| Anseo Ltd | Information & communication | 2017 |
| Antrim & Newtownabbey Seniors' Forum | Health & social care | 2001 |
| Antrim Autoparts Limited | Wholesale & retail | 2003 |
| Antrim Coast Distribution Ltd | Wholesale & retail | 2025 |
| Antrim Homes Ltd | Real estate | 2019 |
| Antrim Properties Mallusk Limited | Real estate | 2006 |
| AOC Coaching Ltd | Education | 2025 |
| AOS Tech Ltd | Wholesale & retail | 2023 |
| Aovswap Ltd | Real estate | 2026 |
| Appreciating YOU Counselling and Supervision Ltd | Health & social care | 2025 |
| APS Learning Ltd | Information & communication | 2007 |
| Aquaforce 2009 Ltd | Construction | 2011 |
| Aquawash (N.I.) Ltd | Other services | 2013 |
| AR Belfast Ltd | Hospitality | 2023 |
| AR Medical Billing Services Ltd | Professional & scientific | 2021 |
| Arclalor Ltd | Real estate | 2022 |
| Arco Gilpins Limited | Extraterritorial | 1940 |
| Ardbarron Trust Limited | Professional & scientific | 1985 |
| Arlo Consultancy Ltd | Health & social care | 2021 |
| Armagh City Hotel Limited | Hospitality | 1996 |
| Armatas Fire & Security Ltd | Administrative & support | 2017 |
| Armstrong Solicitors (NI) Limited | Professional & scientific | 2012 |
| Arroll Ltd | Wholesale & retail | 2013 |
| Art Facilities Management Ltd | Administrative & support | 2025 |
| Arthur & Co Estates Ltd | Real estate | 2025 |
| ASG Property Ltd | Real estate | 2024 |
| Ashbourne Property Management Limited | Real estate | 2007 |
| Ashcroft Trailer Hire Limited | Administrative & support | 1985 |
| Ashegrove Property Services Ltd | Real estate | 2025 |
| Asheila Distributions Ltd | Wholesale & retail | 2026 |
| Ashers Baking Company Limited | Manufacturing | 2004 |
| Ashley Mcnamara Studios Ltd | Wholesale & retail | 2020 |
| Ashvale Tobacco Ltd | Wholesale & retail | 2025 |
| Asian Express 2024 Ltd | Hospitality | 2024 |
| Asian Express Ltd | Hospitality | 2019 |
| Asrm Construction Ltd | Construction | 2026 |
| Asura Financial Ltd | Financial services | 2007 |
| AT Professional Services Limited | Professional & scientific | 2012 |
| ATB Corporate Limited | Administrative & support | 2024 |
| ATC Systems Limited | Manufacturing | 1999 |
| Atlas Car Sales Ltd | Wholesale & retail | 2020 |
| Atni Properties Limited | Real estate | 2019 |
| Atomic Lens Limited | Information & communication | 2019 |
| Atri Belfast Ltd | Hospitality | 2025 |
| Atticus NI Limited | Professional & scientific | 2015 |
| Audiolevel Ltd | Wholesale & retail | 2018 |
| Autobell Ltd | Wholesale & retail | 2018 |
| Autocomponents (NI) Limited | Wholesale & retail | 2000 |
| Automatic Doors NIR Ltd | Construction | 2025 |
| Automatic Gate Store Ltd | Wholesale & retail | 2026 |
| Avid Audio Visual Ltd | Information & communication | 2024 |
| Axalux Ltd | Wholesale & retail | 2015 |
| Axflow (NI) Limited | Manufacturing | 2015 |
| Ayla Hand Car Wash Ltd | Administrative & support | 2026 |
| B a Mccartney Ltd | Wholesale & retail | 2011 |
| B Creighton Contractors Limited | Construction | 2019 |
| B Driver Ltd | Transport & logistics | 2025 |
| B Trading Ltd | Hospitality | 2023 |
| B.A.F. Developments Limited | Administrative & support | 1991 |
| Babylife Ltd | Wholesale & retail | 2019 |
| BAJ Aviation Limited | Manufacturing | 2025 |
| Ballyclare's Hand Car Wash Ltd | Administrative & support | 2022 |
| Ballycraigy Properties Limited | Real estate | 2013 |
| Ballyhill Holdings Ltd | Wholesale & retail | 2025 |
| Ballymaconnell Private Nursing Home Limited | Health & social care | 1989 |
| Ballyvesey Lodge Management Co Ltd | Households | 2010 |
| Balmoral View Apartments Ltd | Real estate | 2005 |
| Bandera Roja Limited | Administrative & support | 2019 |
| Bannon Property Services Limited | Real estate | 2025 |
| Barista Coffee House (NI) Limited | Hospitality | 2011 |
| Bark Kennels Limited | Agriculture & fishing | 2025 |
| Barleymont N.I. Limited | Construction | 2026 |
| Baxter Inns Limited | Hospitality | 2015 |
| BCC Electrical Services Ltd | Construction | 2024 |
| Bccm Plant Ltd | Administrative & support | 2024 |
| BCN Events Ltd | Administrative & support | 2022 |
| BDI Security & Electrical Limited | Administrative & support | 2005 |
| BDM Coaching Limited | Health & social care | 2020 |
| Beama Education C.I.C. | Education | 2016 |
| Beespoke Solutions Limited | Information & communication | 2019 |
| Bekso Ltd | Information & communication | 2013 |
| BEL Global Ltd | Real estate | 2025 |
| Belfast 9046 Limited | Health & social care | 2025 |
| Belfast Accomodation Ltd | Real estate | 2025 |
| Belfast Boiler Installations Ltd | Construction | 2021 |
| Belfast BOY Investments Limited | Real estate | 2020 |
| Belfast BUS & Coach Company Ltd | Transport & logistics | 2012 |
| Belfast BUS Hire Ltd | Transport & logistics | 2012 |
| Belfast BUS Tours Ltd | Transport & logistics | 2012 |
| Belfast Coach Hire Ltd | Transport & logistics | 2012 |
| Belfast Commercial Services Ltd | Wholesale & retail | 2020 |
| Belfast Computer Repairs Ltd | Other services | 2026 |
| Belfast Cooling Specialists Ltd | Construction | 2024 |
| Belfast Dog Groomers Limited | Wholesale & retail | 2020 |
| Belfast Eagles Rlfc Ltd | Arts & recreation | 2022 |
| Belfast Electrical Services Ltd | Manufacturing | 2025 |
| Belfast Foiling Co Ltd | Manufacturing | 2012 |
| Belfast Heating Ltd | Construction | 2019 |
| Belfast Holiday Lets Management Ltd | Real estate | 2026 |
| Belfast Mini Coach Company Limited | Transport & logistics | 2013 |