| Davies & Jones Builders Ltd | Construction | 2015 |
| Davies & Jones Holdings Limited | Financial services | 2022 |
| Davies Jewellers Limited | Wholesale & retail | 1999 |
| Davington Properties Limited | Real estate | 2009 |
| Davy's Bikes Limited | Wholesale & retail | 2017 |
| Dawn Consulting Limited | Professional & scientific | 2026 |
| DB Sound Ltd | Information & communication | 2015 |
| Dbrm Ltd | Agriculture & fishing | 2016 |
| DC Wealth Ltd | Financial services | 2023 |
| DDJ Belfast Ltd | Hospitality | 2024 |
| DDS Trader Ltd | Wholesale & retail | 2023 |
| Deafinterpretersni Ltd | Professional & scientific | 2025 |
| Dean Mcclenaghan Ltd | Construction | 2024 |
| Deburca Limited | Professional & scientific | 2025 |
| Decj Property Rental & Maintenance Ltd | Construction | 2012 |
| DEE5 Ltd | Professional & scientific | 2023 |
| Deiniol Developments Limited | Construction | 2002 |
| Dejavoo Bangor Ltd | Wholesale & retail | 2025 |
| Dejavu Bangor Limited | Wholesale & retail | 2023 |
| Dejavu Shop Limited | Wholesale & retail | 2025 |
| Delicate INK Ltd | Other services | 2023 |
| Demed Holdings Limited | Financial services | 2015 |
| Den-Solutions Limited | Health & social care | 2018 |
| Denefield Limited | Professional & scientific | 2005 |
| Denis D Humphrey LLB Limited | Professional & scientific | 2026 |
| Denis Ferranti Group Limited | Financial services | 2021 |
| Denis Ferranti Meters Limited | Manufacturing | 1927 |
| Denis Ferranti-Hoverknights Limited | Transport & logistics | 1970 |
| Denise Mccluskey Ltd | Manufacturing | 2022 |
| Denmil Consulting Ltd | Professional & scientific | 2009 |
| Denroy Group Holdings Limited | Financial services | 2015 |
| Dentistry by Mike Limited | Real estate | 2021 |
| Dermco Holdings Ltd | Health & social care | 2023 |
| Dermco Ltd | Health & social care | 2023 |
| Derryvolgie Mews Management Company Limited | Real estate | 1999 |
| Derw Coffee Ltd | Manufacturing | 2020 |
| Desi Food Point Ltd | Hospitality | 2024 |
| Design Ethos Limited | Other services | 2004 |
| Design to Scale Limited | Information & communication | 2020 |
| Designer Homeworks Ltd | Wholesale & retail | 2018 |
| Dfjg (Scott) Properties Limited | Real estate | 2019 |
| Dhea Properties Limited | Extraterritorial | 2022 |
| Diamond DJ Beautiful Noise Limited | Arts & recreation | 2024 |
| Diamond Mortgage Advice Ltd | Financial services | 2025 |
| Diamond Nails and Spa Bangor Ltd | Other services | 2022 |
| Digiroom Ltd | Information & communication | 2022 |
| Digital Express Solution Limited | Wholesale & retail | 2025 |
| Digitalbio Systems Ltd | Professional & scientific | 2024 |
| Digwyddiadau Sbarc CIC | Professional & scientific | 2018 |
| Dilwyn's Coaches Ltd | Transport & logistics | 2018 |
| Dilyn Natur Guided by Nature CIC | Health & social care | 2023 |
| Dining Oriental Ltd | Hospitality | 2017 |
| Dioko Housing Limited | Real estate | 2025 |
| Direct Deal Limited | Construction | 2000 |
| Divine Hope Care and Support Limited | Administrative & support | 2025 |
| DJF Holdings Limited | Real estate | 2024 |
| DK Electrical Solutions Ltd | Construction | 2026 |
| DKS Group Ltd | Wholesale & retail | 2025 |
| DKY Hair Company Limited | Other services | 2015 |
| DKY Properties Limited | Other services | 2013 |
| DL Contracts (NI) Limited | Administrative & support | 2013 |
| DLK DO IT Your Way Ltd | Wholesale & retail | 2024 |
| DM Design & Build Limited | Construction | 2026 |
| DM Supplies (NI) Limited | Wholesale & retail | 2013 |
| Dmacc Limited | Professional & scientific | 2022 |
| DMB Consulting Ltd | Information & communication | 2016 |
| DMC Consulting Ltd | Information & communication | 2026 |
| DNA Group Limited | Wholesale & retail | 2018 |
| DNM T/A Homme Ltd | Wholesale & retail | 2019 |
| Doast Ltd | Hospitality | 2026 |
| Dobhamcq Limited | Hospitality | 2024 |
| DOK Property Limited | Real estate | 2021 |
| Dolen Cyfyngedig | Administrative & support | 2016 |
| Domestic & Commercial Drain Services Ltd | Water & waste | 2005 |
| Donard Apartments Limited | Extraterritorial | 1979 |
| Donegans Limited | Hospitality | 2017 |
| Donnan & Co Ltd | Professional & scientific | 2024 |
| Doodle Girl UK Ltd | Information & communication | 2023 |
| Doorcraft Design Limited | Manufacturing | 2003 |
| Dormans Court Management Company Limited | Extraterritorial | 1998 |
| Doubleewe Ltd | Information & communication | 2025 |
| Dougan Contracts Ltd | Construction | 2009 |
| Douglas, Fierce and Little Ltd | Real estate | 2017 |
| Douleen Inns Limited | Hospitality | 2001 |
| DR R W Psychology Ltd | Health & social care | 2023 |
| DR Zigs Ltd | Manufacturing | 2014 |
| Dragon Aeronautical Services (GP) Limited | Administrative & support | 2019 |
| Dragon Aeronautical Services LP | | 2019 |
| Dragon Carpets & Upholstery Cleaning Ltd | Administrative & support | 2026 |
| Dragon Vape Ltd | Wholesale & retail | 2026 |
| Draig Group Ltd | Construction | 2026 |
| Drannandow Holding Co Ltd | Agriculture & fishing | 2023 |
| DRB Enterprises NI Ltd | Wholesale & retail | 2024 |
| DRC Utilities Limited | Construction | 2018 |
| Dreigiau'R Dyffryn Ltd | Arts & recreation | 2020 |
| Drilling and Pumping Supplies Limited | Wholesale & retail | 1991 |
| Dru(Uk) | Hospitality | 1988 |
| Drymiol CYF. | Education | 2013 |
| DS Ceilings Limited | Construction | 2016 |
| DU Construction Limited | Construction | 1996 |