| Alpha Omega the Beginning Limited | Information & communication | 2023 |
| Alshar Group Limited | Financial services | 2021 |
| Altmore I T U K Limited | Information & communication | 2012 |
| Altnagowna Ltd | Professional & scientific | 2020 |
| AM Farm Services Limited | Agriculture & fishing | 2025 |
| AM Glazing & Joinery Ltd | Construction | 2017 |
| Amber Elements Ltd | Manufacturing | 2025 |
| AMD Maintenance and Facilities Ltd | Construction | 2021 |
| Amdc Ltd | Professional & scientific | 2020 |
| AME Construction Ltd | Construction | 2020 |
| AMH (N.I.) Ltd | Wholesale & retail | 2018 |
| AMK Painting Ltd | Construction | 2019 |
| AMO E-Commerce Limited | Wholesale & retail | 2025 |
| Amulet Developments NI Limited | Real estate | 2015 |
| Amwaj Aviation Auditing Limited | Professional & scientific | 2021 |
| AMY Warwick Physio Ltd | Health & social care | 2026 |
| Anderson Kelly Distribution Ltd | Wholesale & retail | 2023 |
| Andre Charles Limited | Professional & scientific | 2024 |
| Angel Companion Limited | Health & social care | 2025 |
| Angelofminejewellery Ltd | Wholesale & retail | 2023 |
| Anncor Ltd | Construction | 2017 |
| Antrim Energy Group Ltd | Financial services | 2026 |
| Antrim Energy Ltd | Financial services | 2026 |
| Anzo Sports Management Limited | Professional & scientific | 2018 |
| Apache Peking Ltd | Hospitality | 2022 |
| Apeer Limited | Manufacturing | 2017 |
| Apex Fitting Limited | Construction | 2024 |
| Apex Genetics Ltd | Agriculture & fishing | 2025 |
| Apex Hot Tubs and Saunas Limited | Wholesale & retail | 2026 |
| Apex Landscaping & Gardening Ltd | Administrative & support | 2025 |
| Apex Steel Buildings Ltd | Wholesale & retail | 2023 |
| Apex Verandas Limited | Wholesale & retail | 2022 |
| Appletee Ltd | Construction | 2018 |
| Applied ICT LP | | 2012 |
| Applied Technologies Group Ltd | Information & communication | 2018 |
| AR Preloved Limited | Wholesale & retail | 2024 |
| ARA Hygiene Ltd | Manufacturing | 2015 |
| Aralia Lane Limited | Wholesale & retail | 2018 |
| ARC Data Solutions Ltd | Information & communication | 2019 |
| Arc-Met Ltd | Manufacturing | 2022 |
| Arck Property Limited | Real estate | 2025 |
| Ardilaun Ltd | Real estate | 2005 |
| Ardmoyle Consulting Limited | Information & communication | 2024 |
| Ardnamurchan Holdings Limited | Manufacturing | 2019 |
| Ardverna Energy Limited | Extraterritorial | 1985 |
| Arktis Endurance Textiles Ltd | Manufacturing | 2017 |
| Armstrong Quattropillar Ltd | Manufacturing | 2022 |
| Arris Edge Ltd | Real estate | 2009 |
| Artemis Digital Solutions Ltd | Information & communication | 2022 |
| Artis (Europe) Limited | Professional & scientific | 2009 |
| Artoges Limited | Financial services | 2026 |
| AS Exterior Cleaning Ltd | Administrative & support | 2024 |
| Ashgrove Conservatories and Sunrooms Limited | Construction | 2008 |
| Ashgrove Contract Furniture Limited | Manufacturing | 2000 |
| Ashgrove Precision Engineering Limited | Professional & scientific | 2012 |
| Asian Corner Ballymena Ltd | Wholesale & retail | 2025 |
| Asian Taste 2025 Ltd | Hospitality | 2025 |
| ASM (NI) Developments Limited | Real estate | 2007 |
| Astioum Ltd | Manufacturing | 2022 |
| Astute Construction Limited | Construction | 2005 |
| Astute Financial Advice Group Limited | Financial services | 2002 |
| Astute Financial Limited | Financial services | 2002 |
| ATG Connections Ltd | Information & communication | 2026 |
| Atlantic Clinical Packaging UK Ltd | Wholesale & retail | 2024 |
| Atlas Smart Technologies Ltd | Information & communication | 2021 |
| Aughavarry Farms Limited | Agriculture & fishing | 2026 |
| Authentic Alps Ltd | Other services | 2005 |
| Automation Dynamix Ltd | Professional & scientific | 2025 |
| Autopro Cleaning Ltd | Administrative & support | 2020 |
| Autotune (NI) Limited | Manufacturing | 2014 |
| Aventina-Spencer UK Limited | Manufacturing | 2022 |
| Avipro Business Consulting Ltd | Professional & scientific | 2024 |
| Avogue Construction Limited | Construction | 2015 |
| Awardboard (Ireland) Ltd | Manufacturing | 2021 |
| Aybece Ltd | Administrative & support | 2026 |
| Azam Foods 2025 Ltd | Hospitality | 2025 |
| B Express Limited | Information & communication | 2018 |
| Badger Tales Ltd | Administrative & support | 2025 |
| Baird Electrical Contractors Ltd | Construction | 2016 |
| Balance IE Limited | Health & social care | 2021 |
| Ballantine Building Solutions Ltd | Construction | 2020 |
| Ballee & Harryville Community Enterprises | Administrative & support | 2007 |
| Ballee Mews Management Company Limited | Extraterritorial | 2008 |
| Ballsallagh Sports Horses Ltd | Agriculture & fishing | 2023 |
| Ballybollan Farms Ltd | Agriculture & fishing | 2024 |
| Ballyclosh Ltd | Wholesale & retail | 2024 |
| Ballyconnelly Investments Limited | Arts & recreation | 2020 |
| Ballycraigy Medical Limited | Health & social care | 2012 |
| Ballycreggy Limited | Real estate | 2021 |
| Ballydunmaul Properties Limited | Real estate | 2005 |
| Ballygally Holiday Apartments Limited | Hospitality | 2024 |
| Ballygarvey Developments Ltd | Construction | 2021 |
| Ballygarvey Holdings Ltd | Financial services | 2020 |
| Ballygarvey Investments Limited | Financial services | 1908 |
| Ballygarvey Mews Management Ltd | Administrative & support | 2014 |
| Ballygolan Ltd | Construction | 2023 |
| Ballykeel 1 Moving Forward Ltd | Health & social care | 2026 |
| Ballykennedy Holdings Limited | Financial services | 2023 |
| Ballylesson Enterprises Ltd | Construction | 2022 |
| Ballylesson GUN Club Limited | Arts & recreation | 2026 |