| 12 Sea Limited | Financial services | 2023 |
| 145 C.I.C. | Arts & recreation | 2016 |
| 2 Castles Coffee Limited | Wholesale & retail | 2023 |
| 21A Architecture Ltd | Professional & scientific | 2024 |
| 2A Intelligence Solutions Limited | Wholesale & retail | 2024 |
| 3LOD Risk Management Services Limited | Professional & scientific | 2015 |
| 442 Apparel Ltd | Manufacturing | 2022 |
| 5 Mornington Management Company Limited | Households | 2021 |
| 50 CAL Trading Ltd | Wholesale & retail | 2026 |
| 57 Leisure Parks Limited | Hospitality | 1998 |
| 7 Tower Lane Ltd | Construction | 2026 |
| 73 Dufferin Avenue Management Company Limited | Households | 2019 |
| 7TH Heaven Cafe Ards Limited | Hospitality | 2024 |
| @Killinchycabins Ltd | Households | 2024 |
| A Cromie Limited | Construction | 2026 |
| A F White Manufacturers Limited | Manufacturing | 2015 |
| A Mccauley Limited | Construction | 2014 |
| A P B Medical ( N I ) Limited | Health & social care | 2020 |
| A Slice of Heaven Ltd | Manufacturing | 2011 |
| A Turkington Bricklaying Ltd | Construction | 2013 |
| A W Solutions (NI) Ltd | Professional & scientific | 2014 |
| A&J Scaffolding Services Limited | Construction | 2024 |
| A.N.E. Hamilton Ltd | Real estate | 2025 |
| Aa&G Access Ltd | Construction | 2025 |
| Abacus Sigma Limited | Real estate | 1993 |
| Abbey Guns Ltd | Wholesale & retail | 2026 |
| Abbey Road Developments Millisle Ltd | Construction | 2021 |
| Abcd Education Group Limited | Wholesale & retail | 2025 |
| Abijidanderetail Ltd | Wholesale & retail | 2024 |
| ABM Money Ltd | Financial services | 2025 |
| Accident Assist Automotive Ltd | Wholesale & retail | 2010 |
| ACCOUNTS4LESS Limited | Professional & scientific | 2005 |
| Ace Facilities Management Limited | Water & waste | 2016 |
| ACF Trading Limited | Wholesale & retail | 2019 |
| Across the Nations Limited | Extraterritorial | 1994 |
| Action Mental Health | Administrative & support | 1963 |
| Actively Transforming Youth & Community | Other services | 2015 |
| Adam Mccord Ltd | Wholesale & retail | 2024 |
| Adcentail Joiek Ltd | Wholesale & retail | 2025 |
| Adfinnovative Limited | Wholesale & retail | 2026 |
| Admac CS Ltd | Professional & scientific | 2022 |
| Adol Limited | Wholesale & retail | 2010 |
| Adult Adhd Care Ltd | Health & social care | 2022 |
| Aearis Property Ltd | Households | 2025 |
| AEB Care Ltd | Health & social care | 2014 |
| AED Metal Cutting Services Ltd | Manufacturing | 2011 |
| Aequus Belfast Ltd | Extraterritorial | 2013 |
| AER Energy Limited | Manufacturing | 2019 |
| AEV Consulting Ltd | Wholesale & retail | 2007 |
| African-Diplomatic-Supply Ltd | Manufacturing | 2024 |
| AG Electrical (NI) Ltd | Other services | 2014 |
| Again App Ltd | Wholesale & retail | 2026 |
| Agar Murdoch & Deane Limited | Real estate | 2005 |
| AGM Belfast Ltd | Wholesale & retail | 2012 |
| Ahmad Zone Limited | Other services | 2024 |
| Ahmet Tayyip Kalbur Ltd | Wholesale & retail | 2024 |
| AHR Property Maintenance Ltd | Construction | 2023 |
| Ailisikylebeide Limited | Wholesale & retail | 2025 |
| AIM GW Ltd | Wholesale & retail | 2023 |
| Airproful Ltd | Wholesale & retail | 2025 |
| AJ Farms Limited | Agriculture & fishing | 2017 |
| AJC Enterprises (Portavogie) Ltd | Agriculture & fishing | 2026 |
| AJC Mclernon Limited | Real estate | 2025 |
| ALA Property Partners Limited | Financial services | 2025 |
| Alderwood Developments Limited | Financial services | 2004 |
| Aleksandra Pasternack Ltd | Wholesale & retail | 2024 |
| Alethea Limited | Wholesale & retail | 2025 |
| Alexander Cairnduff & Sons Limited | Construction | 1966 |
| Alexander Law Fibreglass (N.I.) Limited | Extraterritorial | 1975 |
| Alister Fenton Ltd | Wholesale & retail | 2025 |
| ALL Seasons Ground Maintenance Ltd | Other services | 2026 |
| ALL Things Counselling for Schools Ltd | Health & social care | 2024 |
| Allan Nelson Ltd | Wholesale & retail | 2025 |
| Alliamot Limited | Wholesale & retail | 2025 |
| Allmilmo Ltd | Wholesale & retail | 2024 |
| Alpha Design Telecoms Services Ltd | Information & communication | 2019 |
| Alpha Mews Management Limited | Real estate | 2002 |
| Alpha Stag Ltd | Information & communication | 2025 |
| Alphass Logistics Ltd | Wholesale & retail | 2024 |
| ALS Associated NI Limited | Wholesale & retail | 2022 |
| Alsace FR Ltd | Other services | 2025 |
| Altinbas ALI Limited | Wholesale & retail | 2025 |
| Altitude Films Ltd | Information & communication | 2026 |
| AM Elite Contracts Ltd | Construction | 2022 |
| Amaal ABD Limited | Wholesale & retail | 2025 |
| Ambition Healthcare Ltd | Health & social care | 2019 |
| Ambleside Corner Limited | Information & communication | 2022 |
| Ambleside Property Holdings Limited | Professional & scientific | 2021 |
| Amplify Sales & Marketing Limited | Administrative & support | 2023 |
| Ampup Ltd | Energy | 2025 |
| AMR Exterior Cleaning and Pressure Washing Limited | Administrative & support | 2024 |
| AMR Window Cleaning Ltd | Administrative & support | 2026 |
| AMY and Elizabeth Limited | Wholesale & retail | 2024 |
| AMY Pro 11 Limited | Wholesale & retail | 2024 |
| Andboy Limited | Real estate | 2012 |
| Anderhey Trade Limited | Wholesale & retail | 2025 |
| Anderson Wealth Planning Ltd. | Financial services | 2013 |
| Andrew Feliks Jackson Ltd | Wholesale & retail | 2025 |
| Andrew Morris Golf Limited | Wholesale & retail | 2012 |
| Andrew NEY Limited | Wholesale & retail | 2024 |