| Hundred Surface Limited | Wholesale & retail | 2025 |
| Hungri Games UK Limited | Information & communication | 2021 |
| Hungry Cat Promotions Ltd | Hospitality | 2021 |
| Hungry Mummy Limited | Real estate | 2019 |
| HUNGRY2NITE Ltd | Hospitality | 2016 |
| Hunt Medical Services Limited | Professional & scientific | 2012 |
| Hunt Office Technology (UK) Limited | Wholesale & retail | 2010 |
| Hunter Doak Ltd | Information & communication | 2016 |
| Hunter FS Limited | Financial services | 2011 |
| Hunter Paper Co Ltd | Wholesale & retail | 2021 |
| Hunter Savage Group Ltd | Financial services | 2024 |
| Hunter Savage Holdings Ltd | Administrative & support | 2021 |
| Hunterhouse College | Education | 1987 |
| Hunters Mini Coach Travel Ltd | Transport & logistics | 2025 |
| Huntingdale Properties Limited | Households | 1990 |
| Huntingdon Hill Property Management Limited | Households | 2017 |
| Huntington's Disease Association Northern Ireland | Professional & scientific | 2009 |
| Huppyte Ltd | Wholesale & retail | 2024 |
| Huraton Impex LP | | 2017 |
| Hurford Graham Smith Ltd | Manufacturing | 2026 |
| Hurst Travel Limited | Administrative & support | 2012 |
| Hurtletoot Holdings Ltd | Other services | 2023 |
| Hustle Gym Limited | Arts & recreation | 2020 |
| Huston & Co LLP | | 2005 |
| Huston Bros. Ltd | Extraterritorial | 2007 |
| Huston Ltd | Professional & scientific | 2007 |
| Hutchinson Advisory Services Ltd | Professional & scientific | 2026 |
| Hutchinson Print Ltd | Manufacturing | 2014 |
| Hutchison & White Ltd | Financial services | 2008 |
| Hutchman Property Holdings Limited | Real estate | 2024 |
| Hutton Mechanical & Electrical Services Ltd | Construction | 2003 |
| Huttonstorm Holdings Limited | Financial services | 2022 |
| Huttonstorm Limited | Real estate | 2022 |
| Huweiyanhjjgj Ltd | Wholesale & retail | 2023 |
| Huyuy HNG Limited | Wholesale & retail | 2023 |
| Huzasu Ltd | Wholesale & retail | 2025 |
| Huze Dream Limited | Wholesale & retail | 2025 |
| Huziwa PTI Limited | Wholesale & retail | 2023 |
| HV Safety Consultants Ltd | Construction | 2020 |
| Hvmc Limited | Households | 2006 |
| HWD Management Ltd | Households | 2019 |
| Hwpo 1 Limited | Financial services | 2021 |
| Hwptc Ltd | Professional & scientific | 2018 |
| HX Collective Ltd | Other services | 2021 |
| Hybrid Fitness NI Limited | Arts & recreation | 2013 |
| Hybrid Mail Solutions Limited | Transport & logistics | 2011 |
| Hydepark Road Developments Limited | Construction | 2016 |
| Hydrate Apps Ltd | Information & communication | 2024 |
| Hydration Systems Ltd | Information & communication | 2022 |
| Hydrii Solutions Limited | Professional & scientific | 2021 |
| Hydro Power Ireland Limited | Energy | 2014 |
| Hydro Solutions Limited | Administrative & support | 1993 |
| Hydro-Ease Limited | Health & social care | 2015 |
| Hydrogen Green Power Ltd | Manufacturing | 2017 |
| Hydrogen Ireland Limited | Wholesale & retail | 2021 |
| Hydrogen NI Holdings Limited | Other services | 2021 |
| Hydrus Enterprises Limited | Information & communication | 2001 |
| Hygiene Services Ltd | Administrative & support | 2019 |
| Hyland Electrical Services (2025) Ltd | Construction | 2025 |
| Hylands Developments Limited | Construction | 1999 |
| Hylands Fuels (N.I) Limited | Wholesale & retail | 1976 |
| Hylas Limited | Households | 1988 |
| Hypehaus Limited | Wholesale & retail | 2025 |
| Hyper Online Ltd | Professional & scientific | 2023 |
| Hyperduck Soundworks Limited | Information & communication | 2015 |
| Hypership Holdings Limited | Extraterritorial | 2026 |
| Hypership Ltd | Information & communication | 2026 |
| Hypixel Studios Limited | Information & communication | 2020 |
| Hypnotrack Ltd | Other services | 2026 |
| Hystoutechnology Co Limited | Wholesale & retail | 2025 |
| Hyuui Limited | Wholesale & retail | 2024 |
| I AM GIA Limited | Wholesale & retail | 2021 |
| I Film Ltd | Information & communication | 2025 |
| I H Belfast Teacher Training Limited | Education | 2010 |
| I SEE Wonders Limited | Wholesale & retail | 2018 |
| I T T ( NI ) Limited | Manufacturing | 2015 |
| I&E for U Ltd | Administrative & support | 2024 |
| I-Line Continuous Improvement Ltd | Information & communication | 2026 |
| I. S. Projects Co. Ltd. | Construction | 2004 |
| I.T. Alliance N.I. Limited | Information & communication | 1998 |
| I.T. Promotions Ltd | Professional & scientific | 2019 |
| I.T.D.C.S. Ltd | Information & communication | 1999 |
| I1 Technologies Ltd | Information & communication | 2025 |
| I3 Digital Ltd | Information & communication | 2007 |
| I3 Digital Technologies Ltd | Information & communication | 2025 |
| I8I Ltd | Information & communication | 2025 |
| IA Distribution (N.I.) Ltd | Wholesale & retail | 2021 |
| Iaco One Limited | Real estate | 2006 |
| Iaco Three Limited | Real estate | 2006 |
| Iaco Two Limited | Real estate | 2006 |
| Iacono Giuseppe Ltd | Wholesale & retail | 2025 |
| Iakoe Ltd | Information & communication | 2020 |
| IAN Hogg Ltd | Wholesale & retail | 2025 |
| IAN Mccullough Ltd | Professional & scientific | 1999 |
| IAN Mcgowan Cricket Coaching Limited | Arts & recreation | 2019 |
| IAN Mcpherson Limited | Manufacturing | 2024 |
| IAN Pedlow Photography Ltd | Professional & scientific | 2026 |
| IAN Reid Heating Services Ltd | Construction | 2019 |
| Iaso Solutions Ltd | Information & communication | 2025 |
| Iassistni Limited | Health & social care | 2024 |