| D-Signs + Displays Limited | Professional & scientific | 2007 |
| D-Zine Interiors Ltd | Wholesale & retail | 2024 |
| Dairy Warehouse Ltd | Wholesale & retail | 2010 |
| Dalaone Limited | Hospitality | 2015 |
| Daleash Capital Ltd | Real estate | 2024 |
| Dalgety Spillers Foods Limited | | 1995 |
| Daly Developments Ltd | Construction | 2015 |
| Daly Interiors Ltd | Manufacturing | 2024 |
| Daly Mccormick LLP | | 2026 |
| Daly Mechanical Design Limited | Manufacturing | 2016 |
| Daly Medical Associates Ltd | Health & social care | 2022 |
| Daly Poultry Ltd | Agriculture & fishing | 2012 |
| Daly Transport Ltd | Transport & logistics | 2021 |
| Damien Babington & Sons (UK) Limited | Construction | 2023 |
| Damk Ltd | Agriculture & fishing | 2021 |
| DAN Davidson Limited | Wholesale & retail | 2011 |
| Dancakes Ltd | Hospitality | 2016 |
| Dankarto Limited | Construction | 2012 |
| Danktuary Pharmaceutical Ltd | Manufacturing | 2025 |
| Danu Ltd | Administrative & support | 2021 |
| Darbla Ltd | Financial services | 2025 |
| Darex Trading Ltd | Professional & scientific | 2010 |
| Darryl Martin Investments Limited | Other services | 2008 |
| David (AF) Limited | Arts & recreation | 2014 |
| David Blevins Transport Ltd | Transport & logistics | 2018 |
| David Corr Limited | Wholesale & retail | 2025 |
| David Jameson Services Limited | Wholesale & retail | 1986 |
| Davidson Trading Ltd | Transport & logistics | 2022 |
| Dawson Manufacturing & Engineering Ltd | Manufacturing | 2007 |
| DB Contracts Ltd | Construction | 2005 |
| DBS (Dungannon) Ltd | Wholesale & retail | 2016 |
| DC Drones LLP | | 2025 |
| DC Livestock Haulage Ltd | Transport & logistics | 2008 |
| DCT Calibrations Ltd | Wholesale & retail | 2021 |
| Decking (N.I.) Limited | Manufacturing | 2002 |
| Declan Corr Specialist Roofing Ltd | Construction | 2026 |
| Declan Murphy Car Sales NI Ltd | Wholesale & retail | 2023 |
| Decorative Developments Ltd. | Wholesale & retail | 2010 |
| Deli on the Green Restaurants Ltd | Hospitality | 2016 |
| Deluxe Takeaways Limited | Hospitality | 2019 |
| Demac Properties Ltd | Real estate | 2001 |
| Dern Tech Ltd | Manufacturing | 2009 |
| Dernaborey Eggs Ltd | Agriculture & fishing | 2024 |
| Dernagh Property Developments Ltd | Construction | 2021 |
| Dernaseer Engineering Limited | Manufacturing | 1988 |
| Derroghill (NO1) Ltd | Health & social care | 2024 |
| Derryane Transport Limited | Transport & logistics | 2020 |
| Derryclone Limited | Professional & scientific | 2011 |
| Derrycrew Logistics Ltd | Transport & logistics | 2016 |
| Derryfubble Investments Ltd | Real estate | 2021 |
| Derrygally Farms NI Ltd | Agriculture & fishing | 2023 |
| Derryhale Transport Limited | Transport & logistics | 2010 |
| Derryormond Ltd | Professional & scientific | 2024 |
| Derryvale Limited | Construction | 1987 |
| DES Eakin Steel Services Ltd | Construction | 2025 |
| DF & a UK Ltd | Wholesale & retail | 2019 |
| DF Builders Ltd | Construction | 2012 |
| Dfi.Com Ltd | Wholesale & retail | 2016 |
| DG Engineering Truck Accessories Limited | Manufacturing | 2013 |
| DGB Consultancy Ltd | Professional & scientific | 2025 |
| DGN Electrics Ltd | Construction | 2022 |
| DGR Industries Ltd | Professional & scientific | 2016 |
| Diamond Pharmaceutical Group Ltd | Wholesale & retail | 2026 |
| Diana Kvedariene Ltd | Extraterritorial | 2023 |
| Dicksons & Co. (Dungannon) Limited | Real estate | 1919 |
| Digg for Success Ltd | Professional & scientific | 2022 |
| Digg Mama Ltd | Professional & scientific | 2022 |
| Dilly Dillys Property Ltd | Real estate | 2019 |
| Dirragh Kitchens Ltd | Manufacturing | 2021 |
| Dirragh Motors Limited | Wholesale & retail | 2025 |
| Discount Furniture & Appliances (Armagh) Ltd | Wholesale & retail | 2017 |
| Distag QCS (UK) Ltd | Wholesale & retail | 1971 |
| DJ Mcgorman & SON Ltd | Transport & logistics | 2012 |
| DJD Holdings Ireland Ltd | Financial services | 2022 |
| DJD Transport Ltd | Transport & logistics | 2016 |
| Djemba Djemba Unlimited | Professional & scientific | 2022 |
| DKB Retail Ltd | Wholesale & retail | 2019 |
| DL Freedom Ltd | Wholesale & retail | 2019 |
| DM Investments (NI) Limited | Real estate | 2005 |
| Dmac Engineering Limited | Manufacturing | 2004 |
| DMC Race Promotions Limited | Arts & recreation | 2014 |
| DMG Flooring Contracts Ltd | Construction | 2018 |
| DNA Photography Group Limited | Professional & scientific | 2026 |
| Doctor Cara Aesthetics Ltd | Other services | 2020 |
| Dolson Developments Ltd | Construction | 2025 |
| Dominic Rafferty & Co Ltd | Professional & scientific | 2016 |
| Dominicus Limited | Professional & scientific | 2021 |
| Donaghmore Agri Ltd | Wholesale & retail | 2021 |
| Donaghy Engineering Ltd | Manufacturing | 2016 |
| Donaghys Beragh Ltd | Wholesale & retail | 2011 |
| Donann Consultancy Limited | Extraterritorial | 2023 |
| Donnelly & Taggart Limited | Wholesale & retail | 1991 |
| Donnelly Bros Bangor Limited | Wholesale & retail | 2018 |
| Donnelly Bros. Garages (Fermanagh) Limited | Wholesale & retail | 2001 |
| Donnelly Contracting Ltd | Construction | 2026 |
| Donnelly Farms (NI) Ltd | Agriculture & fishing | 2015 |
| Donnelly Finance & Leasing Limited | Wholesale & retail | 2001 |
| Donntek Ltd | Wholesale & retail | 2024 |
| Doran Tax Consulting Limited | Professional & scientific | 2020 |
| DR Errigal Farms Ltd | Agriculture & fishing | 2025 |