| ADJ Construction Limited | Construction | 2011 |
| Adlon Ready MIX Limited | Construction | 2019 |
| Adlon Trading Limited | Real estate | 2016 |
| ADR Freight Ltd | Transport & logistics | 2012 |
| Adrian Markey Ltd | Professional & scientific | 2016 |
| Adrian Mccaul Ltd | Transport & logistics | 2025 |
| Adrian Trainor Contracts Ltd | Construction | 2017 |
| Adrl Professional Ltd | Construction | 2019 |
| Adsky PTE Limited | Wholesale & retail | 2025 |
| Advance Fasteners Limited | Wholesale & retail | 2011 |
| Advance Ireland Ltd | Other services | 2020 |
| Advanced Bookkeeping Services NI Ltd | Professional & scientific | 2025 |
| Advanced Cardiac Diagnostics Ltd | Health & social care | 2026 |
| Advent Wind Energy Limited | Energy | 2014 |
| Advent Wind Ltd | Energy | 2010 |
| Adventure Leadership Training Trust | Administrative & support | 2004 |
| Advocacy VSV | Health & social care | 2018 |
| Aeig Compressed Air Specialists Limited | Professional & scientific | 2025 |
| AER Excel Limited | Other services | 2013 |
| Aereum Ltd | Extraterritorial | 2024 |
| Aethera Clinic Ltd | Health & social care | 2025 |
| AF Consultancy Ireland Ltd | Professional & scientific | 2019 |
| AF Whiskey Services Ltd | Professional & scientific | 2019 |
| AFK Services Limited | Agriculture & fishing | 2019 |
| Afto NI Ltd | Wholesale & retail | 2023 |
| Ag-Con Products Limited | Manufacturing | 2001 |
| Again Technologies (Newry) Limited | Manufacturing | 2021 |
| AGC Utilities Limited | Construction | 2017 |
| Aghincurk Plumbing Ltd | Construction | 2017 |
| Agms Ltd | Administrative & support | 2002 |
| Agri Drones Ireland Limited | Water & waste | 2019 |
| Agri Land (N.I.) Limited | Wholesale & retail | 2019 |
| Agri Plant Windscreens Ltd | Manufacturing | 2017 |
| Agrigear (NI) Limited | Wholesale & retail | 2019 |
| Agrihand Contracts Ltd | Agriculture & fishing | 2025 |
| Agritech-Ni Ltd | Wholesale & retail | 2022 |
| Agtbmj Trading Ltd | Financial services | 2016 |
| AH Aesthetics & Skincare Ltd | Health & social care | 2024 |
| AH Bricklaying Ltd | Construction | 2026 |
| AH Joinery Limited | Construction | 2006 |
| Ahimsa Yama Limited | Real estate | 2022 |
| Ahni Limited | Administrative & support | 2024 |
| Aidan Black Plumbing & Heating Ltd | Construction | 2013 |
| Aidan Strain Electrical Engineering Limited | Construction | 2000 |
| Aidan Strain Management Ltd | Administrative & support | 2010 |
| Aidan Walsh Hairdressing Limited | Other services | 2025 |
| Aidco UK Ltd | Construction | 2026 |
| Aima Opex Ltd | Information & communication | 2024 |
| Air-Tastic Bangor Ltd | Arts & recreation | 2016 |
| Air-Tastic Belfast Ltd | Arts & recreation | 2016 |
| Air-Tastic Craigavon Limited | Arts & recreation | 2018 |
| Air-Tastic Ltd | Arts & recreation | 2016 |
| Air-Tastic Newtownabbey Ltd | Arts & recreation | 2019 |
| Airge Limited | Real estate | 2018 |
| Airmid Academy Ltd | Education | 2023 |
| Airmid Escentuals Ltd | Wholesale & retail | 2017 |
| Airmid Therapies Ltd | Other services | 2017 |
| Airways (Northern Ireland) Limited | Administrative & support | 2013 |
| AJ Fresh Foods Limited | Manufacturing | 2020 |
| AJ Solid Fuels Limited | Wholesale & retail | 2012 |
| AJ Tiles and Flooring Limited | Wholesale & retail | 2020 |
| AJ Trading Limited | Wholesale & retail | 2018 |
| AJC Security N.I Limited | Administrative & support | 2019 |
| Ajma Construction Ltd | Construction | 2023 |
| AJP Renewables Limited | Extraterritorial | 2018 |
| AJQ Electrical Ltd | Construction | 2017 |
| AJR Contracts Ltd | Construction | 2025 |
| AJW Contracts Ltd | Construction | 2019 |
| AJW Training Consultants Ltd | Professional & scientific | 2015 |
| AK Commercials (2019) Ltd | Wholesale & retail | 2019 |
| AK Trading (2019) Ltd | Wholesale & retail | 2019 |
| Akara Robotics UK Limited | Professional & scientific | 2022 |
| Akurro Group Ltd | Professional & scientific | 2020 |
| AL Asar Limited | Wholesale & retail | 2024 |
| AL Carpentry Ltd | Construction | 2023 |
| AL Hair Extensions Limited | Other services | 2020 |
| Al-Pa Properties Ltd | Households | 2018 |
| Alan Black & Co. Limited | Other services | 2007 |
| Albertbridge Apartment Management Limited | Households | 2006 |
| Alchemy Five Consulting Limited | Information & communication | 2020 |
| Aldam Tech Ltd | Manufacturing | 2024 |
| Alder Management LP | | 2017 |
| Alegro Enterprises Ltd | Administrative & support | 2021 |
| Alex ORR Limited | Agriculture & fishing | 2014 |
| Alexandria’S Baby Boutique Ltd | Wholesale & retail | 2019 |
| Alfa Force LP | | 2020 |
| ALI Marine Ltd | Construction | 2021 |
| Alice Oliver Limited | Financial services | 2019 |
| Alive Design Contracts Limited | Construction | 2021 |
| ALL 3 Studio Ltd | Professional & scientific | 2014 |
| ALL Aflame Limited | Wholesale & retail | 2005 |
| ALL Auto Select Group Ltd | Wholesale & retail | 2025 |
| ALL Certs Safety Ltd | Public administration | 2025 |
| ALL Saints Developments ROI Ltd | Hospitality | 2017 |
| ALL Star Recovery & Transportation Limited | Transport & logistics | 2020 |
| ALL Start Car Wash Ltd | Manufacturing | 2025 |
| ALL Weather Industries Ltd | Professional & scientific | 2020 |
| Allcon Ltd | Construction | 2015 |
| Allflax Limited | Wholesale & retail | 2024 |
| Alliance Explore Flooring NI Ltd | Construction | 2022 |