| Doire Dress Ltd | Manufacturing | 2016 |
| DOK Couriers Ltd | Transport & logistics | 2025 |
| DOK Estates Ltd | Real estate | 2024 |
| Dominic Singh Hans Limited | Professional & scientific | 2023 |
| Domo Home Ltd | Wholesale & retail | 2020 |
| Domus Grata Ltd | Hospitality | 2024 |
| DON Laughlin & Company Ltd | Professional & scientific | 2010 |
| Donaghy Joinery Limited | Construction | 2020 |
| Donaghy's Takeaway Limited | Hospitality | 2022 |
| Donark Modular Limited | Manufacturing | 2025 |
| Donegal Competitions Ltd | Wholesale & retail | 2026 |
| Donegal Seaweed Limited | Manufacturing | 2025 |
| Donnelly Hire LLP | | 2006 |
| Donnybrewer Developments Limited | Real estate | 2001 |
| Doonwood Limited | Hospitality | 2022 |
| Dopey Dick Brewing Ltd | Manufacturing | 2019 |
| Dorby Leisure Ltd | Hospitality | 2023 |
| Dorset Projects Ltd | Real estate | 2018 |
| DOS Amigos Properties Limited | Real estate | 2026 |
| Double Jump Studios Ltd | Professional & scientific | 2015 |
| Doyen Pictures Ltd | Information & communication | 2019 |
| DPF Vmed Networks Limited | Professional & scientific | 2017 |
| DPG Mechanical Services Ltd | Manufacturing | 2025 |
| DPK Retail Ltd | Wholesale & retail | 2013 |
| Dpps Contracts UK Limited | Construction | 2014 |
| DPT Group Holdings Ltd | Manufacturing | 2018 |
| DR a Aesthetics @ Victoria Gate Limited | Health & social care | 2022 |
| DR Forklift Ltd | Wholesale & retail | 2023 |
| DR. CMG Aesthetics Limited | Health & social care | 2023 |
| Dragon Counter Chen Limited | Hospitality | 2022 |
| Dream Big Group UK Ltd | Arts & recreation | 2025 |
| Drive 105 FM Community Radio Ltd | Information & communication | 2010 |
| Drls (N.I) Ltd | Construction | 2020 |
| Drukes Ltd | Financial services | 2024 |
| Drumadooey Concrete (N.I.) Limited | Mining & quarrying | 2023 |
| Drumboarty Holdings Limited | Financial services | 2025 |
| Drumcliff Electrical Consultants Ltd | Professional & scientific | 2017 |
| Drumfries Ltd | Manufacturing | 2025 |
| Drummond Manor Residents Limited | Extraterritorial | 2009 |
| Dryas Phyto Ltd | Agriculture & fishing | 2023 |
| DSB Fit OUT Limited | Construction | 2021 |
| Dtac Consultancy Limited | Information & communication | 2025 |
| DTS Entertainments Ltd | Administrative & support | 2025 |
| Duddy Holdco Limited | Hospitality | 2023 |
| Duddy Superholdco Limited | Hospitality | 2023 |
| Duey Bros (N.I.) Ltd | Administrative & support | 2023 |
| Duffy Bros Construction NI Limited | Construction | 2021 |
| Duffy Surveying Limited | Professional & scientific | 2015 |
| Duhube Associates Limited | Administrative & support | 2018 |
| Dumpngsove Ltd | Wholesale & retail | 2026 |
| Dunbar Limited | Real estate | 1995 |
| Duncreggan Scaffolding Services Ltd | Construction | 2023 |
| Duncreggan Student Village Limited | Households | 2001 |
| Dunelm (Soft Furnishings) Londonderry Ltd | Administrative & support | 2021 |
| Dunlade Limited | Professional & scientific | 1993 |
| Dunluce Family Centre Limited | Education | 2002 |
| Dunmore Investments Limited | Real estate | 2014 |
| Dunrobin Holdings Limited | Financial services | 2025 |
| Dunvale Consulting Ltd | Professional & scientific | 2018 |
| Duquesa Estates Ltd | Real estate | 2019 |
| Durotec Ltd | Administrative & support | 2020 |
| DVH Property Holdings Limited | Financial services | 2026 |
| DWI (NI) Limited | Energy | 2013 |
| Dynamic Sales Force Ltd | Professional & scientific | 2019 |
| Dynasty Foods Limited | Wholesale & retail | 2024 |
| E C Cross Limited | Hospitality | 2023 |
| E Global Deals Ltd | Wholesale & retail | 2024 |
| E M Investments Limited | Real estate | 2017 |
| E&I Jointing Ltd | Manufacturing | 2020 |
| E.D Fit-Outs Ltd | Construction | 2017 |
| E.Mcc Contracts Ltd | Construction | 2025 |
| E.R.M. Mechanical Services Limited | Construction | 1994 |
| Eagry Consulting Limited | Information & communication | 2023 |
| Earl's Gate Management Co Ltd | Extraterritorial | 2005 |
| Earlsfort Projects Ltd | Real estate | 2022 |
| Earthtract Commercial Limited | Manufacturing | 2019 |
| Eastbrook Distributions (NI) Limited | Wholesale & retail | 2020 |
| Easy Apartments Limited | Real estate | 2019 |
| Easy Lets N.I. Ltd | Real estate | 2010 |
| EAW Properties Ltd | Real estate | 2024 |
| Ebrington (NI) Ltd | Wholesale & retail | 2010 |
| Ebrington Hotel Limited | Extraterritorial | 2022 |
| Ebrington Property Limited | Hospitality | 2024 |
| EC DC Electrical Ltd | Construction | 2023 |
| ECA Cladding Consultants Ltd | Construction | 2022 |
| Ecac Property Group Ltd | Real estate | 2026 |
| ECB Timber Supplies Ltd | Wholesale & retail | 2015 |
| Ecca Properties Ltd | Real estate | 2024 |
| Echo Echo Dance Theatre Company | Arts & recreation | 1998 |
| Ecobur Ltd | Professional & scientific | 2025 |
| Ecocooling Refrigeration & Air Conditioning Services Ltd | Manufacturing | 2022 |
| Ecomms Digital EU Ltd | Information & communication | 2021 |
| ECR Healthcare Limited | Health & social care | 2021 |
| ED Promotions Ltd | Hospitality | 2023 |
| Eden Aesthetic Clinic Ltd | Health & social care | 2026 |
| Edendale Properties Ltd | Real estate | 2020 |
| Edenreagh Developments Limited | Construction | 1986 |
| Edge Leadership Ltd | Professional & scientific | 2021 |
| Edible Installs Ltd | Professional & scientific | 2022 |
| Educate 3D Printing Ltd | Manufacturing | 2020 |