| Harganhg Limited | Extraterritorial | 2023 |
| Harkin Acquisition Limited | Real estate | 2023 |
| Harkin and Toth Ireland Limited | Administrative & support | 2026 |
| Harkin Management Ltd | Real estate | 2023 |
| Harkin Transport N.I. Limited | Transport & logistics | 2014 |
| Harley Funeral Services Ltd | Other services | 2019 |
| Harley WAX Ireland Limited | Wholesale & retail | 2022 |
| Harpers Quay Management Company Limited | Households | 2002 |
| Harrwood Insurance Brokers Limited | Financial services | 2014 |
| Hartlands (NI) Limited | Construction | 2013 |
| Harvest Hatch Limited | Real estate | 2017 |
| Hasson Tyres Limited | Wholesale & retail | 2012 |
| Hatmore Homes Ltd | Construction | 2023 |
| Hawei Ltd | Health & social care | 2012 |
| Hawthorn Heights Farms Ltd | Agriculture & fishing | 2015 |
| HAY Enterprises Ltd. | Water & waste | 2022 |
| Hazel Bay Company Limited | Arts & recreation | 2019 |
| HB Derry Limited | Hospitality | 2020 |
| HBG Drylining Ltd | Construction | 2017 |
| HCO Civils Limited | Construction | 2025 |
| Hcssc Properties Ltd | Real estate | 2022 |
| Heakesbury River Limited | Wholesale & retail | 2023 |
| Health for Life Supporting Community Wellbeing | Health & social care | 2001 |
| Health Tech Horizons Ltd | Professional & scientific | 2024 |
| Healthcare Solutions (Ireland) Ltd | Professional & scientific | 2024 |
| Hean Investments Ltd | Financial services | 2025 |
| Heath Hill Properties Limited | Real estate | 2015 |
| Heavron Brick Worx Limited | Construction | 2017 |
| Heiwa Satori Ltd | Real estate | 2025 |
| Helferty IT Ltd | Information & communication | 2022 |
| Helping Hand Project NI Ltd | Wholesale & retail | 2022 |
| Hempful Ltd | Manufacturing | 2016 |
| Henley Enterprises Limited | Construction | 1984 |
| Hesh Ltd | Professional & scientific | 2013 |
| Heskr Ltd | Financial services | 2026 |
| Hestia Lodgings Ltd | Real estate | 2024 |
| Hidden City Cafe Ltd | Hospitality | 2019 |
| HIE Enterprises Limited | Wholesale & retail | 2024 |
| Higher Level Cleaning Ltd | Administrative & support | 2024 |
| Hightop Hub Limited | Professional & scientific | 2025 |
| Hilclar Trading Limited | Agriculture & fishing | 2014 |
| Hill's (Derry) Limited | Financial services | 1934 |
| Hillcrest Trust (Top of the Hill) Ltd. | Health & social care | 2001 |
| Hilltown Quarry Limited | Mining & quarrying | 2022 |
| Hillview Engineering Services Limited | Professional & scientific | 2023 |
| Hip-I Limited | Administrative & support | 2003 |
| Hireflo Ltd | Administrative & support | 2026 |
| HML Group Ltd | Construction | 2018 |
| HMP Services Limited | Other services | 2021 |
| HO7NR Limited | Professional & scientific | 2014 |
| Hogan DC Ltd | Professional & scientific | 2026 |
| Hogg and Mitchells Ltd | Hospitality | 2014 |
| Hollandale Projects Limited | Construction | 2015 |
| Holly Contracts NI Ltd | Construction | 2023 |
| Holly O'Doherty Marketing Ltd | Information & communication | 2025 |
| Holly Properties Limited | Households | 2021 |
| Holm Power Ltd | Construction | 2024 |
| Holywood Road Limited | Real estate | 2013 |
| Home Solution Europe Ltd | Construction | 2025 |
| Homeward Homes Ltd | Real estate | 2025 |
| Homeward Living Limited | Health & social care | 2022 |
| Honed Flavours Ltd | Manufacturing | 2023 |
| Hope North West Temperance | Education | 2014 |
| Hope Technology Limited | Information & communication | 2023 |
| Hot Yoga Derry Ltd | Information & communication | 2025 |
| Howard Fulton Tractors Ltd | Wholesale & retail | 2002 |
| HPC Civils Ltd | Professional & scientific | 2025 |
| HPW Racing Ltd | Real estate | 2005 |
| HR Advisory NI Limited | Professional & scientific | 2023 |
| HR Team Limited | Professional & scientific | 2013 |
| HRP 53 Ltd | Transport & logistics | 2010 |
| HS Energy Limited | Energy | 2014 |
| HS Generations Ltd | Real estate | 2025 |
| HS Haulage Limited | Transport & logistics | 2018 |
| Hsls Property Ltd | Real estate | 2024 |
| HTO Developments Limited | Real estate | 2015 |
| Huallys Limited | Wholesale & retail | 2026 |
| HUB44 Ltd | Professional & scientific | 2024 |
| Huckleberry CLR Limited | Administrative & support | 2025 |
| Hunter Apparel Solutions Limited | Manufacturing | 1936 |
| Hunter Solutions Group Ltd | Manufacturing | 2008 |
| Hydro Fresh Ltd | Manufacturing | 2018 |
| Hydro Genpower Limited | Energy | 2020 |
| Hyperstride Ltd | Information & communication | 2023 |
| I Assessors Limited | Professional & scientific | 2013 |
| I'M Here Travels Ltd | Administrative & support | 2025 |
| I.F.C Groundworks Ltd | Construction | 2023 |
| I2 Total Marketing Limited | Professional & scientific | 2006 |
| IAN Parke Construction Limited | Construction | 2025 |
| Ice Cube Supplies Limited | Wholesale & retail | 2011 |
| IDC Irish Drinks Co. Ltd | Manufacturing | 2017 |
| Ideal Form Limited | Construction | 1989 |
| Idiamond Ltd. | Hospitality | 2016 |
| Ihobbs Salon and Training Academy Ltd. | Other services | 2019 |
| IHT Salon Ltd | Other services | 2025 |
| Ikigae Ltd | Financial services | 2023 |
| Imac Construction Services Limited | Construction | 2005 |
| Imac Educational Support Services Ltd | Administrative & support | 2014 |
| Imac Group Ltd | Financial services | 2015 |
| Imagene Limited | Professional & scientific | 2017 |