| 121 Direct Care Limited | Health & social care | 2022 |
| 1ST Choice Plastics NI Ltd | Manufacturing | 2023 |
| 2 and 4 Wheel Motorsport Limited | Arts & recreation | 2002 |
| 2020 Gifted Ltd | Wholesale & retail | 2021 |
| 31 END Terrace Ltd | Hospitality | 2024 |
| 45DEGREE Prep Ltd | Professional & scientific | 2019 |
| 4BE Limited | Construction | 2023 |
| 54N Ltd | Information & communication | 2020 |
| 9 Marine Limited | Hospitality | 2024 |
| 9YARDS Property Ltd | Professional & scientific | 2011 |
| A Mclean & Co (N.I.) Ltd | Professional & scientific | 2024 |
| A T Fencing Ltd | Construction | 2025 |
| A&M (N.I.) Ltd | Administrative & support | 2025 |
| A&Md Holdings Limited | Construction | 2022 |
| A&Pd Holdings Limited | Construction | 2022 |
| A1 Global Aviation Services Limited | Transport & logistics | 2022 |
| AB Fitness Limited | Arts & recreation | 2019 |
| AB Optical LAB Ltd | Manufacturing | 2010 |
| Abbey Carpets & Flooring Ltd | Construction | 2018 |
| Abbey Insurance Brokers Limited | Financial services | 2005 |
| Abbey Upholsterers Limited | Manufacturing | 1975 |
| ABH Electricalni Limited | Construction | 2022 |
| About Face Beauty Ltd | Other services | 2012 |
| AC Automation (U.K.) Limited | Manufacturing | 2000 |
| ACA Energy LLP | | 2010 |
| ACA Generation LLP | | 2012 |
| Acapple Construction Limited | Construction | 2009 |
| Ace Computer Solutions NI Ltd | Information & communication | 2011 |
| Ace My Test Ltd | Information & communication | 2025 |
| Acorn Aviation Ltd | Manufacturing | 2024 |
| Acorn Blinds NI Limited | Manufacturing | 2014 |
| Acorn Management Co (NI) Limited | Households | 2006 |
| Adept Property and Investment Services Limited | Financial services | 2016 |
| Admc Property Limited | Real estate | 2016 |
| Admiral Care Services (NI) Limited | Health & social care | 2014 |
| Adonis Developments Limited | Real estate | 1996 |
| ADP Diagnostics Ltd | Health & social care | 2005 |
| ADR Consulting Ltd | Professional & scientific | 2024 |
| Adrian Gallagher Ltd | Financial services | 2019 |
| Advanced Lifting & Rigging Solutions Ltd | Construction | 2018 |
| Advanced Sensors Limited | Manufacturing | 2005 |
| Aestheticsni Ltd | Health & social care | 2024 |
| Afmf Holdings Ltd | Financial services | 2024 |
| Afmf Property Limited | Real estate | 2022 |
| Agy-Solutions Ltd | Professional & scientific | 2026 |
| Air-Fun Ltd | Administrative & support | 2020 |
| Aislinn Court Management Limited | Administrative & support | 1998 |
| Aizelmcgarry Limited | Information & communication | 2020 |
| Aj's Snack Box Ltd | Hospitality | 2026 |
| AK Lifts Ltd | Construction | 2020 |
| Alana’S Nail Salon Ltd | Other services | 2026 |
| Alderdice Properties Limited | Construction | 2007 |
| Aletheia Consultancies Ltd | Professional & scientific | 2018 |
| Alexandra Avenue Management Company Limited | Households | 2006 |
| Align Pilates and Physiotherapy Ltd | Other services | 2026 |
| ALL Cleaned UP Ireland Ltd | Administrative & support | 2020 |
| Allshutter Doors Ltd | Construction | 2011 |
| Allure Beauty Holdings Ltd | Other services | 2018 |
| Almi Smart Solutions Ltd | Information & communication | 2024 |
| Alpina Developments Ltd | Construction | 2021 |
| Alsa Developments Ltd | Construction | 2012 |
| Amazing Rewards Program Ltd | Wholesale & retail | 2025 |
| AME (NI) Limited | Extraterritorial | 2007 |
| Amhatrading Ltd | Wholesale & retail | 2025 |
| AMI Ireland | Other services | 2014 |
| Aml-Soft Ltd | Information & communication | 2004 |
| AMP Properties (N.I.) Ltd | Arts & recreation | 2025 |
| Andy Finn Transport Services Ltd | Transport & logistics | 2026 |
| Angel Square Food (Northern Ireland) Limited | Extraterritorial | 2020 |
| Antrim Quality Lamb Ltd | Agriculture & fishing | 2000 |
| Antrim Sports Club Ltd | Arts & recreation | 2020 |
| Aontas Films Ltd | Information & communication | 2023 |
| Apex Installations & Renewable Ltd | Professional & scientific | 2026 |
| Applewood Sherwood Ltd | Administrative & support | 2019 |
| AR Aerospace Ltd | Manufacturing | 2016 |
| Ardent Energy Ltd | Professional & scientific | 2016 |
| Arkham Holdings Ltd | Financial services | 2024 |
| Armageddon Electrical Ltd | Construction | 2025 |
| Arosa Mineral Management Company Limited | Households | 2006 |
| Artemis Business Consulting Limited | Professional & scientific | 2025 |
| Asap Access Ltd | Manufacturing | 2014 |
| ASC Performance and Tuning Ltd | Wholesale & retail | 2023 |
| Ashford Developments (NI) Ltd | Construction | 2015 |
| Ashgrove Heights Limited | Extraterritorial | 2020 |
| Ashton Group Ltd | Wholesale & retail | 2021 |
| ASP Building Limited | Construction | 2026 |
| Association of Northern Ireland Car Clubs Limited | Arts & recreation | 2023 |
| Athena Marketing Consultancy Ltd | Professional & scientific | 2023 |
| Atherton Square Management Company Limited | Real estate | 2019 |
| Atlas Sportstech Holdings Ltd | Information & communication | 2021 |
| Audio International Ltd | Professional & scientific | 2003 |
| Autocomms Ltd | Information & communication | 2026 |
| Autofinish Carrick Limited | Wholesale & retail | 2020 |
| Autoline Direct Insurance Consultants Limited | Financial services | 1987 |
| Avenue Road Property Management Ltd | Households | 2003 |
| Aviometrics Ltd | Manufacturing | 2024 |
| Avondale Estate Management Company Limited | Real estate | 2019 |
| Avonmore Court Management Limited | Households | 2009 |
| AW Decor Ltd | Construction | 2026 |
| AW Power Engineering Ltd | Professional & scientific | 2021 |