| Crestdandy Limited | Real estate | 1983 |
| Crichton Industries Ltd | Construction | 2016 |
| Cricket Cookies Ltd | Manufacturing | 2017 |
| Croesgoch Wind Limited | Energy | 2014 |
| Crow Tree Design Ltd. | Extraterritorial | 2021 |
| Crug YR Efydd Management Limited | Households | 2017 |
| Cryptotude Ltd | Other services | 2019 |
| Crystalgrid Ltd | Extraterritorial | 2022 |
| Crystalsphere Ltd | Administrative & support | 2022 |
| Cuckoo Grove Farms Limited | Agriculture & fishing | 2004 |
| Cuckoo Grove Haverfordwest Limited | Agriculture & fishing | 2017 |
| Cuffern Manor Cottages Managment Company Limited | Hospitality | 2012 |
| Curve Development Limited | Professional & scientific | 2002 |
| CVP Contracting Ltd | Transport & logistics | 2015 |
| CWM Services Ltd | Professional & scientific | 2023 |
| Cwmwdig Management Company Limited | Households | 2008 |
| Cwtch Haus Design Ltd | Wholesale & retail | 2018 |
| Cyder Barn Investments Ltd | Financial services | 2025 |
| Cyder Barn Property Ltd | Real estate | 2025 |
| Cydradd CYF | Professional & scientific | 2026 |
| Cyffin Barn Management Company Limited | Households | 2015 |
| Cymru Quarry Group Limited | Mining & quarrying | 2001 |
| D & P Plant Hire Ltd | Administrative & support | 2019 |
| D a Phillips & SON Limited | Wholesale & retail | 2019 |
| D G Electrical (South Wales) Limited | Construction | 2017 |
| D Reynolds Services Ltd | Financial services | 2021 |
| D T Contractors Limited | Construction | 2024 |
| D&Oconstructionpembs Limited | Construction | 2012 |
| D. & S. Mcnally Limited. | Wholesale & retail | 1985 |
| D.C Marine Ltd | Information & communication | 2019 |
| Dagio Trans Ltd | Other services | 2021 |
| Dairy Farm Managers Ltd | Agriculture & fishing | 2017 |
| Dairycare Limited | Manufacturing | 2005 |
| Dalziel Construction Limited | Construction | 2017 |
| DAN Jones Ltd | Information & communication | 2013 |
| DAN Thomas Engineering Limited | Professional & scientific | 2023 |
| Daria Ltd | Other services | 2021 |
| Darjen Property Ltd | Construction | 2024 |
| Darren Watts Ltd | Professional & scientific | 2024 |
| Dartford Property Investments Limited | Households | 2012 |
| David IAN Kerry Lloyd Dakin Ltd | Extraterritorial | 2022 |
| David Tress | Arts & recreation | 2009 |
| Davies Dwellings Ltd | Real estate | 2023 |
| Davies Richards Design Limited | Professional & scientific | 2007 |
| Daxar Limited | Professional & scientific | 2005 |
| Day’S Best Buy DIY Ltd | Wholesale & retail | 2022 |
| DBC Trading Limited | Hospitality | 2017 |
| Dead Sea Collective Ltd | Wholesale & retail | 2025 |
| Decorating Technician Limited | Construction | 2015 |
| Deedosh Ltd. | Extraterritorial | 2025 |
| Delme Harries Limited | Professional & scientific | 2019 |
| Demimm Ltd | Other services | 2019 |
| Denham-Kennedy Ltd | Construction | 2013 |
| DEW Street Dental Practice Limited | Health & social care | 2011 |
| Dexmonter Trading Ltd | Wholesale & retail | 2023 |
| DF Damp Consultancy LLP | | 2024 |
| DH & CK Morgan Limited | Agriculture & fishing | 2002 |
| Diando Ltd | Wholesale & retail | 2019 |
| Dianne Enterprises Ltd | Hospitality | 2024 |
| Diexo Ltd | Other services | 2019 |
| Digitex International LP | | 2018 |
| Digitory Group PC | | 2019 |
| Dirty West Ltd | Information & communication | 2025 |
| Discipling Nations to Christ Ministries Limited | Extraterritorial | 2017 |
| Divinita Health Ltd | Extraterritorial | 2025 |
| Dkan Groundworks Limited | Construction | 2013 |
| DNU Properties Limited | Real estate | 2024 |
| Dolize Ltd | Other services | 2019 |
| DOMIK21 Ltd | Extraterritorial | 2023 |
| Dooel Ltd | Other services | 2022 |
| Doppel:Punkt Ltd | Extraterritorial | 2021 |
| Dower Property Limited | Real estate | 2022 |
| Dpsb Leisure Limited | Hospitality | 2024 |
| DR Beynon's BUG Farm Limited | Agriculture & fishing | 2013 |
| DR D.A. Cooke Limited | Health & social care | 2003 |
| DR Kal's Skin Clinic Ltd | Health & social care | 2024 |
| DR Laurence Glyn Williams Limited | Agriculture & fishing | 2015 |
| Dragon Cleaning Solva Ltd | Administrative & support | 2021 |
| Dragon Cleaning St.Davids Ltd | Administrative & support | 2021 |
| Dragon Scaffolding Services Ltd | Construction | 2026 |
| Dragon Wifi Limited | Information & communication | 2014 |
| Dragon Ystadau Ltd | Real estate | 2021 |
| Drapil Ltd | Other services | 2021 |
| Dreen Hill Motors Ltd | Wholesale & retail | 2011 |
| Dress for the Occasions Limited | Other services | 2011 |
| DRH Support Services Limited | Administrative & support | 2016 |
| Drifter Tyddewi Ltd | Hospitality | 2025 |
| Drive Connect Ltd | Wholesale & retail | 2024 |
| Driving Pleasure International Ltd | Administrative & support | 2025 |
| Dsjs Services Ltd | Administrative & support | 2025 |
| DU Healing Point Ltd. | Extraterritorial | 2023 |
| Duckspool Limited | Agriculture & fishing | 2017 |
| Dunlop Motors Ltd | Wholesale & retail | 2023 |
| Duomo Building Services Limited | Construction | 2024 |
| Dyfed Eco Solutions Ltd | Administrative & support | 2024 |
| Dynamia Ltd | Other services | 2019 |
| Dynamite Competitions Ltd | Arts & recreation | 2024 |
| Dynosonic Ltd | Professional & scientific | 2013 |
| E&R Tree & Landscapes Ltd | Construction | 2024 |
| E. J. Luke Limited | Real estate | 2020 |