| Creations 3D Limited | Professional & scientific | 2023 |
| Creative Flair Limited | Extraterritorial | 2006 |
| Creative Nails Ltd | Other services | 2015 |
| Creative Resin Systems Limited | Professional & scientific | 2008 |
| Crestmont Property Group & Developments Ltd | Construction | 2026 |
| Crestview Ascend Ltd | Wholesale & retail | 2025 |
| Cribyn DU Farm Ltd | Agriculture & fishing | 2025 |
| Cribyn-Ddu Agriculture Ltd | Agriculture & fishing | 2025 |
| Critical Rail Limited | Construction | 2014 |
| Critter Corner Holdings Ltd | Manufacturing | 2026 |
| Crossbrace Scaffolding Services Ltd | Construction | 2025 |
| Crossbuild Construction Services Ltd | Construction | 2025 |
| Crowblack CYF | Education | 2019 |
| Crown Class Custom Trading Co., Limited | Wholesale & retail | 2025 |
| CRP Coaching Ltd | Arts & recreation | 2025 |
| Crusher Spares Limited | Administrative & support | 2009 |
| Crust and Grill Kebabs Ltd | Hospitality | 2023 |
| Crwban Care and Support Ltd | Health & social care | 2021 |
| Crystal Clear Cars Ltd | Wholesale & retail | 2020 |
| Csac Services UK Limited | Professional & scientific | 2026 |
| CTB Commercial Bodies Ltd | Manufacturing | 2024 |
| CTR Care Training Ltd | Education | 2017 |
| Curbside SB Ltd | Hospitality | 2021 |
| Curneen Davies Limited | Real estate | 2018 |
| Current Electrical Contractors Ltd | Extraterritorial | 2023 |
| Curvo Grande Limited | Wholesale & retail | 2007 |
| CVT Holiday Inspirations Ltd | Administrative & support | 2024 |
| CWC Holdco Limited | Financial services | 2020 |
| CWL IT Ltd | Construction | 2026 |
| CWM Cudd Ltd | Agriculture & fishing | 2025 |
| CWM Gwyrdd CYF | Health & social care | 2021 |
| CWM Welfare Community Sports Club Ltd | Education | 2020 |
| Cwmdare Homes 2 Limited | Health & social care | 2018 |
| Cwrt Brenin (Freehold) Ltd | Other services | 2020 |
| Cwtch Breakfast Limited | Hospitality | 2024 |
| Cwtchcoffee Ltd | Hospitality | 2019 |
| Cyber Automotive Solution Limited | Wholesale & retail | 2010 |
| Cyfarthfa DC Ltd | Health & social care | 2023 |
| Cymru Craft Staging Ltd | Professional & scientific | 2026 |
| Cymru Plant Repairs Limited | Manufacturing | 2015 |
| Cynyrchiadau Alpha Productions Limited | Information & communication | 2014 |
| Cysylltu Hoyw Cyfyngedig/Queer Connect Limited | Information & communication | 2019 |
| D & B Concrete Pumping Ltd | Construction | 2022 |
| D & S Couriers Ltd | Transport & logistics | 2020 |
| D & S Signs Ltd | Other services | 2011 |
| D E & E Design Solutions Limited | Professional & scientific | 2024 |
| D H Jones Racing Limited | Arts & recreation | 2003 |
| D P Cable Holdings Limited | Financial services | 2022 |
| D P Cable Jointing Limited | Construction | 2015 |
| D S Building & Maintenance Services Limited | Construction | 2016 |
| D S Roofing & Light Haulage Limited | | 1986 |
| D&B Auto Centre Ltd | Wholesale & retail | 2019 |
| D&G Coaches Limited | Transport & logistics | 2022 |
| D&J Owen Holdings Limited | Financial services | 2023 |
| D. G. Hill Limited | Construction | 2012 |
| D. Sims & Sons Accident Repair Centre Limited | Wholesale & retail | 2023 |
| D. Williams Transport Ltd | Transport & logistics | 2025 |
| D365 Integration Solutions Ltd | Information & communication | 2016 |
| DA Silva 7 Ltd | Hospitality | 2020 |
| DA Silva Bricks Ltd | Real estate | 2023 |
| Daerwynno Outdoor Centre / Canolfan Gweithgareddau Awyr Agored Daerwynno | Arts & recreation | 2009 |
| Daffodils Tea Room Ltd | Hospitality | 2021 |
| DAI Clem Building Services Ltd | Construction | 2020 |
| Dairy Shop (Pontypridd) Limited(The) | Wholesale & retail | 1958 |
| Dalton Pest Services Ltd | Agriculture & fishing | 2022 |
| Dandelion Therapy Services Limited | Health & social care | 2021 |
| Danevaelo Engineering Ltd. | Professional & scientific | 2018 |
| Daniel Julian Limited | Health & social care | 2022 |
| Dans Campers and Servicing Ltd | Wholesale & retail | 2025 |
| DAR Developments Ltd | Construction | 2026 |
| Darren Wilson PT Ltd | Arts & recreation | 2020 |
| Davall Construction Pontypridd Ltd | Construction | 2024 |
| Dave Cochlin Engineering Ltd | Professional & scientific | 2018 |
| Dave Phelps Accident Repair Centre Ltd | Wholesale & retail | 2010 |
| David Hooper Home Limited | Information & communication | 2026 |
| Davies and Lowry Limited | Health & social care | 2010 |
| Davies Brothers Ynysybwl Limited | Agriculture & fishing | 2013 |
| Davies Doughty Ltd | Professional & scientific | 2018 |
| Davies Homes (Merthyr) Limited | Construction | 2013 |
| Davies Penywal Farm Limited | Agriculture & fishing | 2025 |
| Davies Renewable Energy Limited | Energy | 2020 |
| Davies's Dolphin Swim School Ltd | Arts & recreation | 2022 |
| DAW Plumbing & Heating Ltd | Construction | 2018 |
| DB Refrigeration Limited | Other services | 2006 |
| Dbeere Sun Properties Ltd | Real estate | 2022 |
| Dbeere Yachts Limited | Administrative & support | 2009 |
| DC Agricultural Fabrication Ltd | Agriculture & fishing | 2025 |
| DC Art Ltd | Professional & scientific | 2021 |
| DCS Light Haulage Ltd | Transport & logistics | 2009 |
| DCS Property Services Limited | Real estate | 2019 |
| Ddraig Hospitality Limited | Hospitality | 2026 |
| DE Plastering Services Ltd | Construction | 2026 |
| Dean Moore Transport Ltd | Transport & logistics | 2021 |
| Dean Newman Decorating Ltd | Construction | 2022 |
| Dean's GAS Ltd | Other services | 2009 |
| Deanos Diggers Limited | Construction | 2005 |
| Deao Group Limited | Professional & scientific | 2021 |
| Deao Limited | Wholesale & retail | 2013 |
| Death Charger Ltd | Manufacturing | 2023 |
| DECADE10 Limited | Administrative & support | 2016 |