| CUT From the Wild Limited | Manufacturing | 1994 |
| Cutting Roomz Ltd | Other services | 2017 |
| CWC Wedding Cars Limited | Other services | 2010 |
| Cwmafan Community Engagement Centre CIC | Real estate | 2016 |
| Cwmavon Car Sales Limited | Wholesale & retail | 2021 |
| Cwtch Property Developments Limited | Real estate | 2018 |
| Cycle CPD Ltd | Health & social care | 2025 |
| Cyflawn Construction Limited | Construction | 2016 |
| Cymbrogi CIC | Agriculture & fishing | 2023 |
| D & F Building Solutions Ltd | Construction | 2023 |
| D & M Davies Limited | Wholesale & retail | 2003 |
| D & S Carehomes Limited | Health & social care | 2014 |
| D a Security & Inspection Ltd | Professional & scientific | 2013 |
| D C Arpon Ltd | Health & social care | 2019 |
| D J Learning Ltd | Education | 2010 |
| D&D 2022 Ltd | Manufacturing | 2022 |
| D&M Wolmark Building Contractors Ltd | Construction | 2017 |
| D.E.L. Consultancy Ltd | Professional & scientific | 2023 |
| D.J. Thomas Coaches Ltd | Transport & logistics | 2003 |
| D.J. Thomas Holdings Ltd | Financial services | 2025 |
| Dachshund Delivery Limited | Transport & logistics | 2025 |
| Dale Fischer Consulting Ltd | Professional & scientific | 2026 |
| Dale Road (Haverfordwest) Ltd | Construction | 2020 |
| Dalton Fish Bar Limited | Hospitality | 2024 |
| Dalton Road Management Limited | Households | 2017 |
| Damian P Service Limited | Professional & scientific | 2017 |
| Danny Peake Enterprises Ltd | Transport & logistics | 2024 |
| Danny West Tiling Limited | Construction | 2016 |
| Dantwyn (Pontarddulais) Ltd | Construction | 2020 |
| Darcy Developments Limited | Real estate | 2020 |
| Datastac Ltd | Information & communication | 2013 |
| David Howells Transport Ltd | Transport & logistics | 2017 |
| David Millard Driver Services Ltd | Transport & logistics | 2020 |
| David Slee Limited | Real estate | 1983 |
| Davies Carpentry & Fire Protection Ltd | Manufacturing | 2023 |
| Davies Print Group Ltd | Manufacturing | 2026 |
| Davies Property Bryn Limited | Construction | 2024 |
| Davies Skips Limited | Administrative & support | 2004 |
| Davies Warlow Limited | Professional & scientific | 2018 |
| Davlyn PTL Ltd | Real estate | 2016 |
| Dawat Diplus Ltd | Hospitality | 2025 |
| Dawoodji Innovations Limited | | 1986 |
| Dayle Hughes Performance Program Ltd | Arts & recreation | 2026 |
| Dazzle Stencils Ltd | Wholesale & retail | 2015 |
| DB Civil Engineering Ltd | Construction | 2022 |
| Dbelec Ltd | Construction | 2024 |
| DC Carpentry & Joinery Limited | Construction | 2012 |
| DC Health Hub Limited | Health & social care | 2025 |
| DCD Assessment Limited | Health & social care | 2026 |
| DCM Training and Consultancy Limited | Education | 2022 |
| DCN Body and Paint Limited | Wholesale & retail | 2022 |
| Ddowning Ltd | Professional & scientific | 2024 |
| Ddraig Consulting Ltd | Professional & scientific | 2020 |
| DE Lange Holdings Limited | Financial services | 2014 |
| Dean & Abbey Ltd | Education | 2016 |
| Dean Heycock Carpentry Limited | Construction | 2003 |
| Decoration and Finishes (Wales) Ltd | Construction | 2012 |
| Deer Technology Ltd | Manufacturing | 2014 |
| DEL REY Takeaway Ltd | Hospitality | 2025 |
| Delujo Limited | Wholesale & retail | 2016 |
| DEM Corporate Holdings Limited | Financial services | 2013 |
| DEM Property Developments Ltd | Construction | 2020 |
| Dentfree (U.K.) Ltd | Wholesale & retail | 2005 |
| Derwen Road (CWM Mawr) Ltd | Construction | 2020 |
| Deshi Spice 2024 Ltd | Hospitality | 2024 |
| Desi Bite Food Ltd | Hospitality | 2024 |
| Design Hungry Ltd | Professional & scientific | 2022 |
| Dewin Properties Limited | Real estate | 2009 |
| DG Consult (Galashiels) Limited | Construction | 2020 |
| DGP Properties Limited | Real estate | 2020 |
| DH Painting Ltd | Construction | 2024 |
| Digital Inclusion Solutions Community Interest Company | Education | 2026 |
| Digzhc Ltd | Public administration | 2025 |
| Dilash Holdings Limited | Other services | 2016 |
| Dion Wright Ltd | Real estate | 2023 |
| Direct GRP Solutions Limited | Manufacturing | 2016 |
| Diverse Manufacturing Ltd | Manufacturing | 2020 |
| Djinni Flavours Ltd | Manufacturing | 2026 |
| Djinni Group Holdings Ltd | Financial services | 2026 |
| Djinni Ltd | Manufacturing | 2024 |
| DJW Electrical Ltd | Construction | 2021 |
| DKM Groundworks Ltd | Construction | 2024 |
| DL Media Consultants Ltd | Information & communication | 2015 |
| DM Lewis Consultancy Ltd | Professional & scientific | 2024 |
| Dmaa Properties Limited | Real estate | 2017 |
| DME Properties Limited | Real estate | 2019 |
| DMN Tumble Fish and Chips Ltd | Hospitality | 2024 |
| Doggie Dearest Ltd | Other services | 2022 |
| DON Levi Ltd | Wholesale & retail | 2023 |
| Door to Dawes Ltd | Transport & logistics | 2025 |
| Double S Group Limited | Financial services | 2024 |
| Double S Invest Limited | Administrative & support | 2024 |
| Dovetail Carpentry and Construction Ltd | Construction | 2020 |
| DPG Contracting Ltd | Administrative & support | 2023 |
| DR N W Davies & Associates Limited | Health & social care | 2010 |
| Dragon Angling Centre Ltd | Wholesale & retail | 2017 |
| Dragon Feast Limited | Hospitality | 2024 |
| Dragon Holm Limited | Professional & scientific | 2017 |
| Dragon Inns (Wales) Ltd | Hospitality | 2012 |
| Drake Services Ltd | Water & waste | 2018 |