| H2 Pedagogy Ltd | Education | 2023 |
| Hampton Lawn Care Ltd | Administrative & support | 2013 |
| Hanna Burns Ltd | Professional & scientific | 2025 |
| Hawthorn Hideaways Ltd | Hospitality | 2024 |
| Healthy Little Lifter (2020) Ltd | Other services | 2020 |
| Healthy Little Lifter Ltd | Other services | 2018 |
| Herron Contractors Ltd | Construction | 2010 |
| Hibiscus Commercial Limited | Construction | 2018 |
| Hidavid Limited | Information & communication | 2006 |
| High Tech Surveying Ltd | Professional & scientific | 2020 |
| Hill Fitness Ltd | Wholesale & retail | 2020 |
| Hillsborough Taxis Ltd | Transport & logistics | 2025 |
| Hillside Dairy Farms Limited | Agriculture & fishing | 2012 |
| Hilltown Hides | Extraterritorial | 1989 |
| Hinch Developments Ltd | Construction | 2015 |
| Holly Rose Homes Ltd | Real estate | 2024 |
| Homegrown (N.I) Limited | Wholesale & retail | 2016 |
| Homeworks Build Ltd | Construction | 2020 |
| Hot Yoga Cookstown Ltd | Other services | 2024 |
| HR Developments Ltd | Construction | 2025 |
| Hubark Properties Limited | Real estate | 1980 |
| I B Networks Trust | Information & communication | 2009 |
| IAN Lougher Ltd | Arts & recreation | 2010 |
| Ianmart Healthcare Ltd | Extraterritorial | 2022 |
| Ianmart Limited | Health & social care | 2013 |
| Idat Marine Ltd | Manufacturing | 2023 |
| IE Associates Ltd | Information & communication | 2017 |
| IK Aggregates Ltd | Transport & logistics | 2016 |
| Imagine Composites Ltd | Professional & scientific | 2011 |
| Inspired by Flowers Ltd | Wholesale & retail | 2022 |
| Ipeh Limited | Energy | 2011 |
| Island Dairies (N.I) Ltd | Manufacturing | 2020 |
| Island Dairies Farm Limited | Agriculture & fishing | 2021 |
| Islandderry Trout Fishery Limited | Agriculture & fishing | 2024 |
| Iveagh Residential Management Limited | Households | 2025 |
| J & P Pubs (N.I.) Ltd | Hospitality | 2018 |
| J H Cooling Solutions Ltd | Energy | 2026 |
| JD Espresso Repair Ltd | Wholesale & retail | 2026 |
| Jean Marie Arsene Delbart Ltd | Extraterritorial | 2024 |
| Jesters Daycare Ltd | Health & social care | 2022 |
| JFM Joinery Ltd | Construction | 2023 |
| JJP Haulage Limited | Transport & logistics | 2012 |
| JMK Property Developments Limited | Professional & scientific | 2023 |
| Jmkm Investments Ltd | Financial services | 2026 |
| JNJ Homes Limited | Construction | 2006 |
| John Bamber & Company Limited | Financial services | 2011 |
| John Chambers Agricultural Services Ltd | Agriculture & fishing | 2011 |
| John Mcdowell Civil Engineering Limited | Construction | 1997 |
| John Watson SMS Limited | Construction | 2012 |
| Johnston Shields CQS Limited | Professional & scientific | 2024 |
| Jonah James Ltd | Administrative & support | 2023 |
| Jones Garden Care Ltd | Administrative & support | 2024 |
| Joseph Murray Limited | Professional & scientific | 2013 |
| Journey Free Limited | Arts & recreation | 2014 |
| Juco Associates Ltd | Professional & scientific | 2018 |
| Juco Innovation Advisory Ltd | Professional & scientific | 2026 |
| Juco Ventures Ltd | Financial services | 2026 |
| Juno Composites Ltd | Professional & scientific | 2011 |
| Just Like Mama’S Ltd | Hospitality | 2025 |
| JWR Design Ltd | Professional & scientific | 2019 |
| K P Decor Ltd | Construction | 2016 |
| K-Quip Ltd | Manufacturing | 2021 |
| K-Quip UK Sales Ltd | Wholesale & retail | 2023 |
| KB Electrical Ireland Ltd | Construction | 2024 |
| Kelly Houses Limited | Financial services | 2014 |
| Kenorth Limited | Real estate | 2021 |
| Kflows Ltd | Information & communication | 2026 |
| Kildrum Kennels Ltd | Agriculture & fishing | 2020 |
| Killysorrell Properties Ltd | Real estate | 2010 |
| Kinallen Mews Management Company Limited | Households | 2020 |
| Kirk Security Solutions Ltd | Administrative & support | 2024 |
| KPM Recruiting NI Ltd | Administrative & support | 2023 |
| Krazi Baker Ltd. | Hospitality | 2014 |
| L. Riddle Haulage Limited | Transport & logistics | 2018 |
| Lagan Bann Joinery & Construction Ltd | Construction | 2024 |
| Lagan Landscapes Ltd | Administrative & support | 2023 |
| Lagan Valley Hemp Ltd | Other services | 2022 |
| Lakemount Free Range Eggs Ltd | Agriculture & fishing | 2023 |
| Lanpro Investments Ltd | Real estate | 2013 |
| Laurelhill Ltd | Real estate | 2025 |
| Laurelmount Meadows Ltd | Households | 2022 |
| Leadwise Contracts Limited | Construction | 2004 |
| Lexify Ltd | Professional & scientific | 2024 |
| Life Financial Protection Solutions Ltd | Financial services | 2021 |
| Lisnasure Home Deliveries Limited | Wholesale & retail | 2019 |
| Lockhart Software Limited | Information & communication | 2022 |
| Loughshore Lodges Ltd | Hospitality | 2025 |
| Loughview Holdings Ltd | Construction | 2018 |
| Loved INK Tattoo & Piercing Academy Ltd | Education | 2024 |
| Lyttle Transport Limited | Transport & logistics | 2023 |
| M a Quail Limited | Wholesale & retail | 2002 |
| M O'Neill Contracts Ltd | Construction | 2026 |
| M T Plant and Equipment Ltd | Wholesale & retail | 2024 |
| M Travers Autos Ltd | Wholesale & retail | 2016 |
| Magysfarm Ltd | Arts & recreation | 2023 |
| Mairi Kennedy Therapy Ltd | Health & social care | 2020 |
| Marshall and Lyle Ltd | Hospitality | 2023 |
| Martin Cromwell Car Sales Limited | Wholesale & retail | 2014 |
| Massford Construction Ltd | Construction | 2016 |
| Maypole Farm Limited | Agriculture & fishing | 2010 |