| C S M & Facilities Group Ltd | Administrative & support | 2025 |
| C&G GAS Services Limited | Construction | 2023 |
| C&G Motorcycles Ltd | Wholesale & retail | 2021 |
| C&G Tyres Ltd | Wholesale & retail | 2016 |
| C&L Contract Cleaning Limited | Construction | 2013 |
| C. G. Vimpany Limited | Construction | 2006 |
| C.& E.Lewis(Properties)Limited | Real estate | 1964 |
| C.A.R. Dismantlers Limited | Professional & scientific | 2008 |
| C.E. Green (Eddis) and Sons Ltd | Construction | 2025 |
| C.L. Jeffries Limited | Wholesale & retail | 1992 |
| C.L.A.D. Right Industrial Roofing & Cladding Limited | Construction | 2006 |
| Cable Monkey Ltd | Manufacturing | 2024 |
| Caerau Developments Ltd. | Construction | 2014 |
| Cafe Zara Limited | Hospitality | 2023 |
| Caitlyn JIM Limited | Health & social care | 2025 |
| Caldylell Design Limited | Financial services | 2023 |
| Camborne Consult Limited | Professional & scientific | 2025 |
| Cambrian Fuelcard Services Limited | Wholesale & retail | 1976 |
| Can'T BE Asked Solutions Limited | Real estate | 2006 |
| Candy Enterprises Limited | Hospitality | 2021 |
| Cantelo Company Limited | Real estate | 2025 |
| Cantelo Group Holdings Ltd | Financial services | 2025 |
| Capital Windscreens & Bodyglass Ltd | Wholesale & retail | 2014 |
| Capstone Recruitment Limited | Administrative & support | 2007 |
| Capture the Moment Limited | Professional & scientific | 2009 |
| Car Auto Salvage Ltd | Other services | 2017 |
| Car Body Work Specialist Ltd | Wholesale & retail | 2009 |
| Carefulai Ltd | Information & communication | 1999 |
| Carreg Fawr Developments Limited | Manufacturing | 1988 |
| Cashmere London Ltd | Wholesale & retail | 2025 |
| Caspian Newport Ltd | Hospitality | 2023 |
| Castell Heights Limited | Hospitality | 2026 |
| Castell View Ltd | Hospitality | 2024 |
| Castra Estate Planning Limited | Financial services | 2021 |
| Castra Financial Limited | Financial services | 2019 |
| Catenius Ltd | Professional & scientific | 2019 |
| Catering Source Ltd | Hospitality | 2009 |
| Cathays Properties LLP | | 2018 |
| Catherineallencare Ltd | Health & social care | 2025 |
| Cavill Property Investments Ltd | Real estate | 2022 |
| CB Training Services Limited | Education | 2009 |
| Cbuildr Limited | Construction | 2021 |
| Celtic Bait Limited | Agriculture & fishing | 2021 |
| Celtic Cabins Limited | Hospitality | 2024 |
| Celtic Security Management Ltd | Administrative & support | 2020 |
| Celtic Security Training Centre Limited | Administrative & support | 2024 |
| Cementorious Construction Ltd | Construction | 2020 |
| Centre for Intelligent Design Ltd | Information & communication | 2019 |
| Centric Global Limited | Professional & scientific | 2007 |
| Cerebrox Labs Ltd | Professional & scientific | 2024 |
| CFM Property Estates Ltd | Real estate | 2024 |
| Cften Limited | Manufacturing | 2007 |
| Cgmt Limited | Agriculture & fishing | 2014 |
| Champion Holdings and Management Ltd | Financial services | 2022 |
| Champion Vans Ltd | Wholesale & retail | 2018 |
| Chans Noodles Ltd | Hospitality | 2024 |
| Chantellerichards Ltd | Wholesale & retail | 2025 |
| Chapel Antiques and Collectables Limited | Wholesale & retail | 2005 |
| Chapel Street Motors Ltd | Wholesale & retail | 2020 |
| Charlotte Alexander Bridal Ltd | Wholesale & retail | 2019 |
| Chase Cards Ltd | Wholesale & retail | 2025 |
| Cheeky Monkeys (Cwmbran) Limited | Education | 2007 |
| Cheryl-Anne Properties Ltd | Real estate | 2025 |
| Cheshire Estate Agents (SW) Limited | Real estate | 2019 |
| Cheshire Estate Agents Limited | Real estate | 2011 |
| Cheshire Homes (SW) Limited | Real estate | 2020 |
| Chic Beauty Newport Ltd | Other services | 2016 |
| Choose Solution Ltd | Construction | 2025 |
| Chorlton Financial Ltd | Professional & scientific | 2018 |
| Chris Jones Crop Care Limited | Agriculture & fishing | 2019 |
| Cinjem Limited | Professional & scientific | 2021 |
| CJL Electrical Solutions Ltd | Construction | 2019 |
| CJM Aesthetics Ltd | Other services | 2020 |
| CJS Property Maintenance Limited | Construction | 2014 |
| CJT Mechanical Engineering Services Limited | Other services | 2006 |
| CK Electrical Ltd | Construction | 2017 |
| CKY Holdings Limited | Real estate | 2024 |
| Classer Ltd | Manufacturing | 2024 |
| CLB Gaspro Ltd | Construction | 2026 |
| Clear (Holdings) Limited | Financial services | 2014 |
| Clic IT Flooring Limited | Construction | 2015 |
| Clic IT Management Ltd | Construction | 2025 |
| Close Consultants Limited | Administrative & support | 2024 |
| Clothing View Ltd | Wholesale & retail | 2023 |
| Clynderwen Farm Dairy Limited | Agriculture & fishing | 2022 |
| CM Waste Collections Wales Ltd | Water & waste | 2024 |
| Coastal & Country Hideaways Limited | Real estate | 2023 |
| Coburn Technologies Limited | Wholesale & retail | 2010 |
| Coffi Kitoko Ltd | Wholesale & retail | 2022 |
| Cold Shelter Ltd | Manufacturing | 2023 |
| Coldstream Limited | Construction | 2013 |
| Coleg QS Limited | Administrative & support | 2007 |
| Coleson Homes Ltd | Real estate | 2025 |
| Combi-Nation Boiler Install , Repairs & Servicing Ltd | Construction | 2023 |
| Commandvault Group Ltd | Information & communication | 2025 |
| Commissioning Strategies Limited | Professional & scientific | 2010 |
| Complete Bathrooms Limited | Construction | 1995 |
| Complete Kitchens Limited | Construction | 1996 |
| Complete Weed Control (South and Central Wales) Ltd | Other services | 1994 |
| Complete Weed Limited | Other services | 2015 |