| Caleb Technical Limited | Wholesale & retail | 1997 |
| Calloway Bookkeeping Limited | Professional & scientific | 2020 |
| CAM Body Repairs Ltd | Wholesale & retail | 2019 |
| Cam-C Holdings Limited | Administrative & support | 2018 |
| Capel Hill Stores Limited | Wholesale & retail | 2017 |
| Cara John Colours Limited | Other services | 2025 |
| Caras Colours Ltd | Other services | 2024 |
| Cariad Renovations Ltd | Construction | 2023 |
| Carjolems Ltd | Health & social care | 2018 |
| Carl Richardson Services Limited | Construction | 2018 |
| Cartefi CWM Hyfryd Ltd | Real estate | 2025 |
| Caru TI Limited | Extraterritorial | 2013 |
| Castlegate 618 Limited | Real estate | 2010 |
| CCL - Custom Carpentry & Landscaping Ltd | Manufacturing | 2020 |
| CD Projects Ltd | Real estate | 2025 |
| Cedar Wood Law Limited | Professional & scientific | 2025 |
| Celtic Hill Ltd | Real estate | 2024 |
| Centric Home Improvements Limited | Construction | 2017 |
| Centric Silicone Render Systems Ltd | Construction | 2025 |
| Centric Wall Coatings Ltd | Construction | 2022 |
| Certus Accountancy & Bookkeeping Limited | Professional & scientific | 2026 |
| Cerys Logistics Limited | Transport & logistics | 2025 |
| Chapman Property Agent Ltd | Real estate | 2021 |
| Chapman Sales Ltd | Real estate | 2023 |
| Chefs Life Limited | Hospitality | 2018 |
| Chequered Flag (Wales) Limited | Wholesale & retail | 1999 |
| CHL Trading Limited | Wholesale & retail | 2021 |
| Chris Hicks Health Informatics Ltd | Health & social care | 2015 |
| Clarke Construction (South Wales) Ltd. | Wholesale & retail | 2004 |
| Classic Blinds Wales Ltd | Manufacturing | 2008 |
| Classy Data Limited | Hospitality | 2007 |
| Clemco Property Ltd | Real estate | 2026 |
| Clwb Sawna Community Interest Company | Hospitality | 2025 |
| CMS Waste Management Limited | Water & waste | 2024 |
| CNL Properties Limited | Real estate | 2007 |
| Code Complete Consulting Ltd | Information & communication | 2014 |
| Colco Automotive Ltd | Wholesale & retail | 2025 |
| Cole's Kitchen Limited | Manufacturing | 2020 |
| Combust Boiler Services Ltd | Manufacturing | 2019 |
| Connect IT Groundworks Ltd | Construction | 2022 |
| Connectivity Services Limited | Information & communication | 2024 |
| Construction Skills Wales Ltd | Construction | 2023 |
| Contrast Wellness Club Limited | Arts & recreation | 2024 |
| Corner Pizza 19 Ltd | Hospitality | 2025 |
| Cory Bulford Construction Ltd | Construction | 2024 |
| Cory Property Management Ltd | Real estate | 2022 |
| County Roof Care Limited | Construction | 2025 |
| Crafted Spaces Cardiff Limited | Construction | 2025 |
| Crown Brickwork Limited | Construction | 2024 |
| CRW Rail Ltd | Construction | 2018 |
| Crystals Cove Ltd | Wholesale & retail | 2026 |
| Cube Print Limited | Manufacturing | 2005 |
| Curvy Babs Ltd | Professional & scientific | 2026 |
| Cute Nest Builders Ltd | Real estate | 2025 |
| CWM Haven Ltd. | Extraterritorial | 2025 |
| Cwmlai After School Club Ltd | Health & social care | 2022 |
| Cydunedig Ltd | Information & communication | 2026 |
| Cymmer Fish Bar Limited | Hospitality | 2003 |
| D D C Civil Engineering & Construction Limited | Construction | 2013 |
| D N Interiors Limited | Financial services | 2022 |
| DAN Jennings Ltd | Transport & logistics | 2026 |
| Darjen Contractors Ltd. | Construction | 2016 |
| Dark Sky Wales Training Services Limited | Education | 2011 |
| Davies Roofing Contractors Ltd | Construction | 2015 |
| DC10 Limited | Construction | 2018 |
| DE Cymru Cleaning Services Ltd | Administrative & support | 2026 |
| Dean Civils Limited | Construction | 2026 |
| DHT Delivery Services Ltd | Transport & logistics | 2025 |
| Digger Dean Ltd | Construction | 2023 |
| Digital Start C.I.C. | Information & communication | 2025 |
| Ditari AUT Mori Conatur Ltd | Real estate | 2019 |
| Divinate Ltd | Information & communication | 2006 |
| DJ Hogan Farriers Limited | Other services | 2016 |
| DJ Railway Engineering Ltd | Construction | 2016 |
| Dlor Consulting Limited | Professional & scientific | 2025 |
| DNC Protection Limited | Administrative & support | 2019 |
| Doner KNG Pizzanos Ltd | Hospitality | 2018 |
| Draftcopy Limited | Construction | 1998 |
| Dragon Elite Sharpening Services Limited | Other services | 2021 |
| Dragon Inn 838 Limited | Hospitality | 2022 |
| DRC Brickwork Ltd | Construction | 2022 |
| Dreamscape Construction & Design Ltd | Construction | 2021 |
| Drumofheritage Limited | Wholesale & retail | 2026 |
| Dyffryn Homes Limited | Real estate | 2021 |
| Dymmock Heating Ltd | Construction | 2018 |
| Eco Renovations and Recycling Ltd | Construction | 2025 |
| Ecogrid Installations Ltd | Construction | 2025 |
| Edge Taxis Ltd | Transport & logistics | 2026 |
| Edmonds Rail Ltd | Construction | 2018 |
| EJ Civil and Rail Ltd | Construction | 2016 |
| Electrical Safety Inspectors Ltd | Construction | 2021 |
| Elecweb Limited | Wholesale & retail | 2010 |
| Elekem Limited | Manufacturing | 1975 |
| Element Fire Doors Limited | Public administration | 2026 |
| Element Fire Ltd | Public administration | 2024 |
| Elite Carpentry (Wales) Ltd | Construction | 2014 |
| Elite Independent Mortgages Limited | Financial services | 2004 |
| Ells Financial Ltd | Financial services | 2025 |
| Elston & Sons Limited | Other services | 2005 |
| ELY Valley Construction Company Limited | Construction | 1972 |