| Altamuskin Community Association Limited | Other services | 1996 |
| Altro Construction Limited | Real estate | 2004 |
| AMB Wind Farm Ltd | Agriculture & fishing | 2025 |
| AMC International Transport Limited | Transport & logistics | 2018 |
| Amcc Trading Limited | Hospitality | 2019 |
| Amcg Mechanical Services Limited | Construction | 2005 |
| Amck Clinical Psychology Services Limited | Health & social care | 2017 |
| Amco Supplies Ltd | Wholesale & retail | 2014 |
| AMD Hold Co Ltd | Financial services | 2021 |
| AMD Management Ltd | Households | 2021 |
| AMD Property Holdings Limited | Construction | 2015 |
| Amigo Pizza Ltd | Hospitality | 2022 |
| AN Pháirc NUA Limited | Arts & recreation | 2025 |
| Anamore Contract Services Ltd | Construction | 2023 |
| Anamore Ltd | Construction | 2014 |
| Ancs Property Limited | Real estate | 2016 |
| Andon Advisory Ltd | Professional & scientific | 2019 |
| ANF Surveying Ltd | Professional & scientific | 2024 |
| Annalee Holdings Ltd | Financial services | 2023 |
| Annard International Limited | Manufacturing | 2019 |
| Anupro Ltd | Agriculture & fishing | 2020 |
| AOA Ltd | Real estate | 2025 |
| Apollo Professional Ltd | Information & communication | 2024 |
| Apple Blossom Contracts & Utilities Limited | Construction | 2021 |
| Araby Limited | Professional & scientific | 2018 |
| ARC Auto Electrics Omagh Ltd | Manufacturing | 2015 |
| ARC Construction (Omagh) Ltd | Construction | 2016 |
| ARC TQ LLP | | 2010 |
| Arcturus Properties Limited | Households | 2022 |
| Ardaragh Limited | Construction | 2023 |
| Ardmore IT Ltd | Information & communication | 2022 |
| Ardstraw Energy Ltd | Energy | 2024 |
| Aretos Systems Ltd | Professional & scientific | 2026 |
| Arif Trading Limited | Hospitality | 2020 |
| Arkinson Mortgage & Investment Solutions Ltd | Professional & scientific | 2013 |
| Armstrong Funeral Directors & Memorials Ltd | Other services | 2021 |
| Armstrong Rentals Limited | Other services | 2015 |
| Arnie Clements Contracting Ltd | Administrative & support | 2025 |
| Arthur G Investments Limited | Real estate | 2017 |
| Ashfort Properties Ltd | Construction | 2015 |
| Ashleigh (N.I.) Ltd | Construction | 2000 |
| Ashthetics Tyrone Ltd | Extraterritorial | 2023 |
| Asian Curries Limited | Hospitality | 2016 |
| ASJ Poultry Ltd | Agriculture & fishing | 2025 |
| Aspire-Construct Ventures UK Limited | Construction | 2026 |
| Asset Property Investments Ltd | Construction | 2015 |
| Asystec N I Limited | Information & communication | 2014 |
| Atlantic Design and Build Ltd | Construction | 2012 |
| Atlantico Limited | Information & communication | 2013 |
| Atmac Construction Ltd | Construction | 2016 |
| Attavanish Limited | Professional & scientific | 2012 |
| Aughnaglea Energy Limited | Energy | 2015 |
| Authentic Community Services Ltd | Administrative & support | 2025 |
| AWF Poultry Limited | Agriculture & fishing | 2014 |
| Aygo Maintenance Ltd | Construction | 2025 |
| B & D Holdings Ireland Ltd | Financial services | 2021 |
| B & D Investment Properties (Tyrone) Ltd | Real estate | 2023 |
| B Boyle Electrics Ltd | Energy | 2023 |
| B MCG Contracts Limited | Financial services | 2024 |
| B Mindfulness C.I.C. | Other services | 2021 |
| B.E.E.E.D PVC Systems Ltd | Manufacturing | 2017 |
| B.G.I. (NI) | Wholesale & retail | 2005 |
| Badoney Development Partnership | Other services | 2015 |
| Bake Larne Ltd | Manufacturing | 2026 |
| Ballinamullan Auto Ltd | Wholesale & retail | 2019 |
| Ballygawley Management Company Limited | Households | 2014 |
| Ballyhi Construction Ltd | Construction | 2015 |
| Ballymore Fitout Limited | Construction | 2019 |
| Ballymore Roofing and Facades Limited | Construction | 2019 |
| Ballynahatty Properties Limited | Construction | 2014 |
| Ballyutoag Wind Farm Ltd | Energy | 2014 |
| Baltimore Partnership Ltd | Administrative & support | 2013 |
| BAM Holdings Ltd | Real estate | 2015 |
| Bamac Services Ltd | Construction | 2018 |
| Bankmore Mews Management Company Ltd | Households | 2019 |
| Bankmore Properties Limited | Real estate | 1994 |
| Bankmore Rentals Ltd | Construction | 2025 |
| Bann Side Foods Ltd | Manufacturing | 2021 |
| Bannon Electrical Ltd | Construction | 2026 |
| Baoping Jinggg Ltd | Wholesale & retail | 2025 |
| Barford Equipment Ltd | Manufacturing | 2017 |
| Barley Hill 128 Limited | Households | 2025 |
| Barnasone Renewable Energy Ltd | Real estate | 2016 |
| Baronagh Ltd | Energy | 2015 |
| Baronscourt Brewing Company Ltd | Manufacturing | 2018 |
| Barony Services Ltd | Transport & logistics | 2018 |
| Barrett Agriculture Limited | Agriculture & fishing | 2022 |
| Barrett Contracts Ltd | Construction | 2016 |
| Barrett Electrical Contracts Limited | Real estate | 1976 |
| Barron Wind Limited | Energy | 2017 |
| Bath Bubble Omagh Ltd | Wholesale & retail | 2025 |
| Bath Doctor Marine Limited | Manufacturing | 2019 |
| Baxter Waste Solutions (NI) Ltd | Water & waste | 2013 |
| Bayswater Construction Limited | Construction | 2010 |
| BBR Leasing Limited | Administrative & support | 2019 |
| BCC Termon Ltd | Wholesale & retail | 2019 |
| BD Civils Ltd | Construction | 2018 |
| BD Contracts Ltd | Agriculture & fishing | 2015 |
| BD Earthworks Ltd | Construction | 2018 |
| BD Energy Ltd | Energy | 2018 |