| Ardel Investments Limited | Real estate | 1996 |
| Arden UW Ltd | Financial services | 2019 |
| Ardenlee Avenue Management Limited | Households | 2019 |
| Ardenlee Green Management Company Limited | Households | 1997 |
| Ardenlee Management Company Limited | Households | 2015 |
| Ardenlee Property Management Company Limited | Households | 2004 |
| Ardglass Wines Limited | Wholesale & retail | 2021 |
| Ardilea Properties Ltd | Households | 2020 |
| Ardiles Investments Limited | Real estate | 2008 |
| Ardlea Ltd | Hospitality | 2021 |
| Ardlough Limited | Hospitality | 2013 |
| Ardluce Limited | Information & communication | 2011 |
| Ardmonagh Engineering Ltd | Professional & scientific | 2020 |
| Ardmonagh Family and Community Group Limited | Health & social care | 1997 |
| Ardmore Digital Services Limited | Professional & scientific | 2022 |
| Ardmore Holdings N.I. Limited | Financial services | 2025 |
| Ardmore House (Healthcare) Ltd | Health & social care | 2024 |
| Ardmore House (Holdings) Ltd | Financial services | 2025 |
| Ardmore House (Property) Ltd | Real estate | 2025 |
| Ardmore Housing Management Company Limited | Households | 1999 |
| Ardmore Manor (Phase 2) Limited | Households | 2006 |
| Ardmore Rentals Limited | Real estate | 2018 |
| Ardmore Trade L.P. | | 2017 |
| Ardnagreena House Property Management Limited | Extraterritorial | 2003 |
| Ardnakilla Developments Ltd | Construction | 2019 |
| Ardnavalley Management Company Limited | Real estate | 2009 |
| Ardoyne Afterschools Club | Arts & recreation | 2008 |
| Ardoyne Association | Health & social care | 2016 |
| Ardoyne Bone Community Health & Leisure Ltd | Education | 2017 |
| Ardoyne MMA C.I.C. | Arts & recreation | 2023 |
| Ardoyne Shankill Health Partnership | Health & social care | 2008 |
| Ardoyne Youth Enterprises | Public administration | 2014 |
| Ardrigh Management Company Limited | Households | 1986 |
| Ardross Apartments Management Ltd | Administrative & support | 2008 |
| Ardross Investments Limited | Construction | 2002 |
| Ards & North Down Pest Control Ltd | Administrative & support | 2025 |
| Ards Battery Storage Ltd | Energy | 2021 |
| Ards Building Products (Manufacturing) Limited | Extraterritorial | 1990 |
| Ards Holdings Limited | Professional & scientific | 1973 |
| Ardtalla Consulting Limited | Professional & scientific | 2005 |
| Ardtole Developments Limited | Wholesale & retail | 2016 |
| Ardtole Ltd | Agriculture & fishing | 2021 |
| Ardu Ltd | Financial services | 2015 |
| Ardvarna Holdings Ltd | Financial services | 2021 |
| Area 111 Luminous Life Ltd | Other services | 2021 |
| Area Healthcare Solution Ltd. | Health & social care | 2023 |
| Arena Capital Partners (NI) Limited | Energy | 2015 |
| Arena Energy Holdings Ltd | Financial services | 2021 |
| Arena Healthcare Limited | Health & social care | 2012 |
| Arena Padel Ltd | Arts & recreation | 2025 |
| Arena Wind Markethill Limited | Energy | 2015 |
| Ares Market Services Limited | Energy | 2022 |
| Arete Technology Solutions Ltd | Information & communication | 2014 |
| Arezair Ltd | Wholesale & retail | 2018 |
| ARG Talent Ltd | Administrative & support | 2023 |
| Argent-Ni Limited | Real estate | 2020 |
| Argento Contemporary Jewellery Limited | Wholesale & retail | 2002 |
| Argon Technical Services Ltd | Professional & scientific | 2013 |
| Argonaut Theatre Company Ltd | Arts & recreation | 2025 |
| Argos (N.I.) Ltd | Professional & scientific | 2020 |
| Argyle Buildings Trust | Real estate | 2018 |
| Aria Active Ltd | Wholesale & retail | 2024 |
| Aria-Grace Holdings Limited | Other services | 2025 |
| Arichy Limited | Manufacturing | 2024 |
| Arif Sukxwks Ltd | Wholesale & retail | 2024 |
| Arigho Larmour Wheeler Architects UK Limited | Professional & scientific | 2017 |
| Arilio Ltd | Information & communication | 2015 |
| Arisu Korean Food Ltd | Hospitality | 2025 |
| Aritura Enterprise Limited | Wholesale & retail | 2025 |
| Arize NI Ltd | Wholesale & retail | 2026 |
| Arjo Holdings Ltd | Financial services | 2026 |
| ARK Consult Ltd | Professional & scientific | 2015 |
| ARK Group INT Ltd | Wholesale & retail | 2025 |
| ARK Medical Ltd | Health & social care | 2015 |
| Arkady Limited | Wholesale & retail | 2025 |
| Arke Consultancy Ltd | Other services | 2016 |
| Arken Limited | Real estate | 2000 |
| Arkios Investments Limited | Financial services | 2024 |
| Arkios Wealth Management Limited | Financial services | 2024 |
| ARL Trading Ltd | Wholesale & retail | 2025 |
| Arlee Developments Limited | Extraterritorial | 1996 |
| Arlee Mews Limited | Households | 2000 |
| Arlli Vialf Ltd | Wholesale & retail | 2024 |
| Arlmchop Ltd | Health & social care | 2025 |
| Armaan Resales Limited | Wholesale & retail | 2016 |
| Armada Management Group Ltd | Administrative & support | 2025 |
| Armadillopay (UK) Limited | Financial services | 2023 |
| Armagh 11 Limited | Professional & scientific | 2020 |
| Armagh 14 Limited | Professional & scientific | 2018 |
| Armagh Asphalt Limited | Construction | 2000 |
| Armagh House Limited | Real estate | 2015 |
| Armagh Nail & Spa Ltd | Other services | 2026 |
| Armchair and Rocket Ltd | Information & communication | 2018 |
| Armni Limited | Wholesale & retail | 2018 |
| Armour (Global) Ltd | Information & communication | 2019 |
| Armourguard Security Limited | | 1990 |
| Armsliu Limited | Wholesale & retail | 2025 |
| Armson Management Limited | Professional & scientific | 2012 |
| Armstrong IPR Limited | Professional & scientific | 2011 |
| Armstrongkerr Limited | Professional & scientific | 2016 |