Superstore SW Ltd | Wholesale & retail | 2025 |
| Castle Tyres Caerphilly Ltd | Wholesale & retail | 2025 |
| Castlegate (Nantgarw) Ltd | Hospitality | 2016 |
| Cays Ltd | Construction | 2025 |
| Cbehx Ltd | Professional & scientific | 2019 |
| CBT Illustrations Limited | Arts & recreation | 2012 |
| CBW Flooring Supplies Limited | Construction | 2022 |
| CDH Contractors Ltd | Construction | 2017 |
| CDH Surveying Ltd | Real estate | 2020 |
| CDW Electrical Ltd | Construction | 2019 |
| CEH Management Ltd | Financial services | 2018 |
| Celtech Consultancy Limited | Professional & scientific | 2004 |
| Celtic Construction Services Limited | Construction | 2025 |
| Celtic Horizons Limited | Manufacturing | 2011 |
| Celtic Landscaping and Living Spaces Ltd | Administrative & support | 2025 |