| Airmid Medical Ltd | Wholesale & retail | 2024 |
| Airmount Beauty UK Limited | Wholesale & retail | 2021 |
| Airmount Limited | Real estate | 2002 |
| Airota Limited | Extraterritorial | 2017 |
| Airporter Limited | Transport & logistics | 1997 |
| Airpos Limited | Information & communication | 2009 |
| Airtech Distribution Ltd | Manufacturing | 2007 |
| Aisha Adil Limited | Hospitality | 2022 |
| Aisha PVT Limited | Hospitality | 2019 |
| Aisling Care Services Ltd | Health & social care | 2012 |
| Aisling Daycare & Afterschools Limited | Health & social care | 2014 |
| Aisling Events Limited | Other services | 2013 |
| Aisling Productions Limited | Information & communication | 2015 |
| Aisling School of Irish Dance Limited | Extraterritorial | 2022 |
| AIT Construction Services Limited | Construction | 2014 |
| Aiwawcd Ltd | Wholesale & retail | 2024 |
| Aiyuan Zhang Ltd | Wholesale & retail | 2023 |
| AIZ London Limited | Wholesale & retail | 2025 |
| AJ Admin.Com Ltd | Administrative & support | 2016 |
| AJ Cleaning Team Ltd | Administrative & support | 2021 |
| AJ Creativity PTY Ltd | Wholesale & retail | 2025 |
| AJ Retake Limited | Information & communication | 2022 |
| Aj&P Ltd | Health & social care | 2019 |
| AJC Crystals Ltd | Wholesale & retail | 2021 |
| AJC Dance Designs Ltd | Manufacturing | 2018 |
| AJC Dance Holdings Ltd | Financial services | 2023 |
| AJC Darts Ltd | Wholesale & retail | 2024 |
| AJC Property Rentals Ltd | Real estate | 2023 |
| Ajcl Events Ltd | Hospitality | 2021 |
| AJD 77 Ltd | Financial services | 2024 |
| AJD Motor Repair UK Ltd | Wholesale & retail | 2026 |
| Ajdkaji Ltd | Wholesale & retail | 2025 |
| AJE Property Investment Ltd | Real estate | 2021 |
| Ajfullergroup Limited | Real estate | 2025 |
| Ajhzr Properties Ltd | Real estate | 2024 |
| AJL Produce Limited | Agriculture & fishing | 2019 |
| Ajls Holdings Ltd | Financial services | 2024 |
| AJM Plumbing & Heating NI Limited | Construction | 2020 |
| AJM Sound Limited | Information & communication | 2009 |
| Ajor Ltd | Real estate | 2020 |
| AJS Construction Services Ltd | Construction | 2019 |
| AJS Contracts Ltd | Manufacturing | 2024 |
| AJS Solutions Ltd | Administrative & support | 2022 |
| AJS Workwear & Graphics Limited | Wholesale & retail | 2023 |
| AK Building Contracts Limited | Construction | 2026 |
| AK Car Wash Limited | Other services | 2017 |
| AK ENT Holdings Ltd | Financial services | 2026 |
| AK ENT Ltd | Health & social care | 2020 |
| AK Imports & Exports Ltd | Wholesale & retail | 2026 |
| AK Sonics Ltd | Wholesale & retail | 2025 |
| Akdni Ltd | Wholesale & retail | 2024 |
| Akintoglass Ltd | Wholesale & retail | 2025 |
| AKL Energy Ltd | Wholesale & retail | 2021 |
| AKL Mortgages Ltd | Financial services | 2024 |
| AKM Construction Ltd | Construction | 2013 |
| AKM Investments Ltd | Real estate | 2019 |
| Akmc Investments Ltd | Financial services | 2024 |
| Aksyso Co., Ltd | Wholesale & retail | 2025 |
| Aktivora (N.I.) Limited | Wholesale & retail | 2020 |
| AKU Training Ltd | Professional & scientific | 2014 |
| AKV Energy Ltd | Energy | 2014 |
| AL Aziz Ltd | Hospitality | 2018 |
| AL Gelato Limited | Wholesale & retail | 2017 |
| AL Hassan Brothers Ltd | Hospitality | 2026 |
| AL Shahba Bakery Limited | Wholesale & retail | 2022 |
| Al-Bayt Housing Limited | Construction | 2022 |
| Al-Ummah Northern Ireland CIC | Health & social care | 2025 |
| Alabon Limited | Real estate | 2016 |
| Alaepow Technology Limited | Wholesale & retail | 2026 |
| Alaia Ltd | Health & social care | 2024 |
| Alam Collection Limited | Wholesale & retail | 2025 |
| Alan Bennett Architects Ltd | Extraterritorial | 2009 |
| Alan Cahoon Enterprises Limited | Construction | 2017 |
| Alan Campbell Ltd | Wholesale & retail | 2025 |
| Alan Campbella Ltd | Wholesale & retail | 2025 |
| Alan Clarke Joinery Works Limited | Construction | 2002 |
| Alan Kurdi Ltd | Other services | 2025 |
| Alan Lester Limited | Wholesale & retail | 2025 |
| Alan Lewis Displays Limited | Administrative & support | 1991 |
| Alan Martin Design Ltd | Professional & scientific | 2016 |
| Alan Mcveigh Motor Repairs Limited | Wholesale & retail | 2011 |
| Alan Michael Limited | Manufacturing | 2024 |
| Alandale Management (Bangor) Limited | Households | 2001 |
| Alar Transport Ltd | Transport & logistics | 2025 |
| Alas Property Ltd | Real estate | 2025 |
| Alastair Coey Architects Ltd | Professional & scientific | 2010 |
| Alay's Bio-Innovations Ltd | Manufacturing | 2026 |
| Alayam Properties Limited | Real estate | 2025 |
| ALB Hand Car Wash Ltd | Wholesale & retail | 2020 |
| Albany Products N.I. Limited | Wholesale & retail | 2022 |
| Albemarle Residential Limited | Real estate | 2015 |
| Albert ADU Limited | Wholesale & retail | 2024 |
| Albert Antenbrink Limited | Wholesale & retail | 2025 |
| Albertbridge Car Wash Ltd | Wholesale & retail | 2026 |
| Albertbridge Road Two Management Company Limited | Households | 2008 |
| Albion Kebab Ltd | Wholesale & retail | 2025 |
| Albion Real Estate Ltd | Professional & scientific | 2019 |
| Alcamp Limited | Extraterritorial | 2016 |
| Alchemy Diamonds Ltd | Manufacturing | 2022 |
| Alchemy Distil Ltd | Manufacturing | 2018 |