| High ST Property Limited | Real estate | 2014 |
| High Wire Property Limited | Real estate | 2017 |
| Hill Automotives Ltd | Wholesale & retail | 2024 |
| Hill Renewables Limited | Energy | 2011 |
| Hillcook Limited | Construction | 2024 |
| Hillmount Management Limited | Administrative & support | 2016 |
| Hilltop Storage Loughgall Ltd | Transport & logistics | 2021 |
| Hilltown Development Ltd | Construction | 2024 |
| HK Retail Investments Ltd | Wholesale & retail | 2020 |
| Hmck Enterprises Limited | Real estate | 2013 |
| HN Builders Ltd | Construction | 2017 |
| Hole Ltd | Construction | 2020 |
| Hollow Farm (NI) Ltd | Agriculture & fishing | 2021 |
| Holmes & Doran Ltd | Professional & scientific | 2005 |
| Home at Frazers Ltd | Wholesale & retail | 2021 |
| Home Value Limited | Extraterritorial | 2008 |
| Homecare Housing Limited | Hospitality | 2019 |
| Homecare Support Services Limited | Health & social care | 2005 |
| Hope Cares (Craigavon) Ltd | Education | 2017 |
| House of Hurson Ltd | Wholesale & retail | 2024 |
| Houseproud Media UK Ltd | Professional & scientific | 2019 |
| Howard Packaging 2014 Limited | Manufacturing | 2014 |
| HR & Finance Solutions Ltd | Professional & scientific | 2016 |
| Hsse Compliance Solutions Ltd | Professional & scientific | 2017 |
| Hugge Design Limited | Wholesale & retail | 2021 |
| Hugh Mccann Contracts Ltd | Construction | 2015 |
| Hughes Agri Ltd | Agriculture & fishing | 2020 |
| Hughes Autoparts Ltd | Wholesale & retail | 2024 |
| Hughes Haulage (NI) Ltd | Transport & logistics | 2013 |
| Hughes Hvac Ltd | Construction | 2026 |
| Hughes Mortgage Centre (NI) Ltd | Financial services | 2015 |
| Hughes Power and Civils Ltd | Construction | 2026 |
| Hughes Surfacing and Groundworks Ltd | Construction | 2021 |
| Humark Ltd | Administrative & support | 2021 |
| Husean Ltd | Administrative & support | 2021 |
| Ifkk Limited | Hospitality | 2025 |
| Ikerr Ltd | Wholesale & retail | 2025 |
| Imemo Ltd | Information & communication | 2023 |
| Imex Direct Ltd | Wholesale & retail | 2020 |
| IMT Farms Ltd | Agriculture & fishing | 2024 |
| Incredable | Health & social care | 2007 |
| Indiwoods Limited | Agriculture & fishing | 2007 |
| Info Forte Limited | Information & communication | 2020 |
| Innasmat Limited | Financial services | 2007 |
| Innovating Interiors Ireland Ltd | Professional & scientific | 2021 |
| Innovative Home Solutions Ltd | Construction | 2014 |
| Innovision Trans Limited | Extraterritorial | 2016 |
| Instant Print (NI) Ltd | Manufacturing | 2010 |
| Interbev Ireland Ltd. | Hospitality | 2002 |
| Interrailingpackages Limited | Administrative & support | 2015 |
| Invisi Wellness Ltd | Manufacturing | 2026 |
| IPS Co Armagh Limited | Professional & scientific | 2025 |
| Irish Draught Horse Society Limited | Other services | 2009 |
| Irish Hemp Ltd | Agriculture & fishing | 2021 |
| Iron Designs (Armagh) Limited | Manufacturing | 2004 |
| Ironroot Construction & Property Limited | Construction | 2026 |
| ISD Transport NI Ltd | Transport & logistics | 2025 |
| Isis Planning Solutions Limited | Information & communication | 2014 |
| Iskoni Trans Limited | Wholesale & retail | 2026 |
| Isobel Anderson Music Limited | Information & communication | 2017 |
| Isopipe Solutions Limited | Construction | 2015 |
| IT Hub Armagh NI Ltd | Information & communication | 2017 |
| IV Health Lounge Ltd | Other services | 2024 |
| IWC Estates Limited | Real estate | 1990 |
| J a Poultry Limited | Agriculture & fishing | 2018 |
| J Crilly Consultancy Ltd | Professional & scientific | 2025 |
| J E Scott & Sons (NI) Limited | Administrative & support | 2003 |
| J G C (Armagh) Limited | Other services | 2007 |
| J J Haughey Solicitors Ltd | Professional & scientific | 2012 |
| J Mcnamara Holdings Ltd | Manufacturing | 2026 |
| J O'Neill Psychiatry Limited | Health & social care | 2023 |
| J P Trailers Limited | Wholesale & retail | 2016 |
| J Shortt Recycling Ltd | Wholesale & retail | 2011 |
| J&P Hire Ltd | Construction | 2023 |
| J. J. Taylor & Co Solicitors Ltd | Professional & scientific | 2020 |
| J.J. Mcardle & Sons Ltd | Other services | 2014 |
| J.P. Murphy Limited | Construction | 2003 |
| J.S. Property Solutions (N.I.) Limited | Real estate | 2025 |
| Jackson Haulage Ltd | Transport & logistics | 2014 |
| James Johnston Limited | Manufacturing | 2016 |
| James Stewart & Sons (Clocks) Limited | Manufacturing | 2003 |
| James Zwecker Transport & Storage Ltd | Transport & logistics | 2012 |
| Jamson Trading Limited | Wholesale & retail | 2017 |
| Japples Limited | Wholesale & retail | 2020 |
| Jarlath Fields Solicitors Ltd | Professional & scientific | 2017 |
| JB Livestock Limited | Agriculture & fishing | 2023 |
| JB Property Uk-Irl Limited | Real estate | 2007 |
| JB Timber Products & Building Supplies Ltd | Manufacturing | 2018 |
| Jbm-Barry Murphy & Co Limited | Professional & scientific | 2025 |
| JBT Mechanical Services Limited | Construction | 2017 |
| JD Livestock & Equine Ltd | Transport & logistics | 2025 |
| JDR Motors Limited | Wholesale & retail | 2017 |
| Jdsw International Ltd | Public administration | 2025 |
| JED Electrical Contracts Ltd | Construction | 2019 |
| Jega Investments Limited | Financial services | 2024 |
| JEM Quality Ltd | Professional & scientific | 2024 |
| Jenna's Food Ltd | Hospitality | 2015 |
| JF Mckenna (Holdings) Limited | Financial services | 2021 |
| JFB Engineering | Manufacturing | 2011 |
| JFL Group Limited | Wholesale & retail | 2023 |