| DJL Events Ltd | Administrative & support | 2023 |
| DJM Contract Services Ltd | Professional & scientific | 2023 |
| DK Service Global Ltd | Construction | 2019 |
| DKM Enterprise Ltd | Other services | 2019 |
| DKM Property Holdings Ltd | Real estate | 2025 |
| Dljl Farm | Agriculture & fishing | 2024 |
| DM Farms Ltd | Agriculture & fishing | 2014 |
| DMA Stocktaking (2018) Ltd | Information & communication | 2018 |
| DMA Stocktaking (2021) Ltd | Information & communication | 2021 |
| DMA Wealth Management Limited | Professional & scientific | 2018 |
| Dmac Motors Ltd | Wholesale & retail | 2016 |
| DMC Accountants Ltd | Professional & scientific | 2021 |
| DMC Electrical (N.I.) Ltd | Manufacturing | 2020 |
| DMC Modular Design & Build Ltd | Construction | 2020 |
| DMC Motor Factors Limited | Wholesale & retail | 2011 |
| DMC Pizza Ltd | Hospitality | 2020 |
| DMC TAR Ltd | Construction | 2026 |
| Dmcc Retail NI Ltd | Wholesale & retail | 2010 |
| Dmcd Haulage Ltd | Transport & logistics | 2022 |
| Dmcg Holdings Limited | Financial services | 2017 |
| DMG Agri Ltd | Manufacturing | 2017 |
| DMG Auto Repairs Ltd | Other services | 2016 |
| DMG Contracts Ireland Ltd | Construction | 2024 |
| DMK Logistics Limited | Transport & logistics | 2025 |
| DMK Transport Ltd | Transport & logistics | 2023 |
| DO Rightly Productions Ltd | Arts & recreation | 2023 |
| Dobbs Engineering Limited | Professional & scientific | 2024 |
| Doherty Firewood & Fuels Ltd | Wholesale & retail | 2021 |
| Doherty Harvesting Ltd. | Agriculture & fishing | 2006 |
| Dolan Decorating (N.I.) Ltd | Construction | 2021 |
| Dolan Decorating Limited | Construction | 2005 |
| Dolan Retail Ltd | Wholesale & retail | 2013 |
| DON Holdings (NI) Ltd | Real estate | 2013 |
| DON Hotels Limited | Extraterritorial | 2016 |
| Donaghanie Services & Property Ltd | Real estate | 2020 |
| Donaghy Group Ltd | Construction | 2016 |
| Donnell & Ellis Heavy Haulage Limited | Transport & logistics | 2010 |
| Donnelly Bros Contracts Ltd | Construction | 2011 |
| Donnelly Bros. Construction Ltd | Wholesale & retail | 2006 |
| Donnelly Construction Group Ltd | Construction | 2021 |
| Donnelly Investments Ltd | Other services | 2005 |
| Donnelly's Farm Ltd | Wholesale & retail | 2018 |
| Dontein Ltd | Hospitality | 2017 |
| Doogary Garage Services Ltd | Wholesale & retail | 2018 |
| Doogary Renewables Ltd | Energy | 2013 |
| Dooley’S P.I. Limited | Households | 2025 |
| Doughrock Properties Limited | Real estate | 2013 |
| Dowdalls Properties Limited | Financial services | 2020 |
| Doyle Plastering & Concreting Services Ltd | Construction | 2026 |
| DP Motors Tuning Ltd | Wholesale & retail | 2017 |
| DR Rachel Aesthetics Ltd | Other services | 2025 |
| DR37 Ltd | Real estate | 2023 |
| Drafton Farms | Agriculture & fishing | 2026 |
| Dress Connection in Town Limited | Wholesale & retail | 2019 |
| DRJ Farms Limited | Agriculture & fishing | 2002 |
| Dromore 2000 Limited | Administrative & support | 1990 |
| Drum Agri Ltd | Agriculture & fishing | 2019 |
| Drum Properties Ltd | Real estate | 2022 |
| Drumconnelly Developments Ltd | Construction | 2025 |
| Drumduff & Drumnakilly Community Association | Arts & recreation | 2001 |
| Drumeely Construction Ltd | Construction | 2016 |
| Drumeen Ltd | Manufacturing | 2026 |
| Drumhirk Properties Limited | Real estate | 2024 |
| Drumhoney Quality Care Ltd | Health & social care | 2025 |
| Drumlea Poultry Ltd | Agriculture & fishing | 2009 |
| Drumlish Farm Machinery Limited | Manufacturing | 2020 |
| Drumlish Group Ltd | Financial services | 2022 |
| Drumnakilly Supplies Limited | Wholesale & retail | 2005 |
| Drumquin Healthy Living Partnership | Construction | 2019 |
| Drumragh Enterprises Ltd | Construction | 2021 |
| Drumragh Integrated College Ltd | Education | 1995 |
| Drumragh Veterinary Centre Ltd | Professional & scientific | 2018 |
| Drumrusk Farms Ltd | Agriculture & fishing | 2019 |
| Drumwhinny Homes Limited | Construction | 2023 |
| DS Farms Limited | Agriculture & fishing | 2014 |
| DSG2010 | Education | 2011 |
| DTS Farms Ltd | Agriculture & fishing | 2026 |
| DTW Machinery Solutions Limited | Wholesale & retail | 2020 |
| Dublin Road Investments Limited | Financial services | 2025 |
| Dufab Ltd | Manufacturing | 2024 |
| Duff Land Ltd | Hospitality | 2021 |
| Dufmed Limited | Wholesale & retail | 2019 |
| Dullahan Limited | Real estate | 2017 |
| DUN Uladh Limited | Arts & recreation | 1992 |
| Duncan and Griffin Co Limited | Hospitality | 1977 |
| Duncwell Investments Limited | Real estate | 2021 |
| Duncwell Medical Limited | Health & social care | 2024 |
| Dundiven Limited | Construction | 2012 |
| Dunlough Contracts Ltd | Construction | 2020 |
| Dunmoyle Forest Spa Limited | Other services | 2016 |
| Dunmoyle Poultry Limited | Agriculture & fishing | 2017 |
| Dunmullan Lane Management Co Ltd | Households | 2025 |
| Dunnamona Engineering Ltd | Manufacturing | 2013 |
| DVK Forster Limited | Health & social care | 2010 |
| Dynamic Effects Ltd | Information & communication | 2025 |
| Dynamic Equipment Limited | Professional & scientific | 2019 |
| E & D Drywall Ltd | Construction | 2012 |
| E & S Contracts Ltd | Construction | 2026 |
| E Boyle Engineering Ltd | Manufacturing | 2013 |
| EAB Joinery Ltd | Construction | 2023 |