| Aquapure Ltd | Wholesale & retail | 2024 |
| Arabian Automobiles Company Ltd | Wholesale & retail | 2025 |
| Arcol Homes Limited | Real estate | 2026 |
| Ardean Manor Limited | Households | 2003 |
| Ardenlee Capital Ltd | Financial services | 2019 |
| Ardentra Corp Limited | Other services | 2025 |
| Ardmac Contracts Limited | Administrative & support | 1978 |
| Ardmore Publishing Ltd | Wholesale & retail | 2023 |
| Ardwick Partnership Ltd | Wholesale & retail | 2012 |
| Argory Properties Limited | Real estate | 2021 |
| Arkle Developments Ltd | Information & communication | 2021 |
| Arkle NI Holdings Ltd | Information & communication | 2021 |
| Arkle Properties Ltd | Information & communication | 2021 |
| Arkle Property Management Ltd | Information & communication | 2021 |
| Arlesey Holdings Limited | Professional & scientific | 2001 |
| Arlesey Properties Limited | Real estate | 1999 |
| Arlesey Trading Limited | Extraterritorial | 1974 |
| Arloscout Ltd | Professional & scientific | 2024 |
| Armagh Cider Company Ltd | Manufacturing | 2004 |
| Armagh Consulting Limited | Professional & scientific | 2025 |
| Armagh Group Properties Ltd | Real estate | 2022 |
| Armagh Transport Solutions Ltd | Transport & logistics | 2025 |
| Arnold and Lockhart Electrical Limited | Construction | 2017 |
| Arnold Solutions & Consulting Ltd | Professional & scientific | 2024 |
| Arse Ltd | Administrative & support | 2024 |
| Artisan Dessert Studio Ltd | Wholesale & retail | 2026 |
| Artplan Ltd | Manufacturing | 2023 |
| ASD Aerospace Limited | Professional & scientific | 2019 |
| Ashgrove Lodge Management Limited | Households | 2007 |
| Ashgrove Lodge Property Management Ltd | Households | 2016 |
| Aspire (N.I.) | Health & social care | 2016 |
| Astordia Limited | Health & social care | 2025 |
| Atcactiontochange Ltd | Administrative & support | 2024 |
| Athenas Sports Ltd | Manufacturing | 2021 |
| Atni Ltd | Hospitality | 2025 |
| Atpd Limited | Administrative & support | 2024 |
| ATS Equities Ltd | Professional & scientific | 2025 |
| ATS Trusses Ltd | Manufacturing | 2011 |
| Aughalargue Investment Company Ltd | Financial services | 2022 |
| Aughrim Landfill Limited | Water & waste | 2005 |
| Aula Architects Limited | Professional & scientific | 2021 |
| Aura Flame Ltd | Manufacturing | 2021 |
| Auto Worx (Ireland) Ltd | Wholesale & retail | 2021 |
| Autobid UK Ltd | Wholesale & retail | 2014 |
| Autocar N.I. Limited | Wholesale & retail | 2019 |
| Autoclass Motor Company NI Ltd | Wholesale & retail | 2025 |
| Autolocksmithni Limited | Other services | 2015 |
| Automagic Ltd | Wholesale & retail | 2016 |
| Automotive GAS Systems (N.I.) Ltd | Manufacturing | 2013 |
| Autonomy Financial Planning Limited | Financial services | 2011 |
| Autopro Services & Tuning Ltd | Wholesale & retail | 2023 |
| AV Media Ltd | Professional & scientific | 2025 |
| Avenue Road Retail Limited | Wholesale & retail | 2021 |
| Avondale Foods (Craigavon) Limited | Manufacturing | 1981 |
| Avondale Halfpenny Limited | Manufacturing | 2026 |
| Avuk Services Ltd | Transport & logistics | 2018 |
| Axis Systems Limited | Manufacturing | 1999 |
| Aydan Group Ltd | Administrative & support | 2023 |
| Ayra 2017! Limited | Hospitality | 2023 |
| AZ Portadown Limited | Hospitality | 2021 |
| B & C Litter Limited | Wholesale & retail | 2009 |
| B & H Technical Services (N.I.) Ltd | Manufacturing | 2000 |
| B Jones Plumbing and Heating Ltd | Construction | 2017 |
| B N J Holdings Ltd | Households | 2025 |
| B V Construction Consultancy Ltd | Real estate | 2019 |
| B W Jones Limited | Construction | 2017 |
| B&W Road Racing Ltd | Arts & recreation | 2022 |
| B-Tek Battery Services Ltd | Wholesale & retail | 2023 |
| B.B.D.A.&T. Ltd | Financial services | 2026 |
| B.Hanna Landscape and Design Ltd | Administrative & support | 2021 |
| Babadok Expedition Ltd | Transport & logistics | 2024 |
| Back Care Mattress Specialist Ltd | Administrative & support | 2009 |
| Baird Vision Ltd. | Wholesale & retail | 2025 |
| Baker BOY Production Ltd. | Other services | 2018 |
| Balfour Windows (NI) Limited | Construction | 2013 |
| Ballinderry Car Sales Limited | Wholesale & retail | 2012 |
| Ballybreagh Farm Limited | Agriculture & fishing | 2011 |
| Ballydougan Business Units Ltd | Real estate | 2026 |
| Ballydougan Cars Ltd | Wholesale & retail | 2022 |
| Ballydougan Pottery Limited | Manufacturing | 2005 |
| Ballydown Mews Management Limited | Households | 2011 |
| Ballykeel Freight Limited | Transport & logistics | 2002 |
| Ballylisk Car Sales Limited | Wholesale & retail | 2007 |
| Ballylisk Dairies Ltd | Manufacturing | 2017 |
| Ballylisk Vehicle Rentals Ltd | Administrative & support | 2022 |
| Ballymacanallen Community Association Ltd | Other services | 2018 |
| Ballymore Management Company Limited | Real estate | 2004 |
| Ballynacor Estates Ltd | Construction | 2005 |
| Ballynacor Management Ltd | Households | 2005 |
| Ballynagarrick Properties Ltd | Real estate | 2003 |
| Ballynagowan Property Limited | Real estate | 2020 |
| Ballytromery Management Company Limited | Extraterritorial | 2006 |
| Ballytyrone Nurseries Limited | Agriculture & fishing | 2016 |
| Ballywatson Farms Ltd | Agriculture & fishing | 2025 |
| Bama Europa UK Limited | Manufacturing | 1997 |
| Bamboo Chinese Take Away Ltd | Hospitality | 2015 |
| Banbridge Old Vehicle Club Limited | Arts & recreation | 1988 |
| Bann Drinks Ltd | Hospitality | 2012 |
| Bann Hire & Sales Ltd | Administrative & support | 2013 |
| Bann Management Services Ltd | Real estate | 2011 |