| Ducales Trading NO.17 Limited | Extraterritorial | 2015 |
| Ducales Trading NO.18 Limited | Extraterritorial | 2015 |
| Ducales Trading NO.19 Limited | Extraterritorial | 2015 |
| Ducales Trading NO.20 Limited | Extraterritorial | 2015 |
| Ducales Trading NO.7 Limited | Financial services | 2013 |
| Ducales Trading NO.8 Limited | Financial services | 2013 |
| Ducales Trading NO.9 Limited | Real estate | 2013 |
| Ducky Ducky Ltd | Wholesale & retail | 2023 |
| Ductus Exemplo Ltd | Professional & scientific | 2015 |
| Dudley Builders Limited | Financial services | 1982 |
| Dufferin (N.I.) Limited | Administrative & support | 2017 |
| Dufferin Shipping Limited | Administrative & support | 1966 |
| Duffs Decor Ltd | Construction | 2024 |
| Duffy & Co. (A&T) Ltd | Professional & scientific | 1995 |
| Duffy Rafferty Communications (DRC) Ltd | Professional & scientific | 1987 |
| DUFFY1955 Ltd | Real estate | 2023 |
| Dugan Electrical Services Limited | Construction | 2010 |
| Dugan Figure Limited | Wholesale & retail | 2024 |
| Duggan Construction Limited | Construction | 2001 |
| Dullerton Road Ltd. | Energy | 2012 |
| Dumbworld Ltd | Arts & recreation | 2007 |
| Dumigans Limited | Hospitality | 2014 |
| Dumpgo Ltd | Wholesale & retail | 2025 |
| DUN Contracts Ltd | Construction | 2021 |
| Dunadry Development Company Limited | Hospitality | 1957 |
| Dunbeg Windfarm Limited | Energy | 2010 |
| Dunbrae Management Company Limited | Households | 2002 |
| Duncaide Limited | Administrative & support | 1984 |
| Duncairn Community Partnership Limited | Other services | 2015 |
| Duncairn Trading Ltd | Transport & logistics | 2011 |
| Duncrue Security Distribution Holdings Limited | Financial services | 2021 |
| Dundee Developments Limited | Construction | 2010 |
| Dundee Renovations Limited | Real estate | 2010 |
| Dunder Mcmifflin Ltd | Wholesale & retail | 2017 |
| Dundonald Angling Club Limited | Agriculture & fishing | 1999 |
| Dundonald Blinds Limited | Manufacturing | 2005 |
| Dundonald Diggers Ltd | Administrative & support | 2025 |
| Dundonald Foodbank Limited | Hospitality | 2015 |
| Dundonald Foods Ltd | Hospitality | 2026 |
| Dundonald Nails & Spa Ltd | Other services | 2026 |
| Dundonald Nurseries Limited | Wholesale & retail | 2014 |
| Dundonald Physiotherapy Ltd | Health & social care | 2014 |
| Dundooan Ltd | Real estate | 2012 |
| Dundrum Restaurants Ltd | Hospitality | 2016 |
| Dundrum Takeaways Ltd | Hospitality | 2020 |
| Duneight Mill Property Management Ltd | Households | 2008 |
| Dunes Apartments Management Company Ltd | Households | 2023 |
| Dunlady Court Management Company Limited | Households | 2002 |
| Dunlady House Limited | Health & social care | 2002 |
| Dunleady Properties Limited | Real estate | 1964 |
| Dunleath Apartments Management Company Limited | Households | 2023 |
| Dunleath Fashion Ltd | Wholesale & retail | 2019 |
| Dunlewey Addiction Services Ltd | Health & social care | 1993 |
| Dunloe Ewart (Lanyon Quay) Limited | Real estate | 2000 |
| Dunlop Hegarty Developments Limited | Construction | 2021 |
| Dunlop Homes Group Limited | Real estate | 2017 |
| Dunlop Investment Holdings Unlimited | Professional & scientific | 2024 |
| Dunluce House Management Company Limited | Households | 2008 |
| Dunluce Pharmacy Limited | Wholesale & retail | 1980 |
| Dunluce Properties Limited | Professional & scientific | 2003 |
| Dunluskin Developments LLP | | 2025 |
| Dunluskin Gardens Management Company Limited | Real estate | 2017 |
| Dunmill Limited | Other services | 2011 |
| Dunmisk Properties Limited | Real estate | 2022 |
| Dunmore 2 Wind Farm Ltd | Energy | 2012 |
| Dunmore Management Company Limited | Households | 2003 |
| Dunmore Pharma Ltd | Wholesale & retail | 2016 |
| Dunmore Stays Ltd | Real estate | 2026 |
| Dunmore Wind Farm Ltd | Energy | 2011 |
| Dunmurry Beds Ltd | Wholesale & retail | 2025 |
| Dunmurry Upholstery Limited | Manufacturing | 2016 |
| Dunnes Stores (Bangor) | Wholesale & retail | 1969 |
| Dunraven Advisory Limited | Other services | 2018 |
| Dunsany Developments Limited | Construction | 2005 |
| Dunsfort Trading Limited | Real estate | 2018 |
| Dunway Holdings Limited | Other services | 2025 |
| Duowu Limited | Wholesale & retail | 2023 |
| Duraflex Europe Limited | Water & waste | 2024 |
| Durmus Yaman Ltd | Wholesale & retail | 2025 |
| Dust Detectors Ltd | Administrative & support | 2025 |
| Duster 74 Limited | Professional & scientific | 2021 |
| Duvalmccoy Guiding Services Ltd | Administrative & support | 2024 |
| Duyufo Ltd | Wholesale & retail | 2025 |
| DV Coaching Ltd | Arts & recreation | 2025 |
| Dvision Technology Limited | Wholesale & retail | 2026 |
| Dvmac Engineering Ltd | Professional & scientific | 2017 |
| DW Bookkeeping and Accountancy Services Limited | Professional & scientific | 2021 |
| DW Contracts Ltd | Construction | 2019 |
| Dwbs Construction Ltd | Construction | 2024 |
| Dwbs Sound and Vision Ltd | Wholesale & retail | 2019 |
| DWC Consultant Ltd | Professional & scientific | 2026 |
| DWD Rail & Commercial Limited | Wholesale & retail | 2019 |
| Dwdl Limited | Professional & scientific | 2021 |
| Dwell Life Ltd | Wholesale & retail | 2024 |
| DWF (Northern Ireland) LLP | | 2016 |
| DWJ Modelling Limited | Professional & scientific | 2021 |
| Dwjw Property Ltd | Real estate | 2023 |
| DWM Composites Ltd | Manufacturing | 2015 |
| DWR Glazing Ltd | Construction | 2024 |
| DXP Living Ltd | Professional & scientific | 2025 |