| Greer Trading Consulting Limited | Wholesale & retail | 2024 |
| Grove Construction Group (Property) Ltd | Real estate | 2024 |
| Guiney Delopments Ltd | Construction | 2026 |
| Hand Therapy Services (N.I.) Ltd | Health & social care | 2023 |
| Handleybridge Plumbing & Heating Limited | Wholesale & retail | 2026 |
| Harlo Construction Ltd | Construction | 2021 |
| Hart Resources Ltd | Professional & scientific | 1998 |
| Heffron Developments Limited | Construction | 2020 |
| Heffron Estates Limited | Construction | 2011 |
| Hendersons Contracts Ltd | Construction | 2023 |
| Hillsborough Aesthetics Limited | Health & social care | 2023 |
| Hillsborough Arena Sports Association | Arts & recreation | 2002 |
| Hillsborough Community Centre Limited | Other services | 2002 |
| Hillsborough Dental Practice Limited | Health & social care | 2010 |
| Hillsborough Homes Limited | Construction | 2015 |
| Hillsborough Property Limited | Real estate | 2022 |
| Hillsborough Scout and Community Hall Group | Arts & recreation | 2013 |
| Hillsborough Studios Limited | Information & communication | 2015 |
| Hinch Import Ltd | Wholesale & retail | 2024 |
| Hitzone Global Ltd. | Arts & recreation | 2015 |
| HJS Property Limited | Real estate | 2015 |
| Hlep Ltd | Administrative & support | 2006 |
| Homra Logs Limited | Agriculture & fishing | 2014 |
| Hose Doctor NI Limited | Manufacturing | 2016 |
| HPM Procurement Services Ltd | Extraterritorial | 2023 |
| I AM Beauty Limited | Wholesale & retail | 2025 |
| I&T Mckelvey Ltd | Agriculture & fishing | 2025 |
| I.E.S. Industrial (Ireland) Limited | Wholesale & retail | 1988 |
| Iconic Biscuits Ltd. | Manufacturing | 2017 |
| Inishkeel Properties Limited | Households | 2025 |
| Inquisitio Consulting Limited | Professional & scientific | 2019 |
| Invest in Sport Limited | Real estate | 2014 |
| Ipsum Applied Ltd | Professional & scientific | 2021 |
| Ireland Earth Limited | Administrative & support | 2009 |
| Irish Waterways Limited | Extraterritorial | 1967 |
| J B Greer Properties Limited | Real estate | 2007 |
| J G D (Market Square) Limited | Construction | 2006 |
| J G D (Mossvale) Limited | Construction | 2006 |
| J Geddis Holdings Ltd | Construction | 2010 |
| J&J Venture Group Ltd | Financial services | 2026 |
| J. B. Anderson & Co Limited | Real estate | 1913 |
| J3LLYH34D (NI) Limited | Information & communication | 2025 |
| JAC Forest Ltd. | Information & communication | 2016 |
| Jenkins RLR Limited | Professional & scientific | 2026 |
| Jenny Flanagan Laser Aesthetics Ltd | Other services | 2016 |
| JGC (Fallowfields) Limited | Administrative & support | 2026 |
| JGD (Lagan Mills) Limited | Construction | 2006 |
| JGR Medical Services Limited | Health & social care | 2024 |
| JHJ Agencies Limited | Health & social care | 2015 |
| JHJ Property Group Limited | Real estate | 2025 |
| JMW CA Ltd | Professional & scientific | 2023 |
| JN Catering and Events Ltd | Hospitality | 2020 |
| Jobova Limited | Wholesale & retail | 2016 |
| JOD91 Limited | Real estate | 2025 |
| John Farnan Forensic and Medico-Legal Services Ltd | Health & social care | 2014 |
| John Graham Construction (Healthcare) Limited | Construction | 2016 |
| John Graham Construction Limited | Construction | 1955 |
| John Graham Developments Limited | Construction | 2006 |
| John Graham Holdings Limited | Financial services | 2006 |
| John Graham Property Investments Limited | Real estate | 2006 |
| JRH Harvey & Co Ltd | Manufacturing | 2005 |
| Juggernaut Paintball Ltd | Arts & recreation | 2020 |
| Just (NI) Advice Support Advocacy CIC | Information & communication | 2023 |
| K & M Walker Ltd | Manufacturing | 2012 |
| Karibu Coffee Limited | Hospitality | 2022 |
| Karibu Go Limited | Hospitality | 2024 |
| KB Consultants Ltd | Real estate | 2021 |
| Kecese Limited | Information & communication | 2024 |
| Kelvin Graham Limited | Wholesale & retail | 2012 |
| Kentine Enterprises Limited | Financial services | 2010 |
| Kentine Properties Limited | Real estate | 2010 |
| Ketten Feickert NI Limited | Wholesale & retail | 2022 |
| Keys Brothers Horticulture Limited | Manufacturing | 2013 |
| Killowen Management Company Limited | Households | 1984 |
| Kilwarlin Farms Limited | Agriculture & fishing | 2023 |
| Kindred of Ireland Ltd. | Wholesale & retail | 2020 |
| KM Surveying Services Limited | Professional & scientific | 2024 |
| L.C.I. Construction Limited | Construction | 1985 |
| Lagan Valley Steels Limited | Wholesale & retail | 1976 |
| Lakeland Security Services Ltd | Administrative & support | 2021 |
| Lakeside Lettings Hillsborough Ltd | Hospitality | 2021 |
| Law Transport Services Limited | Transport & logistics | 2008 |
| LC Homes Ltd | Construction | 2000 |
| Le-Keys Management Ltd | Real estate | 2024 |
| Lean Logistics Ireland Limited | Transport & logistics | 2016 |
| Leber Medical Ltd | Health & social care | 2019 |
| Lesmar Properties Limited | Real estate | 2002 |
| Lexmor Group Limited | Wholesale & retail | 2023 |
| Limq Ltd | Financial services | 2023 |
| Little DEL Toro Ltd | Hospitality | 2024 |
| Little Explorers( NI) Limited | Health & social care | 2015 |
| Livestock and Machinery Brokers Limited | Wholesale & retail | 2025 |
| LMR Maintenance Limited | Manufacturing | 2023 |
| LMR Modular Limited | Manufacturing | 2023 |
| Londinio Limited | Information & communication | 2011 |
| Lougherne Stud Ltd | Agriculture & fishing | 2009 |
| LOW Cost Self Storage N.I Ltd | Transport & logistics | 2024 |
| Lyons Karting Ltd | Arts & recreation | 2014 |
| M & J Murray Consultants Limited | Professional & scientific | 2016 |
| M G Kennedy Properties Ltd | Construction | 2013 |