| Dino Healthcare Services Ltd | Health & social care | 2019 |
| Dinosaur Expeditions C.I.C. | Administrative & support | 2013 |
| Direct Disposals Limited | Administrative & support | 2009 |
| Dirty Blonde Brewing Limited | Wholesale & retail | 2023 |
| Dirty Candy Limited | Hospitality | 2016 |
| Dirty Carrot Records Ltd | Information & communication | 2020 |
| Discontinued Designs Limited | Wholesale & retail | 2003 |
| Discover More Travel Ltd | Administrative & support | 2025 |
| Discover Snacks Ltd | Wholesale & retail | 2026 |
| Diskstore Ltd | Wholesale & retail | 2023 |
| Disrupt Outdoor Ltd | Professional & scientific | 2016 |
| Distinct IT Limited | Information & communication | 2003 |
| Distinct Joinery Limited | Construction | 2014 |
| Distinct Worktops Ltd | Manufacturing | 2016 |
| Distinction Gardens Limited | Administrative & support | 2006 |
| Distyll Limited | Information & communication | 2026 |
| Divergence Pictures Limited | Administrative & support | 2023 |
| Diverse Commercial Solutions Ltd | Administrative & support | 2006 |
| Diverse Complete Solutions Limited | Households | 2020 |
| Diverse Design Group Ltd | Extraterritorial | 2021 |
| Diverse Integration Limited | Professional & scientific | 2024 |
| Diverse Vinyl Distribution Ltd | Wholesale & retail | 2022 |
| Diverse Vinyl Properties Ltd | Real estate | 2023 |
| Divine Autos Acceleration Ltd | Wholesale & retail | 2024 |
| Divine Curriculum Ltd | Education | 2023 |
| Divine Vitality Group Ltd | Wholesale & retail | 2025 |
| Diyar Barbers Ltd | Other services | 2020 |
| DJ Executive Travel SW Ltd | Transport & logistics | 2026 |
| DJ45 Promotions Ltd | Arts & recreation | 2023 |
| DJC Health & Wellness Limited | Wholesale & retail | 2024 |
| DJD Builders Limited | Construction | 2012 |
| DJE Solutions Ltd | Construction | 2013 |
| DJH Steel Fixing Ltd | Construction | 2020 |
| DJM Control Solutions Ltd | Administrative & support | 2018 |
| DJR Site Services Limited | Construction | 2011 |
| DJS Services (Newport) Ltd | Wholesale & retail | 2021 |
| Djsn Ltd | Hospitality | 2022 |
| DK Properties SPV Ltd | Real estate | 2024 |
| DK Rigging Ltd | Construction | 2023 |
| DKK Exchange Store Ltd | Wholesale & retail | 2021 |
| DKM Associates Limited | Information & communication | 2025 |
| DKW Props&Stunts Ltd | Information & communication | 2025 |
| DL Accounting Services Ltd | Professional & scientific | 2018 |
| DL Cole Ltd | Construction | 2015 |
| DL Fenton Builders Limited | Construction | 2019 |
| DL2 Promotions Ltd | Arts & recreation | 2022 |
| DL3 Promotions Limited | Arts & recreation | 2017 |
| DLA Property Holdings Limited | Real estate | 2024 |
| DLR Bricklaying and Building Ltd | Construction | 2020 |
| DM Distributions Limited | Other services | 1993 |
| DM Kautai Consultancy Limited | Real estate | 2025 |
| Dmaps Limited Company Limited | Administrative & support | 2016 |
| DMF Properties Limited | Real estate | 2020 |
| DMJ Property Ltd | Construction | 2015 |
| DMT Structural Engineering Ltd | Construction | 2017 |
| DNA Payrolls Ltd | Professional & scientific | 2022 |
| DNO Consulting Limited | Professional & scientific | 2003 |
| DNO Engineering Limited | Construction | 2013 |
| Dnoc Limited | Extraterritorial | 2013 |
| DO YOU Believe? Limited | Wholesale & retail | 2008 |
| Dobar Services Limited | Construction | 2014 |
| Dobby 9 Limited | Other services | 2017 |
| Docit Ltd | Manufacturing | 2025 |
| Dockside Services Limited | Administrative & support | 2021 |
| Doctors & Medics Finance Ltd | Administrative & support | 2021 |
| Doctors & Medics Mortgages Ltd | Administrative & support | 2025 |
| Dodnor Park Limited | Real estate | 2007 |
| DOE Healthcare Agency Ltd | Health & social care | 2022 |
| Dog Owners Guide Limited | Administrative & support | 2019 |
| Dog Shot Golf Ltd | Wholesale & retail | 2026 |
| Doggy Daycare Newport Limited | Agriculture & fishing | 2024 |
| Dohme Developments Ltd | Construction | 2024 |
| Doitforbrodie C.I.C. | Health & social care | 2025 |
| Dolby Procuresmart Limited | Professional & scientific | 2007 |
| Dollface Beauty Ltd | Other services | 2026 |
| Dolls Hair Salon Limited | Administrative & support | 2018 |
| Dollsface Medical Aesthetics Ltd | Health & social care | 2023 |
| Dolphin Court (Freshwater) Management Company Limited | Households | 2002 |
| Dolphin Lodge (Freshwater) Management Company Limited | Households | 2003 |
| DOM Jules Consultancy Ltd | Information & communication | 2018 |
| Domi Product Design Ltd | Professional & scientific | 2017 |
| Domina Skin Clinic Ltd | Other services | 2024 |
| Dominion City Church Cardiff Limited | Health & social care | 2025 |
| Dominium Legal Limited | Professional & scientific | 2024 |
| Domux Facilities Management Ltd | Administrative & support | 2014 |
| Donem Property Ltd | Real estate | 2025 |
| Donmickey Auto Ltd | Wholesale & retail | 2025 |
| Doorkey Estate Agents Ltd | Real estate | 2015 |
| Doorstepparcel Ltd | Wholesale & retail | 2023 |
| Doorway Windows Limited | Construction | 2020 |
| Dopamine DEN Ltd | Real estate | 2026 |
| Dorchester Consultants Limited | Financial services | 2004 |
| Dorothy Seed Ltd | Wholesale & retail | 2021 |
| Dosediary Ltd | Professional & scientific | 2025 |
| Double Blue Destiny Ltd. | Construction | 2015 |
| Double Reed Ltd. | Wholesale & retail | 2011 |
| Doug Solutions IW Ltd | Professional & scientific | 2023 |
| Doughliciouspizza Ltd | Hospitality | 2022 |
| Dove Architectural Design Limited | Professional & scientific | 2014 |
| Dove Tail Bespoke Interiors Ltd | Construction | 2020 |