| Hawk Equipment Ltd | Wholesale & retail | 2025 |
| Hazelgrove Avenue Management Limited | Households | 2013 |
| Hbtk Hair Ltd | Other services | 2012 |
| Hcsni Ltd | Health & social care | 2025 |
| Headington Manor Management Company Limited | Real estate | 2016 |
| Heather Corner Management Company Limited | Households | 2019 |
| Heaven Nails Carrickfergus Ltd | Other services | 2025 |
| Hejip Holdings Limited | Professional & scientific | 2018 |
| Hejip Properties Limited | Real estate | 2020 |
| Helena Steacy Tattoos Ltd | Arts & recreation | 2023 |
| Hendersons Decorators Ltd | Construction | 2016 |
| Henry Transport Solutions Ltd. | Administrative & support | 2018 |
| Hercules Brewing & Co. Limited | Manufacturing | 2012 |
| HERE2HELP App | Health & social care | 2015 |
| Heritage Engineering Ireland Ltd | Manufacturing | 2011 |
| Herlane Limited | Real estate | 1978 |
| Hibernia Care Services Limited | Health & social care | 2025 |
| High DOH Ltd | Information & communication | 2019 |
| Highgrove (Ballymena) Management Company Ltd | Households | 2017 |
| Hill Crest Commercials Ltd | Transport & logistics | 2014 |
| Hillhall Grange Management Company Limited | Households | 2006 |
| Hilton Meat Products Limited | Manufacturing | 1984 |
| Hive Workforce Ltd | Administrative & support | 2023 |
| Hoamz Investments Ltd | Real estate | 2024 |
| Hodaygo Ltd | Wholesale & retail | 2025 |
| Holborn Mews Management Limited | Households | 2002 |
| Holdfast (Funerals) Limited | Extraterritorial | 1973 |
| Holistic ED CIC | Education | 2024 |
| Holly Manor Management Co. Ltd | Extraterritorial | 2003 |
| Holmes Aviation Limited | Manufacturing | 2024 |
| Holywood Deli Ltd | Wholesale & retail | 2021 |
| Home Services N.I Limited | Administrative & support | 2025 |
| Home-Start East Antrim | Health & social care | 2014 |
| House of TAN Carrickfergus Limited | Other services | 2018 |
| HR Contracts Limited | Construction | 2012 |
| HT Mortgages Ltd | Financial services | 2025 |
| Hughes Team Corporation Ltd | Arts & recreation | 2023 |
| Hunter Campbell Estate Agents Ltd | Extraterritorial | 2007 |
| HW (N.I.) Limited | Real estate | 2019 |
| Ibiza TAN Solutions Ltd | Wholesale & retail | 2026 |
| Iconic Arches Ltd | Other services | 2025 |
| Iepoly Ltd | Manufacturing | 2022 |
| Ikon Developments Limited | Construction | 2001 |
| Illicit Temptations Ltd | Other services | 2026 |
| IMAJ72 Ltd | Other services | 2022 |
| Important Mini People Ltd | Health & social care | 2014 |
| IN HR Solutions Limited | Professional & scientific | 2019 |
| Increedible Ltd | Hospitality | 2018 |
| Indian Carickk Limited | Hospitality | 2018 |
| Industrial Precision Components Ltd | Manufacturing | 2008 |
| Industrial Products Limited | Manufacturing | 2000 |
| Industrial Sales Agencies (N.I.) Ltd | | 1987 |
| Infinity Surveys Ltd | Professional & scientific | 2022 |
| Innovate Agencies Ltd | Wholesale & retail | 2018 |
| Innovation Technologies (Ireland) Ltd | Manufacturing | 1998 |
| Insure NI Limited | Professional & scientific | 2002 |
| Integral Products Ltd | Wholesale & retail | 2024 |
| Interior Solution Designs Ltd | | 2003 |
| Irish Salt Mining and Exploration Company Limited-The | Mining & quarrying | 1965 |
| It's Ronan Ltd | Arts & recreation | 2021 |
| Italian Apparel Limited | Wholesale & retail | 2013 |
| Izgut Ltd | Wholesale & retail | 2025 |
| J & E Installation Services Limited | Construction | 2018 |
| J J E Electrical Limited | Construction | 2025 |
| J S Design & Build Ltd | Construction | 2018 |
| J&J Reid Properties Ltd | Real estate | 2022 |
| J&M OOH Media Services Ltd | Professional & scientific | 2021 |
| J.E. Rigging Services Ltd | Construction | 2019 |
| J.H. Mcnickle & Sons Limited | Manufacturing | 1978 |
| Jack Reid Cars Limited | Wholesale & retail | 2008 |
| Jack Reid Service Centre Ltd | Wholesale & retail | 2024 |
| JAD AER Ltd | Manufacturing | 2015 |
| Jade Dynasty Trading Ltd | Wholesale & retail | 2026 |
| Jafes Properties Ltd | Real estate | 2022 |
| James F Mccue Limited | Manufacturing | 1961 |
| Jason Shankey Limited | Wholesale & retail | 2002 |
| Jazzberry Cafe Limited | Hospitality | 2019 |
| JC Ecom Ltd | Wholesale & retail | 2023 |
| JD Hardwood Ltd | Wholesale & retail | 2026 |
| JDS Security NI Ltd | Administrative & support | 2025 |
| Jeanius CK Limited | Wholesale & retail | 2018 |
| Jenbie Limited | Wholesale & retail | 2024 |
| Jete NDT Ltd | Mining & quarrying | 2021 |
| JGG Traders Ltd | Manufacturing | 2025 |
| Jhallelectric Ltd | Construction | 2026 |
| JK Roofing N.I. Ltd | Construction | 2024 |
| Jk's Goods Ltd | Wholesale & retail | 2025 |
| JKS Pizza Ltd | Hospitality | 2021 |
| Jmca Car & Commercial Sales Ltd | Wholesale & retail | 2021 |
| Jmca Commercials Ltd | Transport & logistics | 2021 |
| Jmcf Aviation Ltd | Manufacturing | 2019 |
| JOE Swail Ltd | Arts & recreation | 2011 |
| John Mcvea Advisory Services Ltd | Professional & scientific | 2023 |
| John Mcvea Limited | Real estate | 1973 |
| John Pollock Designs for Disabled Limited | Professional & scientific | 1999 |
| Johnie's Kitchen Ltd | Hospitality | 2024 |
| Johnsonwest Co LLP | | 2021 |
| Jollytots NI Ltd | Health & social care | 2003 |
| Jonny's Life Skills Limited | Education | 2023 |
| Jordanstown Autos Ltd | Wholesale & retail | 2009 |