| C N Stonework Ltd | Construction | 2023 |
| C Walters Heating Services Ltd | Construction | 2022 |
| C&C Shop Limited | Wholesale & retail | 2015 |
| C.J.Copner Ice Cream Vans Limited | Hospitality | 2015 |
| Cable Property Ltd | Real estate | 2024 |
| CAE Ffwrnais Management Company Limited | Real estate | 2023 |
| Caffael Consulting Ltd | Information & communication | 2022 |
| Caligo Colours Limited | Professional & scientific | 2000 |
| Cambrensis Civil Engineering Limited | Construction | 2023 |
| Cambrensis Holdings Limited | Extraterritorial | 2023 |
| Camrowtal Properties Ltd | Real estate | 2020 |
| Canalrace C.I.C. | Arts & recreation | 2016 |
| Cano Barber Shop Ltd | Other services | 2025 |
| Carbon Capture by Communities Ltd | Professional & scientific | 2022 |
| Cardiff Business IT Services Limited | Information & communication | 2013 |
| Cariad Services Ltd | Health & social care | 2019 |
| Cariadwales Ltd | Wholesale & retail | 2017 |
| Carnival Street Food Ltd | Hospitality | 2020 |
| Carpanini Group Ltd | Financial services | 2026 |
| Carpanini Retail Ltd | Wholesale & retail | 2026 |
| Carroll and Prichard Limited | Construction | 1933 |
| Cartledge & Co Legal Services Limited | Professional & scientific | 2025 |
| Castle Vista Wealth Management Limited | Administrative & support | 2021 |
| Catalyst Enterprise Consultants Limited | Extraterritorial | 1992 |
| Caterham and Lotus Seven Club Limited | Other services | 2021 |
| Catx Limited | Information & communication | 2024 |
| Cdmj Ltd | Education | 2020 |
| Cedar Tree Brewing Company Ltd | Manufacturing | 2020 |
| Cefn Gwyn Limited | Agriculture & fishing | 2023 |
| Celtic Minibus Limited | Transport & logistics | 2008 |
| Cessxpress Limited | Water & waste | 2002 |
| CET Surgical Ltd | Health & social care | 2025 |
| CFL (Chep) Limited | Construction | 2008 |
| CGD Properties Limited | Real estate | 2020 |
| Chapel Financial Services Limited | Financial services | 2009 |
| Chave & Jackson (Holdings) Limited | Financial services | 2017 |
| Chave and Jackson Limited | Wholesale & retail | 1973 |
| Chesney Ltd | Professional & scientific | 1998 |
| Chesters Wine Merchants Ltd | Wholesale & retail | 2017 |
| CHI Management Limited | Real estate | 2016 |
| Child Focused Children Services Limited | Health & social care | 2013 |
| Child Focused Family Services CIC | Health & social care | 2025 |
| Children's Specialist Therapy Ltd | Health & social care | 2012 |
| Chinese Manufacturing Solutions Ltd | Information & communication | 2011 |
| Chirunga Limited | Professional & scientific | 1999 |
| Chockshop UK Limited | Wholesale & retail | 2018 |
| Chris Morrison Limited | Professional & scientific | 2012 |
| Chris Williams Consulting Limited | Professional & scientific | 2012 |
| Christopher T Jenkins Limited | Administrative & support | 2015 |
| Chroma Cars Limited | Wholesale & retail | 2015 |
| Cibicoffee Ltd | Hospitality | 2025 |
| Citrusworld Limited | Professional & scientific | 1979 |
| CJ Maintenance South Wales Ltd | Other services | 2019 |
| Claremont Hall Management Company Limited | Households | 2014 |
| Clarke Ground Maintenance Ltd | Agriculture & fishing | 2025 |
| Classified Tuning Limited | Other services | 2017 |
| Clydach Cambrian Ltd | Hospitality | 2020 |
| Coast & Country Wealth Management Limited | Financial services | 2015 |
| Cocoon Quality Homes Ltd | Construction | 2021 |
| Codebarn Ltd | Information & communication | 2023 |
| Codi International Limited | Wholesale & retail | 2003 |
| Coed Y Fenni Ltd | Professional & scientific | 2025 |
| Cognosdx Ltd | Professional & scientific | 2024 |
| Coldbrook Ventures Limited | Real estate | 2015 |
| Coleman Investments Limited | Real estate | 1914 |
| Colour Format Ltd | Professional & scientific | 2022 |
| Compassionart Limited | Arts & recreation | 2007 |
| Compassionart Publishing Limited | Arts & recreation | 2007 |
| Concordia Contractors Limited | Construction | 1983 |
| Congruent Consulting Ltd | Professional & scientific | 2025 |
| Control Systems Automation Limited | Manufacturing | 2021 |
| Coolworks AC Services Ltd | Wholesale & retail | 2024 |
| Cooper's Accounting & Business Advice Ltd | Professional & scientific | 2018 |
| Copner Biotech Ltd | Professional & scientific | 2020 |
| Copner Solutions Ltd | Information & communication | 2018 |
| Cornelius Capital Limited | Construction | 2023 |
| Cornelius Consultancy Services Limited | Professional & scientific | 2020 |
| Cosy Throws Limited | Wholesale & retail | 2021 |
| Counterweight Limited | Health & social care | 2018 |
| Countrywide Static Caravans Ltd | Wholesale & retail | 2021 |
| County Motors (Lanes) Limited | Professional & scientific | 2013 |
| Craig Abdie Autos Limited | Wholesale & retail | 2020 |
| Craig Parry Diagnostics Limited | Health & social care | 2017 |
| Cranfield Colours Limited | Manufacturing | 1976 |
| Crash Productions Ltd | Information & communication | 2021 |
| Crawshay Solutions Ltd | Information & communication | 2022 |
| Creatively Impatient Consultancy Ltd | Information & communication | 2014 |
| Creature Creative Consulting Ltd | Arts & recreation | 2023 |
| Crewbook Recruitment and Crew Management Agency Ltd | Administrative & support | 2025 |
| Crewkerne Sushi Ltd | Hospitality | 2025 |
| Croftstone Limited | Hospitality | 2023 |
| Crofty Growers Limited | Agriculture & fishing | 1997 |
| Crofty Investments Limited | Financial services | 2024 |
| Crucorney Allotment Society Ltd. | Agriculture & fishing | 2011 |
| Crucorney Woodland Group Community Interest Company | Other services | 2018 |
| CS Grab Hire and Groundworks Ltd | Administrative & support | 2016 |
| CS Grab Hire Ltd | Water & waste | 2023 |
| Cultural Liaisons Ltd. | Education | 1997 |
| Curious Rabbit Ltd. | Manufacturing | 2019 |
| Custodian Wealth Ltd | Financial services | 2017 |