| Carmarthenshire Developments SPV 1 Ltd | Construction | 2022 |
| Carmarthenshire Water Ltd | Water & waste | 2006 |
| Carmarthenshire Wood Fuels Ltd | Extraterritorial | 2020 |
| Carmencita Ltd | Health & social care | 2018 |
| Carn Nicholas Farm Limited | Agriculture & fishing | 2023 |
| Carnelian Crafts Ltd | Wholesale & retail | 2023 |
| Carnival Catering Limited | Hospitality | 2014 |
| Carnival Catering OPS Limited | Hospitality | 2024 |
| Carnival Group Ltd | Hospitality | 2023 |
| Carnock House (Tenby) Limited | Hospitality | 2003 |
| Carole ANN Rheinhard Ltd | Extraterritorial | 2024 |
| Carosi Properties Limited | Administrative & support | 2015 |
| Carovet Ltd | Wholesale & retail | 2022 |
| Carp Collaborations | Professional & scientific | 2013 |
| Carp Connection Ltd | Extraterritorial | 2014 |
| Carpanini Consulting Limited | Professional & scientific | 2021 |
| Carr & Wright Enterprises Ltd | Hospitality | 2013 |
| Carreg Developments Limited | Construction | 2008 |
| Carreg LAS Limited | Professional & scientific | 2013 |
| Carreglwyd Caravan Park Limited | Hospitality | 1997 |
| Carreras Communications Limited | Information & communication | 1990 |
| Carrickbrack Ltd | Wholesale & retail | 2025 |
| Carrot Cottage Ltd | Other services | 2024 |
| Cars & W Ltd | Wholesale & retail | 2025 |
| Cars UN Limited | Extraterritorial | 2023 |
| Carsmetics Ltd | Wholesale & retail | 2008 |
| Carter & Co Associates Ltd | Construction | 2006 |
| Carter Phillips Limited | Real estate | 2013 |
| Carter's Auto Repair Centre Limited | Wholesale & retail | 2016 |
| Carter's MOT and Auto Repair Centre Limited | Wholesale & retail | 2013 |
| Carterjp Ltd | Transport & logistics | 2023 |
| Cartrefi Abertawe CYF | Construction | 2025 |
| Cartwn Cymru Cyfyngedig | Information & communication | 1988 |
| Carwyn Consulting Limited | Information & communication | 2024 |
| CAS Training Academy UK Ltd | Education | 2019 |
| Casa Luna Property Ltd | Real estate | 2024 |
| Casa Skewen Ltd | Hospitality | 2019 |
| Casey's Cafe Ltd | Hospitality | 2019 |
| Cash and Carry Composites Limited | Wholesale & retail | 2016 |
| Cash Hardware Stores Limited | Wholesale & retail | 2016 |
| Cash Loans 4 U Limited | Financial services | 2011 |
| Cashmere UK Limited | Agriculture & fishing | 1988 |
| Casiph Limited | Real estate | 2019 |
| Caspian Data Limited | Extraterritorial | 2008 |
| Cast Iron Property Solutions Limited | Professional & scientific | 2024 |
| Cast Performance Academy Ltd | Arts & recreation | 2020 |
| Castell Building Services Ltd | Construction | 2021 |
| Castell Civils Ltd | Construction | 2024 |
| Castell Construction Ltd | Construction | 2019 |
| Castell Developments (Social Housing) Ltd | Construction | 2021 |
| Castell Group Ltd | Construction | 2019 |
| Castell Holdings Ltd | Construction | 2021 |
| Castell Land Holdings RCT SPV 1 Ltd | Construction | 2023 |
| Castell Land Holdings Swansea SPV 1 Ltd | Construction | 2023 |
| Castephens Limited | Hospitality | 2018 |
| Castle Cottages, Oxwich Ltd | Hospitality | 2020 |
| Castle Graig Limited | Construction | 2022 |
| Castle Keep Homes Ltd | Households | 2026 |
| Castle Kitchens (Briton Ferry) Limited | Wholesale & retail | 2019 |
| Castle Properties SA3 Limited | Real estate | 2024 |
| Castle Square Convenience Store Ltd | Wholesale & retail | 2023 |
| Castle View Mumbles Ltd | Construction | 2020 |
| Castleton Estates (Swansea) Limited | Real estate | 1982 |
| Caswell Bay Construction Ltd | Real estate | 2015 |
| Caswell Bay Court Company Limited | Households | 2004 |
| Caswell Bay Court Management Company Limited | Households | 1990 |
| Caswell Cars Limited | Wholesale & retail | 2019 |
| Caswell Holdings Ltd | Real estate | 2015 |
| Caswell Interiors Limited | Construction | 2008 |
| Catalin RFL Ltd | Transport & logistics | 2018 |
| Catalina Wine Mixer Ltd | Real estate | 2022 |
| Catalyst Physiotherapy Ltd | Health & social care | 2015 |
| Catapwlt Ltd | Other services | 2021 |
| Catbells Ltd. | Hospitality | 1982 |
| Caterclean Ltd | Wholesale & retail | 2024 |
| Caterclean Supplies Ltd | Wholesale & retail | 2024 |
| Catering Fabrications Limited | Manufacturing | 2017 |
| Caterworld Limited | Construction | 1979 |
| Catref Bach Limited | Real estate | 2021 |
| Catrin Edwards Independent Financial Services Ltd | Financial services | 2021 |
| Cavelo Group Ltd | Professional & scientific | 2026 |
| Cavendish Group Holdings Limited | Administrative & support | 2016 |
| Cavendish RTM Company Limited | Households | 2007 |
| Cavi Care Ltd | Construction | 2023 |
| Caycik Consulting Services Limited | Professional & scientific | 2024 |
| CB Meded Ltd | Education | 2025 |
| CB Media Resources Limited | Administrative & support | 2012 |
| CB3 Consult Limited | Construction | 2011 |
| CBC Analytics Ltd | Information & communication | 2023 |
| CBM Investment Group Ltd | Real estate | 2025 |
| CBT Consulting Ltd | Professional & scientific | 2023 |
| CBT Wales Limited | Education | 2007 |
| CC (Neath) Ltd | Hospitality | 2025 |
| CC OPS Ltd | Hospitality | 2025 |
| Cclb Logistics Ltd | Transport & logistics | 2021 |
| Cctv (Wales) Ltd | Professional & scientific | 2019 |
| Cctv Access Control Ltd | Administrative & support | 2017 |
| CD Electrical Ltd | Construction | 2020 |
| CD Haulage Limited | Transport & logistics | 2020 |
| CD X Holdings Ltd | Financial services | 2025 |