| Cynefin Outdoor Learning Ltd | Education | 2025 |
| Cynefin Place Limited | Agriculture & fishing | 2025 |
| Cynefin. Calon. Celf. Llantwit Major Festival of the Arts CIC | Education | 2021 |
| Cynhyrchiadau Cardinal CYF | Information & communication | 2024 |
| Cynhyrchiadau IWX Productions Ltd | Arts & recreation | 2021 |
| Cynhyrchiadau TWT Productions Limited | Information & communication | 2013 |
| Cynhyrchu Limited | Information & communication | 2024 |
| Cynlais Group Limited | Financial services | 2025 |
| Cynllun Ltd | Professional & scientific | 2025 |
| Cynnal Cymru - Sustain Wales | Professional & scientific | 2002 |
| Cynnes CYF | Construction | 2021 |
| Cynnydd Consulting Ltd | Professional & scientific | 2026 |
| Cynon Stores Limited | Wholesale & retail | 1974 |
| Cynosure Care Limited | Health & social care | 2019 |
| Cynug Ltd | Real estate | 2026 |
| Cypaw Limited | Information & communication | 2017 |
| Cypher Printworks Limited | Extraterritorial | 2021 |
| Cypher Science Limited | Professional & scientific | 1993 |
| Cyprom Construction Ltd. | Construction | 2017 |
| Cyrene and Aura Ltd | Manufacturing | 2025 |
| Cyrus Bargains Ltd | Wholesale & retail | 2016 |
| Cyrus Bidco Limited | Financial services | 2024 |
| Cyrus Commodities Services Ltd | Wholesale & retail | 2023 |
| Cysrkub Mart Ltd | Wholesale & retail | 2025 |
| Cystems Limited | Information & communication | 2009 |
| CYT Plastering Limited | Construction | 2019 |
| Cytech Design Limited | Professional & scientific | 2013 |
| Cytochrome Games Limited | Information & communication | 2023 |
| Cytun: Eglwysi Ynghyd YNG Nghymru / Churches Together in Wales Limited | Other services | 2006 |
| Cyvehx Ltd | Information & communication | 2024 |
| Czechdelicacies Limited | Wholesale & retail | 2025 |
| Czeczko Design Ltd | Professional & scientific | 2016 |
| Czorny Ltd | Wholesale & retail | 2018 |
| CZQ Cyto Limited | Wholesale & retail | 2025 |
| D & C Professional Services Limited | Professional & scientific | 2014 |
| D & C Salon Ltd | Other services | 2018 |
| D & E Evans Limited | Administrative & support | 2016 |
| D & G Fire and Security Limited | Construction | 2017 |
| D & G Office Interiors Ltd. | Wholesale & retail | 1994 |
| D & H Groundworks Ltd | Construction | 2016 |
| D & J Healthcare Ltd | Health & social care | 2018 |
| D & K Group Limited | Hospitality | 2018 |
| D & K Seabourne Construction Limited | Construction | 2004 |
| D & KN Ltd | Hospitality | 2019 |
| D & L Vans Ltd | Transport & logistics | 2019 |
| D & L Windows Doors and Conservatories Ltd | Construction | 2018 |
| D & M Flooring Limited | Construction | 2022 |
| D & P Drycleaning Limited | Other services | 2013 |
| D & R Couriers Ltd | Transport & logistics | 2016 |
| D & S Automotive Ltd. | Wholesale & retail | 2015 |
| D a L Developments Ltd | Construction | 2024 |
| D a Vowles Building Contractor Limited | Construction | 2011 |
| D and W Associates Ltd | Wholesale & retail | 2018 |
| D C Property Developments Ltd | Real estate | 2024 |
| D Care Turkey Ltd | Administrative & support | 2025 |
| D Cordery Construction Ltd | Construction | 2018 |
| D Damidavicius Fisk Limited | Extraterritorial | 2025 |
| D Dila Private Ltd | Hospitality | 2025 |
| D DOC TM Ltd | Other services | 2019 |
| D Evans Electrical Ltd | Construction | 2026 |
| D F Y N Design Services UK Limited | Professional & scientific | 2024 |
| D Franks Holdings Limited | Financial services | 2026 |
| D H Roberts Enterprises Limited | Health & social care | 2022 |
| D Hardy Roofing Ltd | Construction | 2015 |
| D Harron Contracts Ltd | Transport & logistics | 2016 |
| D I Diali Limited | Administrative & support | 2014 |
| D Ivins Roofing Limited | Construction | 2023 |
| D J Bains Restaurants Ltd | Hospitality | 2017 |
| D J Broughton Ltd | Health & social care | 2023 |
| D J Lawton Consulting Ltd | Professional & scientific | 2016 |
| D J O'Reilly Ltd | Health & social care | 2018 |
| D Joel Integrated Services Limited | Other services | 2018 |
| D Jordan Limited | Professional & scientific | 2013 |
| D M Bevan Group Limited | Financial services | 2001 |
| D M C Vehicle Services Limited | Wholesale & retail | 2006 |
| D M Dental Care Limited | Health & social care | 2013 |
| D O'Connor Property Services Ltd | Construction | 2017 |
| D P E Lighting Limited | Information & communication | 2022 |
| D P Windows Limited | Manufacturing | 2013 |
| D Payne Carpentry Ltd | Construction | 2021 |
| D R GUY GAS Service Limited | Construction | 2018 |
| D R Landscape & Construction Ltd | Construction | 2020 |
| D R O Construction Limited | Construction | 2015 |
| D R Stone Consulting Limited | Administrative & support | 2019 |
| D S Lefter Ltd | Construction | 2018 |
| D S Roberts Construction Limited | Construction | 2015 |
| D Sanderson Services Limited | Construction | 2019 |
| D TAN Dental Ltd | Health & social care | 2022 |
| D Taylor European Ltd | Transport & logistics | 2019 |
| D Valli Ltd | Real estate | 2021 |
| D W Props Ltd | Information & communication | 2017 |
| D W Refrigeration Limited | Manufacturing | 2003 |
| D Young Properties Limited | Administrative & support | 2010 |
| D Zidane Ltd | Wholesale & retail | 2025 |
| D&A Partners Ltd | Real estate | 2026 |
| D&B Elite Services Ltd | Other services | 2016 |
| D&C Delivery Limited | Transport & logistics | 2019 |
| D&C Plastering Limited | Construction | 2025 |
| D&C Recruitment Ltd | Transport & logistics | 2017 |
| D&D Catering Ltd | Hospitality | 2024 |