| (Nr)Ni Contracts Limited | Construction | 2025 |
| 10-14 Ltd | Hospitality | 2019 |
| 1014 Property Group Ltd | Real estate | 2024 |
| 105 Dublin Road Management Company Limited | Other services | 2001 |
| 109-111 Cliftonville Road Management Limited | Real estate | 2007 |
| 1130 Properties Ltd | Real estate | 2014 |
| 12 Seaview Management Limited | Households | 2025 |
| 123 Deliver Ltd | Transport & logistics | 2026 |
| 15 Lisburn Road Management Ltd | Households | 2017 |
| 21ST Century Back Care Moira Ltd | Health & social care | 2013 |
| 26 Extreme Ltd | Arts & recreation | 2009 |
| 3 Interior Contracts Limited | Construction | 2009 |
| 3 Interior Holdings Limited | Financial services | 2018 |
| 3 Sisters & Co Coffee Ltd | Hospitality | 2026 |
| 371/375 Antrim Road Management Company Limited | Households | 2005 |
| 3JCR Limited | Professional & scientific | 2023 |
| 3Q Properties Ltd | Construction | 2024 |
| 3R Mobility Ltd | Health & social care | 2016 |
| 3RD Digital Limited | Information & communication | 2016 |
| 4 Aces CC Limited | Wholesale & retail | 2025 |
| 4 Wallace Motors Ltd | Wholesale & retail | 2024 |
| 45 William Street Ltd | Real estate | 2024 |
| 46 Mill Street Ltd | Administrative & support | 2022 |
| 4C the Bakery Ltd | Manufacturing | 2025 |
| 50/50NI Limited | Other services | 2024 |
| 5C Construction Ltd | Construction | 2018 |
| 7 of 9 N. I. Ltd | Wholesale & retail | 2026 |
| 8 John Mitchell Place Limited | Real estate | 2011 |
| 89NINETY Ltd | Information & communication | 2022 |
| A "N" D Care Services Ltd | Health & social care | 2019 |
| A & E Plant Hire Ltd | Administrative & support | 2021 |
| A & M Haughian Limited | Construction | 2003 |
| A & S O’Rourke Limited | Households | 2026 |
| A B Safety Limited | Professional & scientific | 2022 |
| A J Furniture Agencies Ltd | Wholesale & retail | 2014 |
| A Kelly Services Ltd | Transport & logistics | 2021 |
| A Mcguinness Consultancy Ltd | Professional & scientific | 2025 |
| A O'Callaghan Contracts Ltd | Construction | 2022 |
| A Piece of Cake Limited | Manufacturing | 2004 |
| A Robinson & SON Ltd | Manufacturing | 2021 |
| A Young Electrical Ltd | Construction | 2019 |
| A&A Haugh Ltd | Construction | 2019 |
| A&Asf Limited | Wholesale & retail | 2018 |
| A&C Nugent Developments Ltd | Real estate | 2025 |
| A&D Farms Ltd | Agriculture & fishing | 2011 |
| A&E Discount Supplies Ltd | Administrative & support | 2020 |
| A&J Ecom Limited | Wholesale & retail | 2025 |
| A&O Bros Limited | Wholesale & retail | 2025 |
| A&T Management Limited | Administrative & support | 2010 |
| A-Wear Limited+ | | 2007 |
| A-Z Property Solutions (N.I.) Limited | Real estate | 2017 |
| A.B.M. Auto Repairs Ltd | Wholesale & retail | 2020 |
| A.C.T. Stainless Steel Limited | Manufacturing | 2017 |
| A.L. Quads Ltd | Wholesale & retail | 2023 |
| A.M. & S.M. Enterprises Limited | Agriculture & fishing | 2009 |
| A.R. Marine Engineering Limited | Professional & scientific | 2012 |
| A.T.A.I Aesthetic Training Academy Ltd | Education | 2021 |
| A1 Plumbing Ltd | Construction | 2018 |
| A1 Safety & Workwear Supplies Ltd | Wholesale & retail | 2013 |
| A1 Training Limited | Professional & scientific | 2013 |
| A29 Fuel Centre Ltd | Wholesale & retail | 2014 |
| AAB Group Accountants Limited | Professional & scientific | 1989 |
| Aatom Developments Ltd | Real estate | 2026 |
| AB Aerotech Ltd | Manufacturing | 2024 |
| AB Aesthetics & Skincare Ltd | Health & social care | 2025 |
| AB Pharma Consultancy Ltd | Other services | 2022 |
| AB Trophy's Ltd | Wholesale & retail | 2011 |
| Abbey Construction Ltd | Construction | 2018 |
| ABC Community Ssdab Ltd | Information & communication | 2022 |
| ABC Steel Supplies LLP | | 2005 |
| Abco Performance Ltd | Arts & recreation | 2025 |
| Abergeldie Complex Infrastructure Limited | Construction | 2017 |
| Abilot Limited | Health & social care | 2026 |
| Abound Business LP | | 2017 |
| Aboxx Ltd | Transport & logistics | 2025 |
| AC Male Grooming (Armagh) Ltd | Other services | 2026 |
| AC Power (N.I.) Limited | Construction | 2019 |
| Acadan Ltd | Health & social care | 2025 |
| Accelarr Ltd | Professional & scientific | 2022 |
| Accelerated Learning Ltd | Education | 2022 |
| Access Media Adventure Ltd | Other services | 2023 |
| Accountancy-Tax.Ie Limited | Professional & scientific | 2017 |
| Ace Auto Styling Limited | Wholesale & retail | 2026 |
| Ace Competition Ltd | Arts & recreation | 2019 |
| Ace Control Systems Limited | Energy | 2006 |
| Achilles Fishing Ltd | Agriculture & fishing | 2016 |
| Acquos EUR Ltd | Professional & scientific | 2021 |
| ACS Project Management Ltd | Construction | 2023 |
| Acsb Group Ltd | Wholesale & retail | 2024 |
| Acscu Limited | Wholesale & retail | 2025 |
| ACT + Acre Ireland Limited | Wholesale & retail | 2021 |
| Actify Property Solutions Limited | Real estate | 2018 |
| Active Foot Solutions Ltd | Health & social care | 2023 |
| Active Lifting Services Limited | Construction | 2024 |
| Acton Environmental Ltd | Agriculture & fishing | 2021 |
| Acushla Training Ltd | Professional & scientific | 2020 |
| AD Martin Haulage Ltd | Transport & logistics | 2024 |
| Adavoyle Farm Enterprises Limited | Agriculture & fishing | 2019 |
| Adavoyle Ltd | Real estate | 2021 |
| Addemo Press Limited | Information & communication | 1986 |