| D L Evans & SON Limited | Other services | 2000 |
| D&B Jersey Vault Ltd | Wholesale & retail | 2024 |
| D&H George Ltd | Wholesale & retail | 2017 |
| D&S Surveying Ltd | Construction | 2023 |
| D-Day Assassins Film Ltd | Information & communication | 2018 |
| D.A.B.Tuition Ltd | Education | 2023 |
| D.B. Powell Repairs Ltd | Manufacturing | 2019 |
| D.E.Access Limited | Administrative & support | 2023 |
| D.E.S Developments Ltd | Real estate | 2026 |
| D.J Easton Ltd | Hospitality | 2023 |
| D.J.H. Inspections Ltd | Information & communication | 2023 |
| D.P. Body Repairs Ltd | Manufacturing | 2017 |
| D3SIGNS Limited | Administrative & support | 2009 |
| D4 Logistics Ltd | Transport & logistics | 2013 |
| D8 Projects Limited | Real estate | 2022 |
| DA Scaffolding Ltd | Construction | 2021 |
| Daimant Windows Ltd | Construction | 2026 |
| Dalecast Limited | Extraterritorial | 2026 |
| Dalepond Limited | Administrative & support | 2013 |
| Danefray Limited | Extraterritorial | 2025 |
| Danepine Limited | Construction | 2025 |
| Daniel C Jones Carpentry Ltd | Construction | 2026 |
| Daniel Lambert Wines Limited | Wholesale & retail | 2003 |
| Daniel Matthew Estate Agents Ltd | Real estate | 2015 |
| Daniels Smalley Partnership Limited | Administrative & support | 1998 |
| Dansco Utilities Limited | Energy | 2018 |
| Danubius Transport Ltd | Transport & logistics | 2021 |
| Darlow Lloyd (Construction) Limited | Construction | 2008 |
| Darlow Lloyd Holdings Limited | Professional & scientific | 2013 |
| Darlow Lloyd Plant Limited | Administrative & support | 2013 |
| Daron Services Ltd | Wholesale & retail | 2021 |
| Daros Interiors and Property Development Ltd | Construction | 2024 |
| Darren Hatchett Flooring Ltd | Wholesale & retail | 2024 |
| Dash Equestrian Ltd | Wholesale & retail | 2008 |
| DAT Groundworks Ltd | Construction | 2022 |
| Data Freelancer UK Limited | Information & communication | 2025 |
| Databeck Limited | Extraterritorial | 2026 |
| Datafern Limited | Extraterritorial | 2024 |
| Datascalp Ltd | Information & communication | 2024 |
| Daten Phoenix Limited | Information & communication | 2008 |
| Datum Office Technologies Limited | Wholesale & retail | 2019 |
| Davann Limited | Real estate | 2018 |
| Davell Limited | Real estate | 2023 |
| Davem Property Services Ltd | Real estate | 2021 |
| Davem Training Services Limited | Construction | 2010 |
| Davey Travel Limited | Transport & logistics | 2005 |
| Davey Travel South Wales Limited | Transport & logistics | 2021 |
| Daviation Ltd | Manufacturing | 2025 |
| David B Francis Limited | Construction | 2003 |
| David Gregson Limited | Real estate | 2003 |
| David Sedgwick Solicitors Limited | Professional & scientific | 2008 |
| David Wright Accountants Limited | Professional & scientific | 2000 |
| DAVIDBRINE@10570 Ltd | Hospitality | 2023 |
| Davies & Meredith Limited | Wholesale & retail | 1957 |
| Davies Furlong Consulting Ltd | Administrative & support | 2018 |
| Davies Housing Management Ltd | Real estate | 2025 |
| Davies Konkol Consulting Ltd | Professional & scientific | 2026 |
| Davies Logistics Limited | Transport & logistics | 2002 |
| Davies Repair Limited | Wholesale & retail | 2018 |
| Davies Rolph Ltd | Financial services | 2021 |
| Davis Inspection Services Ltd | Professional & scientific | 2017 |
| Davlee Contractors Ltd | Construction | 2024 |
| Davo Products (Bellows) Limited | Real estate | 1975 |
| DB Elite Properties Limited | Real estate | 2023 |
| DB Sport and Scale Limited | Manufacturing | 2014 |
| DBD Plastering and Building Ltd | Construction | 2026 |
| DC AC Properties Limited | Real estate | 2022 |
| DC Carpentry & Building Ltd | Manufacturing | 2024 |
| DC Carpentry & Roofing Limited | Manufacturing | 2025 |
| DC Electrical Services Cardiff Limited | Construction | 2021 |
| DC Waste & House Removal Ltd | Water & waste | 2025 |
| DCD Daniel Ltd | Transport & logistics | 2026 |
| DCJ Installations Ltd | Construction | 2026 |
| DCT Fire & Security Limited | Construction | 2019 |
| Ddraig Development Group Limited | Financial services | 2025 |
| DE Brito Micallef Holdings Ltd | Real estate | 2021 |
| DE Professional Healthcare Services Ltd | Health & social care | 2019 |
| De-Val-Ca Limited | Construction | 2012 |
| Dean Chilcott Ltd | Manufacturing | 2016 |
| Dean Morgans Salon Ltd | Other services | 2018 |
| Deankirk Limited | Extraterritorial | 2025 |
| Deborah Anne Brittain Limited | Extraterritorial | 2024 |
| Decapp Ltd | Information & communication | 2020 |
| DECEMBERVIAN19 Ltd | Public administration | 2023 |
| Declan Peers Site Services Ltd | Construction | 2024 |
| Deedmoss Limited | Extraterritorial | 2026 |
| Deedrise Limited | Extraterritorial | 2026 |
| Deep & Sara Ltd | Wholesale & retail | 2025 |
| Dejw Haulage Contractors Limited | Transport & logistics | 2006 |
| Delivur Limited | Professional & scientific | 2017 |
| Delta Juliet Limited | Transport & logistics | 1999 |
| Demlogs Limited | Administrative & support | 2014 |
| Demon Fitness Ltd | Other services | 2025 |
| Deneshaw Limited | Other services | 2024 |
| Denis Logistics Ltd | Transport & logistics | 2021 |
| Denjop Limited | Professional & scientific | 2018 |
| Denture Design Centre Limited | Health & social care | 2020 |
| Derefell Limited | Extraterritorial | 2026 |
| Derehart Limited | Extraterritorial | 2025 |
| Designed Future Events Ltd | Manufacturing | 2025 |