| Designer Flooring Ltd | Construction | 2025 |
| Designer Sofas Direct Limited | Extraterritorial | 2008 |
| Dettica Consulting and Training Limited | Information & communication | 2007 |
| Development Design Partnership Limited | Professional & scientific | 1978 |
| Devfire Entertainment Limited | Arts & recreation | 2009 |
| Devil's Night Ltd | Information & communication | 2019 |
| Dewi Griffiths Distinctive Jewellery Limited | Wholesale & retail | 2014 |
| Dewivsgoliath CYF. | Professional & scientific | 2025 |
| DFL Family Ltd | Financial services | 2025 |
| DG Retail Ltd. | Wholesale & retail | 2011 |
| Dg-Prop Ltd. | Real estate | 2016 |
| DGD Sales Ltd | Professional & scientific | 2017 |
| DGS Transport Ltd | Transport & logistics | 2017 |
| DH 32 Limited | Hospitality | 2021 |
| Diablo Estates Limited | Construction | 2010 |
| Diamond Cat Limited | Financial services | 2021 |
| Diamond Executive Travel Ltd | Transport & logistics | 2020 |
| Diana Furniture Ltd | Manufacturing | 2022 |
| Dicky Donuts Limited | Manufacturing | 2000 |
| Digiquick Limited | Professional & scientific | 2004 |
| Digital Bakery Limited | Information & communication | 2005 |
| Digital Manufacturing Innovation Hub Wales Ltd | Education | 2019 |
| Digitdoc Records Limited | Information & communication | 2008 |
| DIN Bolighjelper Ltd | Administrative & support | 2025 |
| Dinky Donuts Ltd | Hospitality | 2026 |
| Directnet Accounting Limited | Professional & scientific | 2002 |
| Discount 9 Autotech Ltd. | Wholesale & retail | 1998 |
| DISCOUNTWORLD1 Ltd | Wholesale & retail | 2025 |
| Discovery Ssas Limited | Financial services | 2025 |
| Distinctive Bytes Ltd | Information & communication | 2015 |
| Ditto Solutions Limited | Information & communication | 2013 |
| Divine Crafts Ltd | Wholesale & retail | 2020 |
| Dixon-Jones Properties Limited | Real estate | 2019 |
| DJ Design and Engineering Limited | Professional & scientific | 2025 |
| DJ Property Services Ltd | Real estate | 2016 |
| DJ Tunnelling Labour Consultant Ltd | Construction | 2023 |
| DJ13 Project Management Ltd | Construction | 2025 |
| Djkl Business Solutions Ltd | Professional & scientific | 2011 |
| DK Aviation Solutions Ltd | Professional & scientific | 2015 |
| DK IT Digital Marketing Ltd | Information & communication | 2020 |
| Dkwb Limited | Hospitality | 2022 |
| DL Mobile Tyres Ltd | Manufacturing | 2025 |
| Dlcp Limited | Administrative & support | 2019 |
| DLT Training Holdings Limited | Professional & scientific | 2006 |
| DLT Training Limited | Administrative & support | 1992 |
| DME Gym Services Limited | Manufacturing | 2011 |
| DMN Industries Ltd | Real estate | 2014 |
| DNM Transport Limited | Transport & logistics | 2019 |
| DNS Mechanical Engineering Ltd | Construction | 2019 |
| Doha Textile Ltd | Manufacturing | 2020 |
| Dojo Services Limited | Transport & logistics | 2001 |
| Dollcast Developments Limited | Construction | 2017 |
| Dollcast Limited | Manufacturing | 1978 |
| Domain Monitor Limited | Information & communication | 2022 |
| Domestic Dreams Limited | Information & communication | 2024 |
| Domesticlean Cleaning Limited | Administrative & support | 2023 |
| Don's Kitchen Ltd | Hospitality | 2026 |
| DOS Copas Ltd | Information & communication | 2025 |
| Dose of Tech Services Ltd | Information & communication | 2023 |
| Double Trouble Coffee Roasters Ltd | Manufacturing | 2022 |
| Doubles and Trebles (Bridges) Limited | Wholesale & retail | 2002 |
| Doughp Bridgend Ltd | Hospitality | 2026 |
| Doughp Factory Ltd | Manufacturing | 2026 |
| Doughp Holdings Ltd | Financial services | 2026 |
| Doughp Porthcawl Ltd | Hospitality | 2022 |
| Dovey Estates Limited | Real estate | 1974 |
| Dovey Property Trading Limited | Real estate | 2017 |
| DP Landscaping Ltd | Administrative & support | 2025 |
| DP Law Limited | Professional & scientific | 2011 |
| Dp(Pub Life) Ltd | Hospitality | 2025 |
| DPF Cleaning Bridgend Ltd | Wholesale & retail | 2020 |
| Dphomeserve Ltd | Construction | 2022 |
| DR Bethan Lewis Ltd | Health & social care | 2025 |
| DR Homes Ltd | Households | 2025 |
| DR John Gareth Parry Ltd | Health & social care | 2022 |
| DR Lisa TE Limited | Health & social care | 2025 |
| Drag and Drop Bookkeeping Ltd | Professional & scientific | 2025 |
| Drag Speed Ltd | Transport & logistics | 2014 |
| Dragon (TV and Film) Studios Wales Limited | Real estate | 2018 |
| Dragon Bridge Properties Limited | Real estate | 2025 |
| Dragon Bridgend Limited | Hospitality | 2019 |
| Dragon Complex Building Services Ltd | Administrative & support | 2019 |
| Dragon Developments Ltd | Real estate | 2026 |
| Dragon Drainage Ltd | Water & waste | 2021 |
| Dragon Ecology Limited | Professional & scientific | 2025 |
| Dragon Film Transport Ltd | Transport & logistics | 2025 |
| Dragon Floors Ltd | Construction | 2018 |
| Dragon House Bridgend Ltd | Administrative & support | 2009 |
| Dragon Laser (Holdings) Limited | Manufacturing | 2020 |
| Dragon Laser Limited | Manufacturing | 1995 |
| Dragon Movie Studios (Wales) Limited | Real estate | 2018 |
| Dragon Scale Ltd | Professional & scientific | 2024 |
| Dragon Vans Ltd | Wholesale & retail | 2026 |
| Draig & Grind Ltd | Hospitality | 2026 |
| Draig Access CYF | Construction | 2025 |
| Draig Consultancy Ltd | Professional & scientific | 2020 |
| Draigtech AI Limited | Information & communication | 2025 |
| Drainage Response UK Ltd | Wholesale & retail | 2025 |
| Drainforce Holdings Limited | Financial services | 2012 |
| Drainforce Limited | Water & waste | 2009 |