| Amad Projects Limited | Hospitality | 2022 |
| Amadan Ensemble | Arts & recreation | 2018 |
| Amadikachi Ltd | Health & social care | 2026 |
| Amaebi Care Services Ltd | Health & social care | 2021 |
| Amalgamated Environmental Services (AES) Limited | Other services | 1992 |
| Amanda Jane Limited | Wholesale & retail | 2024 |
| Amangbo Health Limited | Health & social care | 2022 |
| Amanton Industries LP | | 2018 |
| Amaravathi Belfast Ltd | Hospitality | 2025 |
| Amatissimo Bridal Couture Limited | Wholesale & retail | 2019 |
| Amax Holdings Limited | Construction | 2017 |
| Amazing Brains N. Ireland CIC | Education | 2011 |
| Amber Green Victus (Dufless) Limited | Energy | 2020 |
| Amber House (NI Holdings) Limited | Wholesale & retail | 2021 |
| Amber Merchants Limited | Water & waste | 2003 |
| Amber Support Solutions Ltd | Administrative & support | 2010 |
| Ambergreen Victus Limited | Construction | 2015 |
| Amberstone Events Ltd | Wholesale & retail | 2023 |
| Ambertail Games Ltd | Information & communication | 2020 |
| Ambience Property Management Limited | Real estate | 2018 |
| Ambience Restaurants Ltd | Hospitality | 2018 |
| Ambit CRE Ltd | Real estate | 2014 |
| Ambit Property Management Ltd | Real estate | 1967 |
| Ambleside Todd's Hill Management Ltd | Households | 2014 |
| Ambriel Ltd | Administrative & support | 2018 |
| AMC Surgical Limited | Health & social care | 2024 |
| Amcc Investments Ltd | Real estate | 2018 |
| Amck Investments Limited | Financial services | 2021 |
| Amcm Motors Limited | Wholesale & retail | 2019 |
| Amco Developments Ltd | Construction | 2021 |
| Amco Textiles Limited | Wholesale & retail | 2021 |
| Ameac Ltd | Real estate | 2025 |
| Amelia & Banee Limited | Hospitality | 2018 |
| Amelia Babette Crook Ltd | Wholesale & retail | 2024 |
| Amelias Kitchen Blackstaff Ltd | Hospitality | 2024 |
| Amelio Utilities Holdings Limited | Construction | 2024 |
| Amelio Utilities Limited | Construction | 2013 |
| Amelwood Limited | Real estate | 1985 |
| Amental XIN Ltd | Wholesale & retail | 2024 |
| Amera Aven Limited | Wholesale & retail | 2025 |
| American Nail & Spa Limited | Other services | 2025 |
| Ames Pro Ltd | Wholesale & retail | 2024 |
| Amet Group Holdings Ltd | Financial services | 2019 |
| Amet Insurance Solutions Limited | Financial services | 2016 |
| Amethyst JL LP | | 2021 |
| Amethyst JL Ltd | Financial services | 2021 |
| Amey Roads NI Financial PLC | Administrative & support | 2007 |
| Amey Roads NI Holdings Limited | Financial services | 2007 |
| Amey Roads NI Limited | Transport & logistics | 2007 |
| AMF Construction Solutions Ltd | Administrative & support | 2022 |
| AMF NI Holdings Unlimited | Financial services | 2024 |
| Amfat Ltd | Wholesale & retail | 2025 |
| AMG Insurance Brokers Ltd | Financial services | 2021 |
| Amgi Belfast Limited | Wholesale & retail | 2018 |
| AMH Engineering N.I. Ltd | Manufacturing | 2025 |
| Amigo Developments Limited | Construction | 2017 |
| Amigos Property Limited | Households | 2022 |
| Amina GOODSTYLE1 Ltd | Manufacturing | 2026 |
| Amira Barber & Beauty Centre Ltd | Wholesale & retail | 2025 |
| Amiri Services Limited | Wholesale & retail | 2024 |
| Amita Worldwide Limited | Administrative & support | 2024 |
| AMJ Enterprises and Distributors Limited | Wholesale & retail | 2025 |
| Amjam Limited | Information & communication | 2002 |
| Amlo Diagnostics Ltd | Health & social care | 2013 |
| AMM Productions Limited | Information & communication | 2019 |
| AMM Technologies Limited | Information & communication | 2025 |
| Ammi Systems Limited | Information & communication | 2016 |
| Ammora Limited | Real estate | 2016 |
| AMN Posting Ltd | Other services | 2014 |
| Amnis Auditing Intelligence Ltd | Information & communication | 2024 |
| Amofa LIX Limited | Wholesale & retail | 2024 |
| Amogram Limited | Information & communication | 2016 |
| Amora Properties Limited | Real estate | 2005 |
| Amour Bakar Ltd | Wholesale & retail | 2024 |
| AMP Fusion Limited | Construction | 2020 |
| Amperia Limited | Information & communication | 2012 |
| Amphion Semiconductor Ltd | Information & communication | 2022 |
| Ampion Limited | Professional & scientific | 2011 |
| Amplifi Talent Ltd | Administrative & support | 2020 |
| Amplified Media Agency Limited | Professional & scientific | 2023 |
| Amplify Business Consultants Limited | Professional & scientific | 2012 |
| Amplify Property Solutions Ltd | Real estate | 2021 |
| Ampliphae Ltd | Information & communication | 2014 |
| Amplir Limited | Information & communication | 2025 |
| Amply Discovery Limited | Professional & scientific | 2021 |
| Ampm Food Solutions Ltd | Hospitality | 2021 |
| Ampm Luxury Goods Ltd | Wholesale & retail | 2020 |
| Amrl Services Ltd | Administrative & support | 2025 |
| AMS Capital Ltd | Construction | 2003 |
| Amsor Limited | Wholesale & retail | 2022 |
| Amstal Developments Limited | Real estate | 2018 |
| Amstermed UK Ltd | Professional & scientific | 2021 |
| AMT Wireless Limited | Wholesale & retail | 2023 |
| Amusement Sales & Service Ltd | Manufacturing | 1999 |
| AMY Abbott Limited | Wholesale & retail | 2024 |
| Amyndrew Limited | Wholesale & retail | 2026 |
| AN an Beauty Limited | Wholesale & retail | 2025 |
| AN Droichead Limited | Arts & recreation | 1998 |
| AN Independent Mortgage Solution Ltd | Financial services | 2012 |
| AN Phalaistín Limited | Health & social care | 2024 |