| DR. Michael Mcweeney | Health & social care | 2011 |
| DR. Muna Sabah | Health & social care | 2014 |
| DR. Myles Joyce | Health & social care | 2014 |
| DR. Niall Breslin | Health & social care | 2009 |
| DR. Niall Breslin Gastroenterology Ltd | Professional & scientific | 2009 |
| DR. Niamh NI Choileain | Health & social care | 2014 |
| DR. Nikolay Nikolov | Health & social care | 2010 |
| DR. Noelle Cassidy | Health & social care | 2010 |
| DR. Patrick Magovern Limited | Health & social care | 2010 |
| DR. Patrick Nash | Health & social care | 2012 |
| DR. RAY Mcdermott | Health & social care | 2009 |
| DR. Richard Farrell | Health & social care | 2010 |
| DR. Ronan Kavanagh | Health & social care | 2012 |
| DR. Sharon Moss | Health & social care | 2013 |
| DR. Shi's Holistic Limited | Health & social care | 2015 |
| DR. Siobhan Forman | Health & social care | 2012 |
| DR. Thomas Walsh | Health & social care | 2011 |
| DR. TIM O'Flanagan | Health & social care | 2010 |
| Dr.Kevin Hickey | Health & social care | 2009 |
| Dr.Patrick Thornton | Health & social care | 2011 |
| DRA Trailer Hire Limited | Administrative & support | 2011 |
| Dragon Hoardings Limited | Financial services | 2024 |
| Dragon Performance Ltd | Wholesale & retail | 2025 |
| Drainage Design Ltd | Construction | 2024 |
| Drake Music Project (Northern Ireland) | Arts & recreation | 1996 |
| Dream Holiday H0MES (NI) Ltd | Real estate | 2023 |
| Dreamweaver Linens Ltd | Wholesale & retail | 2007 |
| Drifterstyle Ltd | Arts & recreation | 2023 |
| Drilling Supplies Europe Ltd | Wholesale & retail | 2004 |
| Drilling Supplies Ireland Limited | Extraterritorial | 2001 |
| Dromalane Mill Limited | Real estate | 2003 |
| Dromlis Ltd | Real estate | 2026 |
| Dromliskin Court Management Company Ltd | Households | 2018 |
| Dromore Diocesan Educational Trust | Education | 2018 |
| Dromore Property Limited | Construction | 2006 |
| Drum Point Investments Limited | Construction | 2020 |
| Drumalane Developments Limited | Construction | 2015 |
| Drumaran Electrical Ltd | Construction | 2026 |
| Drumbally Farms Limited | Agriculture & fishing | 2024 |
| Drumbally Transport Ltd | Transport & logistics | 2021 |
| Drumbanagher Parish Ltd | Other services | 2012 |
| Drumbroneth Estate Ltd | Extraterritorial | 2011 |
| Drumbroneth Ltd | Real estate | 2021 |
| Drumed Limited | Construction | 2026 |
| Drumglass Livestock Ltd | Wholesale & retail | 2024 |
| Drumgo Management Limited | Real estate | 1983 |
| Drumhill Surfacing Limited | Construction | 2018 |
| Drumill Properties Ltd | Real estate | 2015 |
| Drumiller Quantity Surveying Ltd | Professional & scientific | 2025 |
| Drumlough Estates Limited | Real estate | 2006 |
| Drumlough Livestock Ltd | Agriculture & fishing | 2011 |
| Drumman Meadows Management Company Limited | Households | 2020 |
| Drummond Contracts Ltd | Construction | 2021 |
| Drummond RDK Limited | Real estate | 2025 |
| Drumroy Enterprises Ltd | Wholesale & retail | 2020 |
| Drumroy Holdings Ltd | Real estate | 2021 |
| Drumroy Ltd | Wholesale & retail | 2016 |
| Drumroy Plant Ltd | Wholesale & retail | 2017 |
| DRY Ice Ireland Ltd | Manufacturing | 2019 |
| DS Contracts Limited | Construction | 2025 |
| DSB Property Ltd | Real estate | 2017 |
| DSJ Consultancy Service Ltd | Professional & scientific | 2025 |
| DTE Organics Limited | Wholesale & retail | 2019 |
| DTM Construction Management Limited | Construction | 2019 |
| Duality Earcare Northern Ireland Limited | Health & social care | 2023 |
| Duality Health & Fitness Ltd | Arts & recreation | 2025 |
| Duality Healthcare Ballymena Limited | Health & social care | 2023 |
| Duality Healthcare Belfast Limited | Health & social care | 2023 |
| Duality Healthcare Derry Limited | Health & social care | 2023 |
| Duality Healthcare Limited | Health & social care | 2023 |
| Duality Healthcare Newry Limited | Health & social care | 2017 |
| Duality Healthcare Northern Ireland Limited | Health & social care | 2023 |
| Duality Healthcare Omagh Limited | Health & social care | 2023 |
| Duality Healthcare Portadown Limited | Health & social care | 2023 |
| Dublin Coach Limited | Transport & logistics | 2017 |
| Dublin Road Services Limited | Professional & scientific | 2005 |
| Duffy Accident Repair Centre Limited | Wholesale & retail | 2010 |
| Duffy Coachbuilders Limited | Wholesale & retail | 2006 |
| Duffy Medical | Health & social care | 2010 |
| Duffy Solicitors Ltd | Professional & scientific | 2017 |
| Duffy's Pork and Bacon Limited | Hospitality | 2021 |
| Duke Street Dental Surgery Ltd | Health & social care | 2010 |
| Dunbyrne Holdings Ltd | Financial services | 2024 |
| Dundalk Dairies Ltd | Wholesale & retail | 2019 |
| Dundalk Road Developments Ltd | Construction | 2025 |
| Durham Street Energy Limited | Financial services | 2024 |
| DV Fulfillment Ltd | Wholesale & retail | 2024 |
| Dvnw Ltd | Construction | 2022 |
| DVS Supplies Ltd | Wholesale & retail | 2022 |
| DW Architecture Ltd | Professional & scientific | 2019 |
| DWE Construction Ltd | Construction | 2022 |
| DXF Engineering Ltd | Professional & scientific | 2021 |
| DXF Group Ltd | Manufacturing | 2023 |
| DYE M&A Holding Ltd | Financial services | 2025 |
| Dynamic Health Consultancy Ltd | Wholesale & retail | 2019 |
| Dysert Solutions Ltd | Financial services | 2012 |
| Dyslexia Services Ltd | Health & social care | 2005 |
| Dómak Group Ltd | Professional & scientific | 2024 |
| E & D Parts Ltd | Wholesale & retail | 2018 |
| E ANN Dunn Medical Limited | Health & social care | 2011 |