| 104 Old Mill Grange Ltd | Real estate | 2022 |
| 15 the Crescent Management Limited | Households | 2000 |
| 18 Dental Ltd | Health & social care | 2021 |
| 23KASA Ltd | Information & communication | 2024 |
| 246 Consulting Ltd | Professional & scientific | 2025 |
| 3 Oaks Studios Ltd | Information & communication | 2025 |
| 4 Moksh Limited | Hospitality | 2024 |
| 5 Opportunities Limited | Wholesale & retail | 2025 |
| 5 Star Kitchens (NI) Ltd | Manufacturing | 2021 |
| 50 CAL Detailing Limited | Wholesale & retail | 2013 |
| A Harte Joinery Ltd | Construction | 2024 |
| A Mcilrath & SON Ltd | Wholesale & retail | 2021 |
| A Mckee & Co Limited | Agriculture & fishing | 2006 |
| A O'Neill Holdings Limited | Financial services | 2018 |
| A Pollock Sales & Hire Ltd | Administrative & support | 2014 |
| A Study in Scarlet Limited | Wholesale & retail | 2024 |
| A&M Oriental Foods Limited | Wholesale & retail | 2023 |
| A. Diamond & SON (Timber) Limited | Manufacturing | 1971 |
| Abcd Trading Ltd | Financial services | 2023 |
| Acca Preventive Health Ltd | Health & social care | 2023 |
| Accelerated Progress UN Limited | Information & communication | 2026 |
| Ace Properties Developments (NI) Ltd | Real estate | 2026 |
| Acorn IT Solutions Limited | Information & communication | 2002 |
| Acorn the Business Centre Ltd | Real estate | 1995 |
| ADJ 97 Properties Limited | Real estate | 2024 |
| Admiration Holdings Ltd | Hospitality | 2025 |
| Adpf LLP | | 2017 |
| Advanced Overwatch Limited | Construction | 2017 |
| AEC Retail Limited | Wholesale & retail | 2017 |
| Aghadowey Dairy Farmers Ltd | Professional & scientific | 2003 |
| Agivey Anglers Association Ltd | Arts & recreation | 2013 |
| Agivey Fit OUT Ltd | Construction | 2026 |
| Agivey Holdings Limited | Financial services | 2021 |
| Agivey Properties Limited | Real estate | 2003 |
| Agivey Trading Limited | Wholesale & retail | 2023 |
| AGM Solutions Ltd | Professional & scientific | 2026 |
| AH Steel Limited | Construction | 2004 |
| Airautomate Ltd | Manufacturing | 2023 |
| Aird Services Limited | Households | 2000 |
| Aisha Healthcare Services Ltd | Health & social care | 2023 |
| AJ Express Freight Limited | Transport & logistics | 2015 |
| AJ Joinery and Maintenance Ltd | Construction | 2023 |
| Akbar Immigration Law Chambers Limited | Professional & scientific | 2016 |
| Alan Jackson Design Ltd | Professional & scientific | 2014 |
| Alderhill Digital Ltd | Information & communication | 2017 |
| Alex.Dickson & Sons,Limited | Financial services | 1900 |
| ALF Logistics Ltd | Transport & logistics | 2020 |
| Alison Campbell Soft Furnishings Ltd | Wholesale & retail | 2012 |
| ALL Sport Autographs Ltd | Wholesale & retail | 2025 |
| Allta Disco Wines Limited | Wholesale & retail | 2025 |
| Almonry Limited | Energy | 1993 |
| Altiora Digital Ltd | Information & communication | 2025 |
| Altmore One Management Limited | Households | 2016 |
| Altware Ltd | Information & communication | 2019 |
| AMA Clinic Ltd | Health & social care | 2025 |
| Amaris (North Coast) Limited | Health & social care | 2016 |
| AMC Crane Hire Limited | Administrative & support | 2018 |
| AN Stoirm Limited | Wholesale & retail | 2024 |
| Ancient Ancestors Ltd | Arts & recreation | 2020 |
| Andena Grange Management Limited | Households | 2004 |
| Anderson Gillan Barr Limited | Professional & scientific | 2012 |
| Andrews Private Capital Limited | Financial services | 2020 |
| Angel of Hope Memorial Garden Limited | Other services | 2015 |
| Anita Flavina Limited | Wholesale & retail | 2016 |
| Annie's Traditional Food Ltd | Manufacturing | 2009 |
| Antrim Gardens Management Company Limited | Households | 2018 |
| AOE Property | Construction | 2022 |
| Apca Contracts Limited | Construction | 2021 |
| Apex Protein NI Limited | Wholesale & retail | 2020 |
| Apperley Fine Foods Limited | Hospitality | 2020 |
| Aquaterra Adventures Limited | Arts & recreation | 2025 |
| Arbour Living (NI) Limited | Construction | 2026 |
| ARC Streaming Limited | Financial services | 2025 |
| Arcadia Studio Rentals Limited | Hospitality | 2025 |
| Arch Isle Ltd | Hospitality | 2021 |
| Arch Thomas Security and Resourcing Ltd | Administrative & support | 2025 |
| Archi TEC Services Ltd | Construction | 2024 |
| Arcmed Ltd | Health & social care | 2010 |
| ARD - Dorragh Cattle Breeders Ltd. | Agriculture & fishing | 1988 |
| ARD Carraig Management Limited | Households | 2003 |
| Ardess Demesne Limited | Extraterritorial | 2006 |
| Ardhowen Cafe and Bar Ltd | Hospitality | 2022 |
| Ardina Flooring Limited | Construction | 2018 |
| Ardreagh Catering Ltd | Manufacturing | 2026 |
| Ardreagh Farms Ltd | Agriculture & fishing | 2026 |
| ARK Landscaping Ltd | Administrative & support | 2023 |
| Arloanco Limited | Real estate | 2016 |
| Armstrong Green Energy Ltd | Energy | 2013 |
| Armstrong Medical Ltd | Manufacturing | 1991 |
| Arthur Investments Limited | Real estate | 2016 |
| Articlave Daycare Nursery Limited | Health & social care | 2013 |
| Asbestos Management Company (Ireland) Limited | Water & waste | 2005 |
| Ashbrook Fields Management Company Limited | Households | 2012 |
| Ashco (NI) Limited | Financial services | 2005 |
| Ashlea Cottages Ltd | Households | 2019 |
| Aspire Community CIC | Wholesale & retail | 2023 |
| Aspire Media N.I. CIC | Information & communication | 2022 |
| Aspire Property Management Solutions Limited | Households | 2018 |
| AT Environmental Services Ltd | Water & waste | 2012 |
| Atalanta Operations Limited | Professional & scientific | 2026 |