| Calon Films Ltd | Information & communication | 2024 |
| Calon Y Cymoedd Ltd | Health & social care | 2020 |
| Calonnau Bach CYF | Health & social care | 2018 |
| Camau Training and Consultancy Ltd | Education | 2019 |
| Cambrian & Co Limited | Professional & scientific | 2011 |
| Cambrian Events & Life Training Limited | Education | 2019 |
| Cambridge Recovery Services Limited | Professional & scientific | 2007 |
| Campbell & Page Consultancy Services Limited | Hospitality | 1999 |
| Camps Transport & Logistics Ltd | Transport & logistics | 2019 |
| Canalside Residents Association CIC | Other services | 2020 |
| Cann Office Ltd | Hospitality | 2013 |
| Cannock Pallets Limited | Transport & logistics | 2018 |
| Carbon Property Partners Ltd | Real estate | 2026 |
| Cardboard Courier Limited | Transport & logistics | 2019 |
| Cardiff Building Company Limited | Real estate | 2024 |
| Care 4 U (Holdings) Limited | Hospitality | 2019 |
| Care 4 U (Neath) Limited | Hospitality | 2008 |
| Care Standard Consultancy Limited | Professional & scientific | 2021 |
| Cared Care Limited | Health & social care | 2017 |
| Caredirectagency Ltd | Administrative & support | 2025 |
| Cariad Bwyd Ltd | Manufacturing | 2025 |
| Cariad Care Services Limited | Health & social care | 2021 |
| Carl Hendy Limited | Construction | 2013 |
| Carla Catering Services Ltd | Hospitality | 2019 |
| Carmarthenshire K9 Fertility Clinic & Dog Store Ltd | Wholesale & retail | 2021 |
| Carmichael Custom Travel Ltd | Administrative & support | 2023 |
| Carter LEE Financial Services Limited | Financial services | 2014 |
| Cartify 360 Limited | Hospitality | 2024 |
| Cartref Home Pet Care Ltd | Professional & scientific | 2026 |
| Casa DE Vino Limited | Hospitality | 2024 |
| Castell Nedd Gardening Ltd | Administrative & support | 2025 |
| Castels Restaurants Ltd | Hospitality | 2022 |
| Castle Carpentry Limited | Construction | 2016 |
| Castle Quay (Neath) Management Limited | Households | 1993 |
| Castle Stone Limited | Mining & quarrying | 2015 |
| Catherine Orton Advisory Limited | Information & communication | 2013 |
| Catherine Sharon Hughes Ltd | Extraterritorial | 2022 |
| Catwg Childcare Club Ltd | Health & social care | 2026 |
| Cavcorn Limited | Hospitality | 2016 |
| Cavi Clear Ltd | Construction | 2018 |
| CC Safety Management Ltd | Professional & scientific | 2022 |
| CCP Transport (Neath) Limited | Transport & logistics | 2022 |
| CD Enhance Holdings Ltd | Real estate | 2018 |
| Ceffyl Coch Stables and Livery Ltd | Agriculture & fishing | 2025 |
| Cefn Management Ltd | Extraterritorial | 2014 |
| Celtic Freeport Company Limited | Other services | 2023 |
| Celtic Furniture Installations Ltd | Construction | 2023 |
| Celtic Lodge (Cimla) Limited | Hospitality | 2014 |
| Celtic Motorcycles Limited | Wholesale & retail | 2011 |
| Celtic Stays Ltd | Hospitality | 2024 |
| Celtic Trailers Limited | Administrative & support | 1982 |
| CEM Services Limited | Construction | 2020 |
| Ceri Charles Davies Ltd | Extraterritorial | 2024 |
| Ceri Davies, HV & Substation Services Limited | Other services | 2015 |
| Chandracore Power Limited | Manufacturing | 2025 |
| Changing Corporate Culture Ltd | Professional & scientific | 2024 |
| Chargepoint Solutions Ltd | Construction | 2021 |
| Charred Street Kitchen Ltd | Hospitality | 2025 |
| Chart House Property Group Limited | Hospitality | 2026 |
| Cheap Financial Claims Limited | Financial services | 2014 |
| Cheslin Group Limited | Construction | 2023 |
| Chic UPH Ltd | Manufacturing | 2015 |
| Child & Adult Support Services C.I.C. | Health & social care | 2017 |
| China 88 Limited | Hospitality | 2012 |
| CHP 20 Ltd | Administrative & support | 2019 |
| Chris Ball Ltd | Professional & scientific | 2023 |
| Chris Taylor Property Ltd | Real estate | 2025 |
| Chrisina Limited | Professional & scientific | 2015 |
| Cimla Forge Ltd | Manufacturing | 2014 |
| City EAT Drink Enjoy Limited | Hospitality | 2013 |
| CJ & Company Holdings Limited | Financial services | 2025 |
| CJ Properties (Neath) Limited | Households | 2022 |
| CJD Property Holdings Limited | Real estate | 2022 |
| CJO Consultancy Limited | Professional & scientific | 2018 |
| Ckem Healthcare, Training and Recruitment Ltd | Administrative & support | 2018 |
| Cladding Technology Ltd | Construction | 2023 |
| Clarian Hope Limited | Administrative & support | 2007 |
| Clarke Brothers Property Ltd | Real estate | 2017 |
| Clarke Brothers Property Solutions Ltd | Construction | 2018 |
| Class ACT Tutoring Ltd | Education | 2024 |
| Classic Lions Limited | Arts & recreation | 2019 |
| Classic Rugby Limited | Arts & recreation | 2019 |
| Clear CUT Social Ltd | Information & communication | 2017 |
| Clearstone Exterior Solutions Ltd | Administrative & support | 2026 |
| CLH Brickwork Ltd | Construction | 2026 |
| Clifty Limited | Professional & scientific | 2020 |
| Clio Barbers Ltd | Other services | 2017 |
| Cloud Optimisation Ltd | Professional & scientific | 2022 |
| Club of Jacks Ltd | Households | 2025 |
| CM Nest Ltd | Construction | 2025 |
| Cmack Solutions Ltd | Administrative & support | 2025 |
| CMJ Enterprise Ltd | Administrative & support | 2012 |
| Coco Blush Boutique Limited | Administrative & support | 2020 |
| Coconut Bricks Limited | Real estate | 2023 |
| Cocos Boutiques 12 Ltd | Wholesale & retail | 2025 |
| Cocos Boutiques Ltd | Wholesale & retail | 2017 |
| Coda Associates Ltd | Professional & scientific | 2018 |
| Codepress Ltd | Information & communication | 2023 |
| Coed Darcy Bowls Club CIC | Education | 2026 |
| Coker Thomas Holdings Ltd | Financial services | 2026 |