| Capital Unplugged Limited | Professional & scientific | 2017 |
| Capital Upvc Limited | Construction | 2005 |
| Capital Wall Coatings Ltd | Administrative & support | 2019 |
| Capital Wealth Management Ltd | Manufacturing | 2022 |
| Capitalfishcardiff Ltd | Hospitality | 2023 |
| Capitis Global Consultants Limited | Information & communication | 2018 |
| Capitol Business Advisors Ltd | Professional & scientific | 2025 |
| Capitol Residential Ltd | Hospitality | 2019 |
| Capitoles Group PC | | 2017 |
| Caplain Enterprise Limited | Wholesale & retail | 2023 |
| Cappo Ltd | Other services | 2024 |
| Cappuccino Ltd | Hospitality | 2016 |
| Caprency Limited | Professional & scientific | 2019 |
| Capri Cafe Limited | Hospitality | 2023 |
| Capricorn Venture Ltd | Information & communication | 2025 |
| Capsizing Creative Limited | Information & communication | 2020 |
| Capstone Bond Ltd | Health & social care | 2023 |
| Capstone Sports Management Limited | Arts & recreation | 2007 |
| Capsunn Ltd | Administrative & support | 2018 |
| Captain Construction Ltd | Construction | 2019 |
| Captain Joys Ltd | Hospitality | 2020 |
| Captain Limited | Extraterritorial | 2015 |
| Captains Capital Limited | Financial services | 2025 |
| Captains Clubhouse Ltd | Arts & recreation | 2025 |
| Capture and Solve Ltd | Information & communication | 2019 |
| Capucine Digital Limited | Other services | 2017 |
| Car & Commercial Cardiff Ltd | Wholesale & retail | 2024 |
| Car Badges UK Ltd | Wholesale & retail | 2024 |
| Car Clearance Limited | Wholesale & retail | 2018 |
| Car Driving Lessons Harrow Ltd | Education | 2020 |
| Car Finance Experts Limited | Financial services | 2019 |
| Car Mode Ltd | Wholesale & retail | 2025 |
| Car Park 2015 Limited | Transport & logistics | 1989 |
| Car Parking Ltd | Transport & logistics | 2017 |
| Car Plug Ltd | Wholesale & retail | 2019 |
| Car Rise Ltd | Wholesale & retail | 2018 |
| Car Silv Ltd | Transport & logistics | 2019 |
| Car Store London Limited | Wholesale & retail | 2019 |
| Car Swapia Ltd | Wholesale & retail | 2015 |
| Car Tech (Cardiff) Ltd | Wholesale & retail | 2019 |
| Car Threads Ltd | Manufacturing | 2024 |
| Car Trans Wales Europe Ltd | Transport & logistics | 2020 |
| Car Tuning Styling Ltd | Wholesale & retail | 2012 |
| Car U Dream Ltd | Wholesale & retail | 2019 |
| Car Wash (Edgware) Ltd | Administrative & support | 2020 |
| Car-O-Fair Ltd | Wholesale & retail | 2023 |
| Caradena Ltd | Health & social care | 2025 |
| Carafrica Exports Ltd | Wholesale & retail | 2025 |
| Caramics Ltd | Wholesale & retail | 2020 |
| Caraquip Motorhomes Barry Ltd | Wholesale & retail | 2026 |
| Carazza Ltd | Wholesale & retail | 2025 |
| Carbis Bidco Limited | Financial services | 2025 |
| Carbis Holdco Limited | Financial services | 2025 |
| Carbis Midco 1 Limited | Financial services | 2025 |
| Carbis Midco 2 Limited | Financial services | 2025 |
| Carbis Topco Limited | Financial services | 2025 |
| Carbomo UK Ltd | Manufacturing | 2017 |
| Carbon Asset Management Ltd | Wholesale & retail | 2024 |
| Carbon Cars and Classics Limited | Wholesale & retail | 2026 |
| Carbon Catch Limited | Energy | 2013 |
| Carbon Content Ltd | Wholesale & retail | 2024 |
| Carbon Ledger Limited | Information & communication | 2024 |
| Carbon Neutral Homes Ltd | Construction | 2019 |
| Carbon Neutral Investors (UK) Limited | Agriculture & fishing | 2022 |
| Carbon Studio Limited | Professional & scientific | 2007 |
| CARBON99 Ltd | Information & communication | 2021 |
| Carbri Clothing Ltd | Wholesale & retail | 2026 |
| Carbuncle Housing and Managment Ltd | Administrative & support | 2019 |
| Carcloudsconnected Limited | Professional & scientific | 2026 |
| Carcloudsgroup Ltd | Wholesale & retail | 2024 |
| Card and PIN Ltd | Wholesale & retail | 2019 |
| Cardarelli Group Services UK Ltd | Financial services | 2025 |
| Cardboard Castle Collectables & Co. Cyfyngedig | Wholesale & retail | 2025 |
| Cardiff & Central Properties Limited | Real estate | 1987 |
| Cardiff & Glamorganshire Properties Ltd | Real estate | 1885 |
| Cardiff & Vale Blinds Ltd | Wholesale & retail | 2007 |
| Cardiff & Vale Maintenance Contractors Ltd | Administrative & support | 2025 |
| Cardiff & Vale of Glamorgan Parents Federation (Learning Disabilities) | Health & social care | 1995 |
| Cardiff & Vale Valeters Ltd | Administrative & support | 2024 |
| Cardiff Academic Press Limited | Information & communication | 1993 |
| Cardiff Academy Ltd | Education | 2025 |
| Cardiff Accident Repair Solutions Ltd | Wholesale & retail | 2026 |
| Cardiff Accountants Ltd | Professional & scientific | 2022 |
| Cardiff Acquisitions Ltd | Real estate | 2019 |
| Cardiff Aggregates Limited | Transport & logistics | 2021 |
| Cardiff AI Limited | Information & communication | 2023 |
| Cardiff Air Cargo Handling Limited | Transport & logistics | 2025 |
| Cardiff Airport Transfers Ltd | Transport & logistics | 2024 |
| Cardiff Analytica Ltd | Information & communication | 2018 |
| Cardiff and Vale Access Ltd | Construction | 2025 |
| Cardiff and Vale Action for Mental Health | Information & communication | 2012 |
| Cardiff and Vale Developments Ltd | Construction | 2024 |
| Cardiff and Vale Group Ltd | Financial services | 2024 |
| Cardiff and Vale Home Improvements Ltd | Construction | 2026 |
| Cardiff and Vale Roofing Building Ltd | Construction | 2026 |
| Cardiff and Vale Roofing Ltd | Construction | 2022 |
| Cardiff and Vale Tutors Limited | Extraterritorial | 2019 |
| Cardiff Animation Festival C.I.C. | Information & communication | 2018 |
| Cardiff App Developers Limited | Information & communication | 2010 |
| Cardiff Archives Limited | Professional & scientific | 2007 |