| Decent Invest and Development Limited | Wholesale & retail | 2012 |
| Deceptive Games Ltd | Information & communication | 2016 |
| Declan Ltd | Manufacturing | 2025 |
| Decorite Supplies Limited | Wholesale & retail | 2018 |
| Deena's Wellness Centre Ltd | Health & social care | 2026 |
| DEF Solar Panels Ltd | Energy | 2020 |
| Delda Carbon Co., Ltd | Wholesale & retail | 2013 |
| Delegara Ltd | Information & communication | 2026 |
| Demada Custom Wine Cellars Limited | Manufacturing | 2020 |
| Denhaus Ltd | Wholesale & retail | 2025 |
| Denkou Decorating Ltd | Construction | 2019 |
| Deou Network Ltd | Wholesale & retail | 2025 |
| Derwen Accountancy Limited | Professional & scientific | 2019 |
| Derwen Tooling Limited | Wholesale & retail | 2000 |
| Design Management Partnership Limited | Professional & scientific | 2004 |
| Designbuild Residences Limited | Professional & scientific | 2025 |
| Designerco Ltd | Professional & scientific | 2021 |
| Desk Consultancy Ltd | Construction | 2018 |
| Destiny Care Solutions Ltd | Education | 2020 |
| Detectaids Limited | Other services | 2007 |
| Dethridge Properties Limited | Real estate | 2018 |
| Development Homes Limited | Construction | 2019 |
| Devonalds LLP | | 2012 |
| Dewis Centre for Independent Living | Health & social care | 1996 |
| Dewis Independent Services | Health & social care | 2015 |
| Dewisiadau Ltd | Hospitality | 2018 |
| Dextadent Limited | Health & social care | 2020 |
| Deyi UK Co., Ltd | Wholesale & retail | 2025 |
| DFM Group Limited | Financial services | 2017 |
| DH Griffiths Agricultural Contractor Ltd | Agriculture & fishing | 2020 |
| DHG Civil Engineering & Rail Ltd | Construction | 2013 |
| Dialact Ltd | Professional & scientific | 2015 |
| Diamond Fadez Barber Ltd | Other services | 2020 |
| Diamond House Foods Limited | Hospitality | 2024 |
| Diamond House Shop Ltd | Hospitality | 2026 |
| Diamond Vehicle Repairs Limited | Wholesale & retail | 2023 |
| Dicax Ltd | Arts & recreation | 2019 |
| Digilith Ltd | Manufacturing | 2009 |
| Digital Dolphin Limited | Agriculture & fishing | 2017 |
| Digital Inclusion Limited | Extraterritorial | 2012 |
| Diligent Financial Limited | Financial services | 2020 |
| Diligent Wealth Planning Limited | Financial services | 2015 |
| Dilton Limited | Wholesale & retail | 2003 |
| Dinas Rock Consulting Ltd | Professional & scientific | 2018 |
| Dingkai Ltd | Wholesale & retail | 2026 |
| Display With Pride Limited | Manufacturing | 2016 |
| DJ Ford Construction Limited | Construction | 2014 |
| DJM Sales Ltd | Administrative & support | 2025 |
| DKM Industry Co. Limited | Wholesale & retail | 2006 |
| DL Simplified Ltd | Administrative & support | 2023 |
| DLJ Estates Ltd | Real estate | 2025 |
| DLS FX Investments Ltd | Financial services | 2021 |
| DM Recycling Services Limited | Water & waste | 2006 |
| DMG Ceremonies Ltd | Other services | 2019 |
| Dmhautos Ltd | Wholesale & retail | 2026 |
| DMP Employee Ownership Trustee Limited | Professional & scientific | 2025 |
| Dodhia Smart Limited | Wholesale & retail | 2020 |
| Dollyrosebeauty Ltd. | Other services | 2018 |
| Domesticlean Limited | Administrative & support | 2019 |
| Dongmingl Ltd | Wholesale & retail | 2023 |
| Doores Beauty Limited | Wholesale & retail | 2025 |
| Doughty Trading Limited | Construction | 2017 |
| Dragon House Trading Limited | Hospitality | 2013 |
| Dragon Nest Deals Ltd | Real estate | 2025 |
| Dragon Paints South Wales Ltd | Wholesale & retail | 2021 |
| Dragon Pizza Ltd | Hospitality | 2024 |
| Dragon Plastics Limited | Extraterritorial | 1982 |
| Dragon-Hire Ltd | Administrative & support | 2019 |
| Draig Electrical Ltd | Construction | 2025 |
| Dresstalks Limited | Wholesale & retail | 2023 |
| Drews Cider Company Ltd | Manufacturing | 2019 |
| Driag Residential Projects Ltd | Construction | 2026 |
| Drija Development Ltd | Construction | 2018 |
| DRL Tax Services Ltd | Professional & scientific | 2022 |
| Drone Force Global UK Ltd | Information & communication | 2020 |
| DS Apparel Ltd | Manufacturing | 2024 |
| DSD Bargain Shop Ltd | Wholesale & retail | 2024 |
| DTL Independent Travel Limited | Administrative & support | 2026 |
| Dual Drive Leasing Ltd | Administrative & support | 2024 |
| Dulad Global Trading Ltd | Wholesale & retail | 2025 |
| Duodecim Ltd | Wholesale & retail | 2024 |
| Duosecure Ltd | Administrative & support | 2023 |
| Dwyer & Phillips Limited | Construction | 2021 |
| Dylan Davies Property Limited | Real estate | 2012 |
| E & N Metal and Waste Recycling Limited | Wholesale & retail | 2017 |
| E and E Upholstery Ltd | Other services | 2025 |
| E College Wales Limited | Education | 1995 |
| E G Sweets & Packaging Limited | Hospitality | 2019 |
| E J P Group Holdings Limited | Financial services | 2021 |
| E-Forecourts Ltd | Real estate | 2021 |
| E-Marketsquare Ltd | Wholesale & retail | 2024 |
| E-Rider Trading Co., Ltd | Wholesale & retail | 2024 |
| E.J Logistics Ltd | Professional & scientific | 2025 |
| E101 Limited | Wholesale & retail | 2024 |
| EAR Care South Wales Limited | Health & social care | 2025 |
| Earthflow UK Limited | Construction | 2015 |
| Earths Free Energy Group Limited | Administrative & support | 2025 |
| Ease-Goaled UK Limited | Construction | 2026 |
| East Facility Floor Company Limited | Wholesale & retail | 2012 |
| Easy Beesey Prints Ltd | Wholesale & retail | 2023 |