| Cropsafe Limited | Agriculture & fishing | 2019 |
| Cross-Channel Bulk Ltd | Transport & logistics | 2025 |
| Crowned (NI) Ltd | Health & social care | 2014 |
| Crozier Group Ltd | Financial services | 2024 |
| Cruidín Films Ltd | Information & communication | 2025 |
| CS Coffee Co MID Ulster Limited | Hospitality | 2025 |
| CS Rentals Limited | Real estate | 2014 |
| CSM Neurocare Ltd | Health & social care | 2020 |
| CSP Property Limited | Construction | 2021 |
| CSR Hospitality Ltd | Hospitality | 2015 |
| Culmagh Properties Limited | Real estate | 2004 |
| Culnady Ltd | Hospitality | 2020 |
| Curiously Resilient Ltd | Health & social care | 2024 |
| Curragh Utility Services Ltd | Construction | 2026 |
| D & B Contracts Ltd | Administrative & support | 2020 |
| D & M Howard (Moneymore) Ltd | Wholesale & retail | 2016 |
| D & P Mcalister Ltd | Real estate | 2025 |
| D and L Sampson Limited | Wholesale & retail | 2025 |
| D I Flooring Limited | Construction | 2012 |
| D Kelly Transport Limited | Transport & logistics | 2015 |
| D Tourish Groundworks & Construction Ltd | Construction | 2025 |
| D Wilson Contracts Ltd | Construction | 2018 |
| D&B Real Estate Ltd | Hospitality | 2023 |
| D.J. Print Ltd | Administrative & support | 2003 |
| D3138 Limited | Financial services | 2026 |
| DA Investors Ltd | Real estate | 2021 |
| DA Supps & SON Ltd | Wholesale & retail | 2022 |
| Daan Engineering Ltd | Manufacturing | 2023 |
| DAF Joinery Ltd | Construction | 2017 |
| Daffodil Drive Company Limited | Financial services | 2026 |
| Dagota Limited | Wholesale & retail | 2025 |
| Daisy Drive Company Limited | Extraterritorial | 2025 |
| DAL Access Ltd | Construction | 2021 |
| Damascus Delight Ltd | Hospitality | 2026 |
| Damask Developments Ltd | Real estate | 2021 |
| Damec Construction Ltd | Construction | 2018 |
| Damec Holdings Ltd | Financial services | 2020 |
| Darcy & Teds Ltd | Manufacturing | 2024 |
| Darren Henderson Electrical Limited | Construction | 2019 |
| David Mckee Ltd | Real estate | 2011 |
| DB Building and Joinery Contracts Limited | Construction | 2022 |
| DBM Control Systems Limited | Manufacturing | 2020 |
| DBS Parking Ltd | Transport & logistics | 2025 |
| Dead Wing Ltd | Arts & recreation | 2015 |
| Deep Housegs Limited | Wholesale & retail | 2025 |
| Deerpark Construction Ltd | Construction | 2022 |
| Deerpark Digital Investment Limited | Information & communication | 2023 |
| Define Talent Group Ltd | Professional & scientific | 2025 |
| Dejala Limited | Construction | 2024 |
| Delicious Bites (N.I.) Limited | Hospitality | 2020 |
| Derrygannard Transport Ltd | Transport & logistics | 2024 |
| Derrygarve Window Systems Ltd | Construction | 2016 |
| Desertmartin Community Developments Ltd | Real estate | 2000 |
| Devine Wealth Management | Financial services | 2010 |
| Devlin & Sons Contracts Limited | Energy | 2017 |
| Devlin Glass Ltd | Extraterritorial | 2009 |
| DFM Contracts Services (NI) Ltd | Administrative & support | 2022 |
| Dfour Contracts Limited | Construction | 2025 |
| Diamond B&T Ltd | Wholesale & retail | 2026 |
| Diamond by Appointment Limited | Manufacturing | 2009 |
| Diamond Cassidy Limited | Health & social care | 2023 |
| Diamond Innovation Limited | Professional & scientific | 2011 |
| Diamond Investments Limited | Real estate | 2023 |
| Diamond Shelf Company Number 5 Limited | Administrative & support | 2021 |
| Diamond Shelf Company Number 8 Limited | Professional & scientific | 2012 |
| Diamond Shelf Company Number 9 Limited | Financial services | 2013 |
| Diamond Shelf Number 25 | Professional & scientific | 2013 |
| Diamond Shelf Number 27 Limited | Extraterritorial | 2013 |
| Diamond Shelf Number 34 Limited | Extraterritorial | 2014 |
| Digiink Design Ltd | Information & communication | 2009 |
| Digisign Solutions Ltd | Manufacturing | 2023 |
| Digital Construction Live Limited | Construction | 2022 |
| Digitaldatasafe Ltd | Information & communication | 2023 |
| Dillon Hygiene Ltd | Health & social care | 2023 |
| District Pest Control Limited | Administrative & support | 2016 |
| Ditty's (Castledawson) Limited | Manufacturing | 1988 |
| Ditty's (Home Bakery) Limited | Manufacturing | 1995 |
| DJJ Bradley Limited | Professional & scientific | 2021 |
| Dlane Construction (N.I.) Limited | Construction | 2011 |
| Dmac Truck & Trailer Repair Ltd | Wholesale & retail | 2021 |
| DMC Car Transport Ltd | Transport & logistics | 2021 |
| Dmcc Groundworks Limited | Construction | 2017 |
| Dmds Investments Ltd | Real estate | 2016 |
| DMR Mechanical Ltd | Construction | 2018 |
| Doon Group Ltd | Financial services | 2024 |
| Double H Properties Limited | Real estate | 1999 |
| Downvale Trading Limited | Hospitality | 2013 |
| DP Donnelly Ltd | Construction | 2023 |
| DP Dungannon Limited | Hospitality | 2015 |
| DPF Solutions Magherafelt Ltd | Professional & scientific | 2024 |
| DPJ Trading Ltd | Wholesale & retail | 2017 |
| DR a O'Neill Ltd | Health & social care | 2022 |
| DR AMY Aesthetics Belfast Limited | Other services | 2023 |
| DR R H Wray Limited | Health & social care | 2014 |
| Drapersfield Hydro Ltd | Energy | 2025 |
| Dreo Investments Limited | Construction | 2024 |
| Drumanee Construction (N.I.) Limited | Construction | 2019 |
| Drumard Contracts Ltd | Construction | 2021 |
| Drumderg Developments Ltd | Wholesale & retail | 2006 |
| Drumenagh Properties Limited | Real estate | 2017 |