| AJR Construction & Joinery Ltd | Construction | 2022 |
| AJS Accommodations Limited | Real estate | 2025 |
| AJS Car Sales Ltd | Wholesale & retail | 2022 |
| Akfp Ltd | Financial services | 1995 |
| Akita Technical Ltd | Professional & scientific | 2019 |
| Alamarr Limited | Public administration | 2021 |
| Alaneil Ltd | Wholesale & retail | 2024 |
| Alchemy Male Image Ltd | Other services | 2025 |
| Aldersgate House Limited | Professional & scientific | 2011 |
| Aleapow Technology Limited | Wholesale & retail | 2025 |
| Alexandra Hill Developments Ltd | Construction | 2024 |
| Algoenterprises Ltd | Wholesale & retail | 2023 |
| Algorithmic Perspectives Ltd | Information & communication | 2023 |
| Algozone Ltd | Wholesale & retail | 2024 |
| ALI Obstetrics Limited | Health & social care | 2026 |
| Alice Nails 60 Ltd | Other services | 2025 |
| ALL Active (N.I.) Ltd | Arts & recreation | 2021 |
| ALL Fresh Limited | Wholesale & retail | 2026 |
| Allan Greenfield Plumbing Ltd | Construction | 2014 |
| Allied Equipment Limited | Manufacturing | 1969 |
| Alloy Trade LP | | 2022 |
| Allure Hair Co Limited | Other services | 2013 |
| Almix Media Ltd | Information & communication | 2022 |
| Alpha Automation Limited | Construction | 2015 |
| Alpha Health Care Assistant Ltd | Health & social care | 2021 |
| Alphabyte Holdings Limited | Financial services | 2025 |
| ALR Trading Limited | Manufacturing | 2018 |
| Alternity Biogas Energy Limited | Energy | 2015 |
| Altesc Ltd | Arts & recreation | 2017 |
| Aluminium & Plastics Systems (Holdings) Ltd | Professional & scientific | 2015 |
| Aluminium & Plastics Systems Limited | Wholesale & retail | 2000 |
| Alwc Limited | Information & communication | 2017 |
| Amac Logistics Ltd | Wholesale & retail | 2006 |
| Amag Logistics Limited | Transport & logistics | 2022 |
| Amaigo Ltd | Information & communication | 2026 |
| Amaina Ltd. | Transport & logistics | 2010 |
| Amatak Development Limited | Construction | 2019 |
| Amazingly Artisan Limited | Hospitality | 2014 |
| Ametrine Care Services Ltd | Administrative & support | 2022 |
| Amity Medtech Limited | Information & communication | 2026 |
| Ammo Welding Ltd | Construction | 2026 |
| Amphora NDT Ltd | Professional & scientific | 2020 |
| Amphora Technologies Limited | Manufacturing | 2014 |
| Analab Analytical Laboratory Supplies Limited | Professional & scientific | 1994 |
| Ancam Tech Limited | Wholesale & retail | 2024 |
| Ancg Limited | Real estate | 2017 |
| AND WE Keep Limited | Manufacturing | 2021 |
| Andersonstown Meats Ltd | Wholesale & retail | 2021 |
| Andrew Foods Limited | Extraterritorial | 1974 |
| Andrew Group Ltd | Wholesale & retail | 2020 |
| Andrew Honeycomb Ltd | Wholesale & retail | 2009 |
| Andrew Ingredients Ltd | Wholesale & retail | 1969 |
| Andrew Markey Ltd | Construction | 2023 |
| Andrew of Hillsborough Limited | Professional & scientific | 1998 |
| Andrew Rose Limited | Wholesale & retail | 2025 |
| Angello Development Foundation | Other services | 2010 |
| ANNS14 Limited | Real estate | 2019 |
| Anoarah Ltd | Health & social care | 2026 |
| Anrai Ltd | Administrative & support | 2022 |
| Anshika & Co Ltd | Wholesale & retail | 2023 |
| Antana Limited | Hospitality | 2023 |
| Apache Pizza (Lisburn) 786 Ltd | Hospitality | 2019 |
| Apea Truck & Trailer Parts Ltd | Extraterritorial | 2013 |
| Apex 3PL Ltd | Transport & logistics | 2026 |
| Apex Rail Projects Limited | Construction | 2024 |
| Apollo Road Hand Car Wash Ltd | Administrative & support | 2020 |
| Apple Tree Farm Ltd | Agriculture & fishing | 2016 |
| Apples Androids and Drones N. I. Limited | Wholesale & retail | 2023 |
| Appletree Fabrics Limited | Extraterritorial | 1995 |
| Applied Marketing Group Limited | Professional & scientific | 2021 |
| APS Top Co Limited | Financial services | 2022 |
| APT Innovations Ltd | Wholesale & retail | 2011 |
| Aqua Dog Hydrotherapy Ltd | Other services | 2015 |
| Aquatib Ltd | Construction | 2026 |
| Aranden Properties Ltd | Real estate | 2016 |
| ARC Intellicare Limited | Manufacturing | 2020 |
| Arches Blow DRY Bar Limited | Other services | 2012 |
| Architectural Stone Ltd | Manufacturing | 1995 |
| Arcus Cleaning Systems Ltd | Manufacturing | 2019 |
| Ardent Wealth Limited | Professional & scientific | 2020 |
| Ardfoyle Trust | Real estate | 1983 |
| Ardgowan Advisory Ltd | Administrative & support | 2014 |
| Ardis Building Ltd | Construction | 2016 |
| Ardress Developments Ltd | Construction | 2015 |
| Ardtir Holdings Limited | Financial services | 2020 |
| Arezzo Verde Limited | Manufacturing | 2023 |
| Arisum Ltd | Hospitality | 2021 |
| Aritar Limited | Extraterritorial | 2021 |
| ARK Branded Products Ltd | Manufacturing | 2019 |
| Arlo Contracts Ltd | Construction | 2026 |
| Armagh Specsavers Limited | Wholesale & retail | 2025 |
| Armcul Investments Ltd | Financial services | 2026 |
| Armoy Wind Farm Limited | Energy | 2022 |
| Armstrong Capital Limited | Real estate | 2024 |
| Armstrong Farm T/A Hillview Farm Ltd | Agriculture & fishing | 2026 |
| Armstrong Plumbing & Heating (NI) Ltd | Construction | 2014 |
| Armstrong Properties Incorporated Ltd | Real estate | 2025 |
| Armstrong Surfacing Ltd | Construction | 2017 |
| Armstrong's Farm Limited | Energy | 2016 |
| Aroma at the Olde Mill Limited | Manufacturing | 2021 |