| DMV QA Limited | Financial services | 2013 |
| DMV QCA Limited | Financial services | 2022 |
| DN Freelancing Ltd | Wholesale & retail | 2026 |
| DN Nankani Care Ltd | Health & social care | 2024 |
| DNA Acquisitions Ltd | Real estate | 2023 |
| DNA Definitive Limited | Professional & scientific | 2012 |
| DNA Enterprises Limited | Information & communication | 1994 |
| DNA IEP Ltd | Professional & scientific | 2022 |
| DNA Property Development Southwales Limited | Real estate | 2026 |
| DNA Tracer Technologies Ltd | Professional & scientific | 2011 |
| Dnaled Services Limited | Manufacturing | 2019 |
| DNC Bar Ltd | Hospitality | 2026 |
| DNC Carpentry&Fit Outs Limited | Construction | 2014 |
| DND Trading School Ltd | Education | 2024 |
| Dndt+ Limited | Information & communication | 2025 |
| DNM Investment Ltd | Professional & scientific | 2012 |
| DNM Services Limited | Other services | 2018 |
| Dnsync Ltd | Wholesale & retail | 2025 |
| Dntn Property Consultancy Limited | Wholesale & retail | 2021 |
| DNW Automotive Ltd | Wholesale & retail | 2019 |
| DNW Property Limited | Real estate | 2019 |
| DO Century Garments Ltd | Manufacturing | 2019 |
| DO OR DIE Records Limited | Arts & recreation | 2011 |
| DO RE MI Canu CYF | Arts & recreation | 2025 |
| Dobacon Ltd | Wholesale & retail | 2025 |
| Doblay Cardiff Limited | Hospitality | 2013 |
| Doblay Ltd | Professional & scientific | 2013 |
| Dobson & Barlow Limited | | 1931 |
| Dochify Ltd | Wholesale & retail | 2025 |
| Dock Speed UK Ltd | Transport & logistics | 2026 |
| Dockham Mechanical Limited | Construction | 2017 |
| Dockland Services Ltd | Other services | 2015 |
| Dockrat Industries Ltd | Manufacturing | 2014 |
| Dockwhite Ltd | Information & communication | 2025 |
| Docplus Technology Limited | Health & social care | 2025 |
| Doctor King Technology Co. Ltd. | Manufacturing | 2021 |
| Doctor Mediex UK Ltd. | Wholesale & retail | 2017 |
| Doctorem Global International Ltd | Wholesale & retail | 2024 |
| Doctum Ltd | Information & communication | 2025 |
| Docublock Ltd | Information & communication | 2025 |
| Document Continuity & Capture Limited | Administrative & support | 2004 |
| Dodaj Constructco Ltd | Construction | 2024 |
| Doddwood Limited | Health & social care | 2013 |
| Dodo Global Information Technology Consultancy Activities Limited | Information & communication | 2025 |
| Dodproducts Ltd | Wholesale & retail | 2025 |
| Dodyexpress Ltd | Wholesale & retail | 2025 |
| DOE Properties Limited | Real estate | 2020 |
| Doeth Ltd | Real estate | 2017 |
| Dofednod CYF | Agriculture & fishing | 2014 |
| Dofestory Diamond&Coffee Co., Ltd. | Wholesale & retail | 2019 |
| Dofusoul Limited | Wholesale & retail | 2025 |
| Dog & GUN Bearpark Ltd | Hospitality | 2019 |
| Dogan Kurbani Ltd | Wholesale & retail | 2025 |
| Doge Marine Ltd | Extraterritorial | 2025 |
| Dogespace Ltd | Information & communication | 2021 |
| Doggie Day Camp Ltd | Other services | 2017 |
| Doggy Day Care Limited | Other services | 2019 |
| Dogo Capital Ltd | Wholesale & retail | 2019 |
| Doherty Property & Development Ltd | Real estate | 2019 |
| Dohira Ltd | Wholesale & retail | 2025 |
| Doho Ventures Ltd | Professional & scientific | 2022 |
| Doidge Watches Ltd | Manufacturing | 2023 |
| Doitnow Research Limited | Information & communication | 2021 |
| Dojosz Limited | Construction | 2025 |
| Doku Network Solutions Ltd | Manufacturing | 2018 |
| Dolan Court Residents Company Limited | Households | 2000 |
| Dolce Vittore Limited | Wholesale & retail | 2024 |
| Dolen Cymru - Wales Lesotho Link | Other services | 2011 |
| Dolera Services Ltd | Administrative & support | 2021 |
| Dolerite Ltd | Professional & scientific | 2017 |
| Doll Aesthetics Leicester Ltd | Other services | 2025 |
| DOLL4R Limited | Wholesale & retail | 2021 |
| Dollmen Ltd | Wholesale & retail | 2026 |
| Dolly & Dimples Hair and Beauty Ltd | Other services | 2019 |
| Dolly Holdings Limited | Hospitality | 2025 |
| Dolly Pattern Ltd | Wholesale & retail | 2016 |
| Doloob Limited | Wholesale & retail | 2021 |
| Dolphcart Ltd | Wholesale & retail | 2026 |
| Dolphin Care Agency Limited | Health & social care | 2001 |
| Dolphin Health & Hygiene Ltd | Wholesale & retail | 2026 |
| Dolphin Way Trading International Ltd | Wholesale & retail | 2022 |
| Dolte Enterprises Limited | Information & communication | 2017 |
| Dolyffin Ltd | Information & communication | 2026 |
| DOM Vsem Limited | Administrative & support | 2016 |
| Domalix Ltd | Wholesale & retail | 2025 |
| Domani Private Digital Ltd | Information & communication | 2018 |
| Domcom Investments Ltd | Real estate | 2025 |
| Dome Kitchen Ltd | Hospitality | 2018 |
| Domeniks Ltd | Other services | 2019 |
| DOMEROCK1 Limited | Real estate | 2024 |
| Domestic Care Experts Ltd | Other services | 2025 |
| Domestic Divas Limited | Administrative & support | 2004 |
| Domestic Goods Cover Ltd | Other services | 2019 |
| Domesticon Ltd | Construction | 2025 |
| Domicilio Ltd | Households | 2021 |
| Domimex Construction Ltd | Construction | 2018 |
| Dominic Homes Ltd | Construction | 2016 |
| Dominion Garage Ltd | Wholesale & retail | 2020 |
| Dominion Inc Ltd | Information & communication | 2017 |
| Dominion Learning Centre Cardiff Ltd | Education | 2023 |