| HI - Performance Equipment Ltd | Manufacturing | 2025 |
| HI Performance Boxing Ltd | Arts & recreation | 2024 |
| HI Performance Training Ltd | Arts & recreation | 2020 |
| Hi-Trump Tech Limited | Wholesale & retail | 2025 |
| Hibernia Atlantic (NI) Limited | Information & communication | 1971 |
| Hibernica Ltd | Administrative & support | 2024 |
| Hibeyica Ltd | Other services | 2025 |
| Hiddeneyeni Limited | Administrative & support | 2022 |
| Hidowne Finance Limited | Construction | 2014 |
| Hifame Ltd | Wholesale & retail | 2025 |
| Higgidy NI Ltd | Manufacturing | 2021 |
| Higgins Mulholland Properties Limited | Real estate | 2021 |
| High Coat Roofing Limited | Construction | 2017 |
| High Five Ents Limited | Arts & recreation | 2015 |
| High Grand Limited | Wholesale & retail | 2024 |
| High Inspiration Group Ltd | Wholesale & retail | 2024 |
| High IT Technologies LP | | 2018 |
| High Phone Ltd | Wholesale & retail | 2024 |
| High Rock Media Northern Ireland Ltd | Information & communication | 2024 |
| High Street Ballymoney Limited | Real estate | 2026 |
| High Street Dental Ballymoney Ltd | Health & social care | 2012 |
| High Street Dental Practice Holywood Ltd | Health & social care | 2020 |
| High Street Investments Limited | | 1991 |
| High Trees Donaghadee Management Company Limited | Households | 2019 |
| Highered-Ai Ltd | Information & communication | 2025 |
| Highgrove Meadows Management Co Ltd | Households | 2016 |
| Highly FLY Limited | Wholesale & retail | 2024 |
| Highport Estate LP | | 2019 |
| Highroads NI Ltd | Information & communication | 2018 |
| Highway Barrier Solutions Limited | Construction | 2008 |
| Highway Management (City) Finance PLC | Financial services | 2005 |
| Highway Management (City) Holding Limited | Financial services | 2005 |
| Highway Management (City) Limited | Financial services | 2005 |
| Highway Plant Co. Limited | Administrative & support | 1983 |
| HIIT2FIT Health and Fitness Ltd | Other services | 2021 |
| Hilberry Ltd | Real estate | 2026 |
| Hilditch Martin Services Limited | Wholesale & retail | 2003 |
| Hill & Hill Properties Limited | Real estate | 2000 |
| Hill Billy Jacks Ltd | Hospitality | 2017 |
| Hill Business Growth Consultants Ltd | Professional & scientific | 2012 |
| Hill Contracts (NI) Limited | Construction | 2010 |
| Hill Hardware Limited | Wholesale & retail | 2024 |
| Hill ST Holdings Limited | Hospitality | 2026 |
| Hill ST Trading Limited | Hospitality | 2026 |
| Hill Street Management Limited | Real estate | 2013 |
| Hill Vellacott LLP | | 2009 |
| Hillbroom Manor Services Limited | Extraterritorial | 1990 |
| Hillcrest Agri Ltd | Wholesale & retail | 2011 |
| Hillfoot Park Management Company Limited | Households | 2009 |
| Hillfoot Street Management Company Limited | Real estate | 2007 |
| Hillgrove Investments Ltd | Real estate | 2020 |
| Hillhall Cafes Limited | Hospitality | 2010 |
| Hillmond Properties Limited | Extraterritorial | 2006 |
| Hillmount Developments (NI) Limited | Construction | 2013 |
| Hills Legacy Services Limited | Professional & scientific | 2025 |
| Hillsborough Cars & Classics Ltd | Wholesale & retail | 2025 |
| Hillsborough Court Management Company (N.I.) Ltd | Extraterritorial | 2000 |
| Hillsborough Development Co. Ltd | Construction | 2023 |
| Hillsborough Manor Management Company Limited | Extraterritorial | 2000 |
| Hillsborough Road Mews Apartments Management Company Limited | Households | 2017 |
| Hillsdown Water Services Limited | Administrative & support | 2008 |
| Hillside Interiors Kilkeel Limited | Manufacturing | 2014 |
| Hilltop Developments (NI) Limited | Construction | 2014 |
| Hilltop Foot and Ankle Ltd | Health & social care | 2011 |
| Hilltop House Farm Ltd | Agriculture & fishing | 2020 |
| Hilltops (Lisburn) Limited | Households | 2019 |
| Hilltree Limited | Professional & scientific | 2026 |
| Hillview Centre Belfast Limited | Real estate | 2015 |
| Hillview Developments (Europe) Limited | Professional & scientific | 2017 |
| Hillview Kitchen Centre Ltd | Manufacturing | 2018 |
| Hilmark Blue Horizon Developments LLP | | 2014 |
| Hilmer (Northern Ireland) Holding Limited | Wholesale & retail | 2016 |
| Hilmer (Northern Ireland) Limited | Wholesale & retail | 2016 |
| Hilmer Bangor Limited | Wholesale & retail | 2018 |
| Hilmer Newry Limited | Wholesale & retail | 2016 |
| Hilton Food Group (Europe) Limited | Extraterritorial | 2002 |
| Hilton Food.Com Limited | Extraterritorial | 2000 |
| Hilton Foods Limited | Professional & scientific | 1998 |
| Hilton Foods UK Limited | Manufacturing | 1992 |
| Hilton Meats Holland Limited | Extraterritorial | 1999 |
| Hinds & Co Solicitors Ltd | Professional & scientific | 2010 |
| Hings Chinese Takeaway Ltd | Hospitality | 2026 |
| Hinkinc Ltd | Real estate | 2021 |
| HIP Psychology Ltd | Professional & scientific | 2023 |
| Hire a MOG Ltd | Extraterritorial | 2022 |
| Hireiq Ltd | Administrative & support | 2019 |
| Histosolutions Ltd | Health & social care | 2022 |
| HIT the North Belfast Ltd | Professional & scientific | 2023 |
| Hitang Co., Ltd | Wholesale & retail | 2023 |
| Hitch Real Life Limited | Arts & recreation | 2021 |
| Hitchen Thermal Insulation Ltd | Manufacturing | 2011 |
| Hitech Assets L.P. | | 2018 |
| Hitw Limited | Hospitality | 2014 |
| Hiveuav Limited | Manufacturing | 2018 |
| Hiya Daily Limited | Wholesale & retail | 2025 |
| Hiyin Limited | Wholesale & retail | 2024 |
| HJD Surgical Limited | Health & social care | 2020 |
| Hjddhnsue Ltd | Wholesale & retail | 2024 |
| HJM Solutions Limited | Other services | 2014 |
| HJR Inc Ltd | Real estate | 2025 |