| Cardigan Rail Services Ltd | Construction | 2014 |
| Cardigan Sand and Gravel Company Limited | Mining & quarrying | 1959 |
| Care Wales (Gofal Cymru) Limited | Health & social care | 2013 |
| Careg Ltd | Construction | 2025 |
| Cariad Homes Limited | Construction | 2025 |
| Caring Companionship Ltd | Health & social care | 2014 |
| Caring Voice Limited | Health & social care | 2022 |
| Carpyman Ltd | Construction | 2025 |
| Cartrefi Deri Homes Limited | Construction | 2010 |
| Cartrefi Ffosaron Homes Limited | Construction | 2002 |
| Cartrefi JDW CYF | Extraterritorial | 2010 |
| Caws Cenarth Cheese Holdings Limited | Financial services | 2022 |
| Cela Associates Ltd. | Professional & scientific | 2017 |
| Celtic House EOT Trustee Limited | Professional & scientific | 2026 |
| Celtic House Holdings Limited | Financial services | 2026 |
| Celtic Sustainables Limited | Construction | 2000 |
| Ceredigion Leisure Limited | Arts & recreation | 2000 |
| Cerys Jones Ltd | Education | 2010 |
| Child of the Earth CIC | Education | 2023 |
| Cilgerran Coracle Festive Committee Ltd | Arts & recreation | 2023 |
| Clare Lawn Investments Limited | Real estate | 2023 |
| Clunderwen Stores Limited | Wholesale & retail | 2006 |
| Clwb Golff Aberteifi CYF | Extraterritorial | 2021 |
| Clwb Golff Aberteifi Masnachu CYF | Arts & recreation | 2021 |
| Clwb Rygbi Aberteifi CYF | Arts & recreation | 2023 |
| Clynfyw Community Interest Company | Education | 2011 |
| Clynfyw Countryside Centre Ltd. | Hospitality | 1999 |
| Coast Caravans Ltd | Wholesale & retail | 2016 |
| Coast WS Limited | Information & communication | 2022 |
| Coastal Fire Safety Ltd | Public administration | 2026 |
| Coedmor Ltd | Information & communication | 2026 |
| Coedmor Mansion Management Company Limited | Real estate | 1987 |
| Coleg Ceredigion | Education | 2013 |
| Colin Phillips Funerals Limited | Other services | 2007 |
| Commonground Group Ltd | Professional & scientific | 2024 |
| Communis Limited | Information & communication | 1996 |
| Conscious Skincare Limited | Wholesale & retail | 2019 |
| Consulting AM Ltd | Professional & scientific | 2008 |
| Coratec Limited | Administrative & support | 2023 |
| Corbett Williams & SON Limited | Wholesale & retail | 1982 |
| Coreceltic Limited | Construction | 2026 |
| Corvus Leisure LLP | | 2020 |
| Crab Club Horizons CIC | Manufacturing | 2025 |
| Crab Club Ltd | Manufacturing | 2025 |
| Crathorne Consultancy Ltd | Professional & scientific | 2018 |
| Cresent Construction Limited | Construction | 2014 |
| Crisp Coaching and Consultancy Limited | Professional & scientific | 2005 |
| Cross Over Gym Limited | Other services | 2009 |
| Crosslyn Garage Ltd | Wholesale & retail | 2005 |
| Crwst Limited | Hospitality | 2017 |
| Crymych GAS Limited | Wholesale & retail | 2024 |
| CTP Storage Solutions Ltd | Transport & logistics | 2026 |
| Cynilion Teifi Savings CYF | Financial services | 2024 |
| D & G James Developments Limited | Construction | 2003 |
| D J Evans Plumbing & Heating Limited | Construction | 2020 |
| D M B Davies Limited | Professional & scientific | 2005 |
| D Williams Building & Roofing Services Ltd | Construction | 2002 |
| DAI Hughes Limited | Construction | 2003 |
| Damage Designs Ltd | Manufacturing | 2012 |
| Davfam Ltd | Hospitality | 2023 |
| David Brown Travel (Wales) Ltd | Wholesale & retail | 2013 |
| David Davies Land Holdings Ltd | Construction | 2017 |
| David Davies Management Services Ltd | Agriculture & fishing | 2006 |
| David Postance & SON Ltd | Agriculture & fishing | 2010 |
| Daystar Foods Ltd | Hospitality | 2026 |
| DD & CM Jones Limited | Agriculture & fishing | 2006 |
| Dechrau Newydd Limited | Wholesale & retail | 2010 |
| Dewi James A'I Gwmni CYF | Wholesale & retail | 2022 |
| Diamond Interior Furnishing Limited | Manufacturing | 2010 |
| DO Radio Co Limited | Information & communication | 2025 |
| Dol-Y-Dintir Limited | Households | 2009 |
| Don'T Look NOW Limited | Professional & scientific | 2014 |
| DPE Builders Limited | Construction | 2013 |
| Dreamdayz Creations Ltd | Wholesale & retail | 2013 |
| Drovers Glamping Limited | Hospitality | 2023 |
| DWR Penceibwr Water Limited | Manufacturing | 2025 |
| DWUKWELDER86 Ltd | Construction | 2017 |
| Dyffryn Teifi Developments Limited | Construction | 2019 |
| E L Jones A'I FAB CYF | Manufacturing | 2006 |
| E W Owen Limited | Professional & scientific | 2006 |
| E.Garfield Jones and SON Limited | Hospitality | 1961 |
| Eccentric Spirit Co Ltd | Manufacturing | 2020 |
| Eco PC Limited | Other services | 2009 |
| ED Davies Limited | Wholesale & retail | 2005 |
| ED Griffiths & Co. Limited | Agriculture & fishing | 2005 |
| EL Salsa Limited | Hospitality | 2021 |
| Elderworld Studios Ltd | Arts & recreation | 2023 |
| Electro Avionics Ltd | Extraterritorial | 2013 |
| Electro Brewing Ltd | Manufacturing | 2019 |
| Embodied Spirit Ltd | Health & social care | 2021 |
| Emsspar Limited | Wholesale & retail | 2005 |
| Enker Limited | Hospitality | 2025 |
| Envisager Limited | Professional & scientific | 2003 |
| Equal Women CIC | Other services | 2021 |
| Every Mobile Limited | Extraterritorial | 2010 |
| Exportaction Limited | Professional & scientific | 2009 |
| Fantasy Park Ltd | Information & communication | 2022 |
| Feral Energy Limited | Energy | 2015 |
| Ffabweld Limited | Manufacturing | 2021 |
| Ffenestri GD Windows Ltd | Construction | 2026 |