| Cambrensis Ltd | Administrative & support | 2002 |
| Cambria DMC Limited | Administrative & support | 2018 |
| Cambria Tours Ltd | Administrative & support | 2012 |
| Cambrian Carpentry Limited | Construction | 2024 |
| Cambrian Farm Consultancy Ltd | Professional & scientific | 2023 |
| Cambrian Feed and Fertiliser Ltd | Wholesale & retail | 2021 |
| Cambrian Fencing Limited | Manufacturing | 2004 |
| Cambrian Hotel Ltd | Hospitality | 2014 |
| Cambrian Property Management Limited | Real estate | 2004 |
| Cambrian Tyres Cycle Ltd | Wholesale & retail | 2023 |
| Camddwr Contractors CYF | Administrative & support | 2011 |
| Canis Concept Limited | Other services | 2021 |
| Canningsfba Ltd | Wholesale & retail | 2025 |
| Capel Bangor Homes Ltd | Construction | 2022 |
| Carbon Costed Designs Ltd | Construction | 2017 |
| Cardigan Bay Fishermans Association Limited | Arts & recreation | 2003 |
| Cardigan Bay Holiday Parks Ltd | Hospitality | 2023 |
| Cardigan Bay Properties Limited | Real estate | 2003 |
| Cardigan Bay Watersports | Arts & recreation | 2006 |
| Carpenters Aberystwyth Ltd | Construction | 2023 |
| Carrog Ltd. | Information & communication | 1998 |
| Casavirdi Developments Limited | Real estate | 2020 |
| Catalina Architecture and Design Ltd | Professional & scientific | 2018 |
| CBS MID Wales Limited | Construction | 2015 |
| CBW Property Management Limited | Households | 2019 |
| CCW Solutions Limited | Wholesale & retail | 2010 |
| Cefn Gwlad Solutions Ltd | Other services | 2015 |
| Cefn Hendre Developments Limited | Extraterritorial | 2014 |
| Cegin Punjabi Limited | Hospitality | 2025 |
| Celtic Bay Guest House Limited | Hospitality | 2017 |
| Celtic DUO Construction Ltd | Construction | 2015 |
| Celtic Electrical Ltd | Construction | 2024 |
| Celtic Waste Limited | Water & waste | 2022 |
| Central Fish Restaurant Limited | Hospitality | 2024 |
| Central Wales Football Association Limited | Arts & recreation | 2005 |
| Centre for Performance Research Limited | Arts & recreation | 1988 |
| Ceredigion Accommodations Ltd | Construction | 2011 |
| Ceredigion Cottages Ltd | Hospitality | 2017 |
| Ceredigion Recycling and Furniture Team | Wholesale & retail | 1998 |
| Ceri House Limited | Real estate | 2021 |
| Chantilly Property Management Limited | Real estate | 2022 |
| Charis Industrial Consultants Ltd | Professional & scientific | 2024 |
| Charnock and Vyse Hospitality Ltd | Hospitality | 2017 |
| Chip Box 4 (Penroc) Limited | Hospitality | 2014 |
| Chiyo Limited | Wholesale & retail | 2024 |
| Ciao Ciao Trattoria Ltd | Hospitality | 2022 |
| CIT Clothing Ltd | Wholesale & retail | 2025 |
| Clasica Ltd | Wholesale & retail | 2020 |
| Cleobury Project Management Limited | Professional & scientific | 2022 |
| Clive Continental Menswear Limited | Wholesale & retail | 2013 |
| Clos Megan Management Company Limited | Real estate | 2021 |
| Clos Y Dderwen Flats Limited | Professional & scientific | 2013 |
| Clwb Golff Aberystwyth Golf Club Limited | Arts & recreation | 2011 |
| Coastal Apartments Ltd | Real estate | 2025 |
| Coastline Property Developments Group Limited | Construction | 2026 |
| Codan Bionuclear Ltd | Manufacturing | 2014 |
| Coed Symlog Ltd | Agriculture & fishing | 2024 |
| Coedlan Halls Limited | Real estate | 2023 |
| Coffi a Bara Ltd | Hospitality | 2021 |
| Colab Content Limited | Information & communication | 2026 |
| Constitution Hill Ltd. | Transport & logistics | 1997 |
| Constitution Hill Trading Ltd. | Wholesale & retail | 2005 |
| Coop & PEN Ltd | Hospitality | 2019 |
| Core Services Group Limited | Construction | 2022 |
| Cornerswell Design & Production Ltd | Arts & recreation | 2020 |
| Cosmopolitan Bejewelled Ltd | Wholesale & retail | 2020 |
| Countryside Access Management Limited | Professional & scientific | 2007 |
| Cowfold Hand Car Wash Limited | Other services | 2021 |
| Crossfit Aberystwyth Limited | Arts & recreation | 2013 |
| Crosswood Property Services Limited | Construction | 2006 |
| CS Darlledu Ltd | Information & communication | 2024 |
| CSP Cymru CYF | Information & communication | 2000 |
| Curado Bar Limited | Hospitality | 2016 |
| Cutting Edge (Aberystwyth) Ltd | Construction | 2023 |
| Cwmni Curiad CYF. | Information & communication | 2008 |
| Cwmni Ennyn Awaken Productions | Arts & recreation | 2016 |
| Cwmni Helyg Ltd | Manufacturing | 2025 |
| Cwmni TAI Thomas CYF | Real estate | 2022 |
| Cwrt Aberystwyth CYF | Hospitality | 2023 |
| Cwrt Cennydd CYF | Hospitality | 2012 |
| Cwtchi Ltd | Wholesale & retail | 2015 |
| Cyfraith Ceredigion CYF | Professional & scientific | 2017 |
| Cylch Meithrin Trefeurig | Education | 2012 |
| Cymdeithas CWN Defaid Cymreig | Agriculture & fishing | 1998 |
| Cymdeithas Gofal the Care Society | Hospitality | 2011 |
| Cymdeithas Maes Chwarae Rhydypennau CYF. | Arts & recreation | 2015 |
| Cymdeithas Trigolion Teras Y Glogwyn Cyfyngedig | Households | 1987 |
| Cymro Holdings Ltd | Real estate | 2021 |
| Cynefin Circle CIC | Health & social care | 2026 |
| Cynon Rose Groundworks & Landscaping Ltd | Construction | 2026 |
| Cynyrchiadau Mojo Productions Cyfyngedig | Information & communication | 2024 |
| Cysgod Y Coed Ltd | Health & social care | 2008 |
| D & L Property Developments Limited | Real estate | 2016 |
| D J Howells Ltd | Agriculture & fishing | 2019 |
| D M Food Safety Limited | Professional & scientific | 2024 |
| D M Jones Electrical, GAS and Plumbing Limited | Construction | 2017 |
| D N Davies Builders Limited | Construction | 1999 |
| D.G.D. Machinery Limited | Wholesale & retail | 1998 |
| Danycoed Mansion Residents Association Limited | Households | 1963 |
| Dark Farm Hops Limited | Manufacturing | 2019 |