| Bridges in Social Understanding Limited | Health & social care | 2013 |
| Bridgevale Properties Limited | Real estate | 2000 |
| Brightsky Media Limited | Professional & scientific | 2008 |
| Broadway Bakes Ltd | Manufacturing | 2025 |
| Brynmill Limited | Health & social care | 2013 |
| Bskd Property Limited | Real estate | 2022 |
| BSW Group Holdings Ltd | Financial services | 2025 |
| BT Lindell Contracting Ltd | Financial services | 2023 |
| Bull Solutions Limited | Information & communication | 2016 |
| Burbrew Ltd | Financial services | 2021 |
| Burgess Home & Garden Limited | Wholesale & retail | 2021 |
| Business for Media Limited | Administrative & support | 2013 |
| C L M Construction Limited | Construction | 1990 |
| C T W Properties Ltd | Real estate | 1991 |
| C.Greening Carpentry & Property Maintenance Ltd | Construction | 2020 |
| C.M.M. Bloodstock Limited | Agriculture & fishing | 2004 |
| Caam Professional Services Limited | Professional & scientific | 2019 |
| Caesura Media Limited | Other services | 2015 |
| Cafe & Culture CIC | Administrative & support | 2025 |
| Calan Cyfyngedig | Professional & scientific | 2002 |
| Calon Medical Education CYF | Administrative & support | 2026 |
| Camc Limited | Information & communication | 2012 |
| Cameratech Projects Limited | Construction | 2004 |
| Camso UK Limited | Wholesale & retail | 1991 |
| Canbry Consulting Limited | Professional & scientific | 2008 |
| Carapace Slate Limited | Manufacturing | 2016 |
| Caravan Hospital Limited | Other services | 2024 |
| Carbon Advisory Partners Limited | Professional & scientific | 2010 |
| Carbon Funding Partners Limited | Financial services | 2019 |
| Carbon Health Network Limited | Professional & scientific | 2009 |
| Cardiff Design Company Limited | Professional & scientific | 2018 |
| Carico Advisory Ltd | Professional & scientific | 2025 |
| Carrie Elspeth Ltd | Manufacturing | 2003 |
| Cartrefi Hawen Homes CYF. | Real estate | 2019 |
| Case Management Cymru Ltd | Health & social care | 2015 |
| Cassini Aviation Services Ltd | Manufacturing | 2016 |
| Cedarbrook Limited | Real estate | 2021 |
| CEL Storage Ltd | Transport & logistics | 2025 |
| Celtic Creations Ltd | Real estate | 2020 |
| Celtic Kitchens Ltd | Wholesale & retail | 2017 |
| Celtic Machines Ltd | Manufacturing | 2008 |
| Celtic Roots Farm and Gardens Ltd | Agriculture & fishing | 2022 |
| Celtichr Ltd | Administrative & support | 2013 |
| Centre Stage Dance Festival C.I.C. | Arts & recreation | 2024 |
| CGT Property Services Ltd | Real estate | 2021 |
| Chamberlain Electrical & Technical Services Ltd | Construction | 2015 |
| Charlie Rose Occupational Health Limited | Health & social care | 2015 |
| Chartwell Research Ltd | Professional & scientific | 2026 |
| Chayansc Ltd | Administrative & support | 2023 |
| Cherish Cymru Limited | Health & social care | 2005 |
| Chess Private Wealth Limited | Financial services | 2022 |
| Chesterman Interiors Ltd | Professional & scientific | 2019 |
| Chris Mumford Consultancy Ltd | Professional & scientific | 2009 |
| Christopher Estates Tonteg Limited | Real estate | 2005 |
| Church Bell Properties Ltd | Real estate | 2014 |
| CJC Scenic Services Ltd | Construction | 2018 |
| Cjhd Limited | Wholesale & retail | 2017 |
| Cleaning Supplies Cardiff Limited | Manufacturing | 1971 |
| Clear Construct Limited | Construction | 2012 |
| Clifford Crane Properties Ltd | Real estate | 2019 |
| Clive Edwards Contracts Ltd | Construction | 2013 |
| CM Equestrian Ltd | Wholesale & retail | 2025 |
| CMC Electrics Limited | Construction | 2013 |
| Cmmi Holdings Limited | Financial services | 2021 |
| Co-Hydro Limited | Manufacturing | 2013 |
| Cocoplum Fashion Limited | Wholesale & retail | 2011 |
| Coed Collective Ltd | Arts & recreation | 2025 |
| Coedemlyn Ltd | Other services | 1999 |
| Coedlas Commercial Developments Ltd | Real estate | 2020 |
| Coedlas Holdings Limited | Financial services | 2023 |
| Cogent BUS & Coach Ltd | Wholesale & retail | 2020 |
| Cogent Seating Limited | Manufacturing | 2020 |
| Colada Homes Ltd | Real estate | 2024 |
| Colours of Cowbridge Ltd | Wholesale & retail | 2015 |
| COMPANY717 Ltd | Construction | 2023 |
| Connection Matters Limited | Professional & scientific | 2017 |
| Construction Plant Services Limited | Manufacturing | 2007 |
| Copia QA Limited | Professional & scientific | 2013 |
| Copper Cloud Ltd | Professional & scientific | 2023 |
| Cosy Country Pubs Ltd | Other services | 2019 |
| Court House Freehold Limited | Real estate | 2014 |
| Cowbridge Autos Limited | Wholesale & retail | 2025 |
| Cowbridge Bodyshop Ltd | Wholesale & retail | 2026 |
| Cowbridge Chiropractic Clinic Limited | Health & social care | 2020 |
| Cowbridge Christmas Tree Farm Ltd | Wholesale & retail | 2022 |
| Cowbridge Delicatessen Ltd | Wholesale & retail | 2012 |
| Cowbridge Enterprise Park Limited | Real estate | 2018 |
| Cowbridge Food Festival Limited | Extraterritorial | 2007 |
| Cowbridge Funeral Directors Ltd | Other services | 2021 |
| Cowbridge Mobiles Limited | Manufacturing | 2025 |
| Cowbridge Physic Garden Trust Limited | Arts & recreation | 2004 |
| Cowbridge Trading Co Ltd | Wholesale & retail | 2015 |
| Cowbridge Travel Ltd | Administrative & support | 2021 |
| Cowbridge Tyre Centre Ltd | Wholesale & retail | 2024 |
| Cowbridge Vapes Ltd | Wholesale & retail | 2025 |
| Cozens & Bird Financial Services Ltd | Financial services | 2021 |
| CPB Grambutler Ltd | Other services | 2024 |
| Craigs Cars Care Ltd | Wholesale & retail | 2023 |
| Crarod Ltd | Professional & scientific | 2019 |
| Creativision Media Limited | Information & communication | 2024 |