| Gribben Brickwork Limited | Construction | 2025 |
| GRM Autos Ltd | Wholesale & retail | 2018 |
| Gronan Wind Farm Limited | Energy | 2007 |
| Grow Trend Ltd | Wholesale & retail | 2025 |
| Growing Beyond Limited | Professional & scientific | 2012 |
| Growth Marketing (N.I.) Ltd | Professional & scientific | 2019 |
| GRZ Properties Limited | Real estate | 2023 |
| GTG Biogas (Ballymoyle) Limited | Energy | 2011 |
| H&F E-Commerce Ltd | Wholesale & retail | 2024 |
| Hagan Builders Ltd | Construction | 2011 |
| Hagan Contracts Ltd | Construction | 2018 |
| Hamills Lane Properties Ltd | Administrative & support | 2012 |
| Hamilton Metal Forming Ltd | Manufacturing | 2021 |
| Hamilton Pelleting Solutions Ltd | Manufacturing | 2024 |
| Handicraftsmen Ltd | Wholesale & retail | 2025 |
| Hardiz Construction Ltd | Construction | 2023 |
| Harkness Plant Hire Ltd | Construction | 2006 |
| Health and Safety Services (NI) Limited | Professional & scientific | 2012 |
| Heart Flag of Lithuania CIC | Education | 2025 |
| Heron Financial and Management Consulting Ltd | Professional & scientific | 2021 |
| Heron Fitout Limited | Real estate | 2014 |
| Heron Freight Services Limited | Transport & logistics | 2026 |
| Heron Group Properties Ltd | Real estate | 2020 |
| High Road Services Ltd | Extraterritorial | 2004 |
| Highcross Enterprises Ltd | Real estate | 2017 |
| Hillcrest Wholesale Ltd | Wholesale & retail | 2015 |
| Hillview Property Solutions Ltd | Real estate | 2026 |
| Hinge Holdings Ltd | Energy | 2024 |
| Hiskey Limited | Professional & scientific | 2010 |
| Holly Heights Company Limited | Extraterritorial | 2020 |
| Home Floorz Ltd | Construction | 2016 |
| Home Home: Furniture and Furnishings Ltd | Wholesale & retail | 2022 |
| Hoop Construction Limited | Construction | 2018 |
| Hooper Technologies Limited | Manufacturing | 2019 |
| Hoover Investments Limited | Construction | 2013 |
| Hughes Facilities Management (N.I.) Ltd | Construction | 2018 |
| Hughes Facilities Management Claims Ltd | Information & communication | 2025 |
| Hughes Glazing Ltd | Manufacturing | 2012 |
| Hurdal Limited | Arts & recreation | 2015 |
| Hutchinson Trading Ltd | Real estate | 2025 |
| Hydro DRY Ltd | Construction | 2022 |
| IAN Stores Limited | Wholesale & retail | 2025 |
| IDR Holdings Ltd | Real estate | 2016 |
| Igmss Inc Limited | Manufacturing | 2026 |
| IJ Couriers Ltd | Transport & logistics | 2020 |
| IL Contracts Limited | Construction | 2026 |
| Indigo Energy Systems Ltd | Manufacturing | 2023 |
| Inflatable World Cookstown Ltd | Arts & recreation | 2025 |
| Inniovate Ltd | Financial services | 2022 |
| Innoled Limited | Wholesale & retail | 2018 |
| Innova Consultants Ltd | Professional & scientific | 2025 |
| Inspired Media Ltd | Information & communication | 2025 |
| Interwind Ltd | Construction | 2010 |
| Invennity Ltd | Financial services | 2022 |
| ITS Cheaper UP North.Com Limited | Wholesale & retail | 2011 |
| IVY & Co Hospitality Ltd | Hospitality | 2025 |
| J & K Contracts Limited | Construction | 2014 |
| J & M Developers Ltd | Construction | 2015 |
| J B Auto Sales NI Ltd | Wholesale & retail | 2017 |
| J Hutton Butchers Ltd | Wholesale & retail | 2015 |
| J M Paving Solutions Ltd | Construction | 2015 |
| J. Dornan Wholesale Limited | Wholesale & retail | 2002 |
| J. Lennon & Co. Limited | Wholesale & retail | 2000 |
| J.P. Nugent Ltd | Construction | 2017 |
| Jadi Limited | Energy | 2017 |
| Jarlath Martin Groundworks Limited | Construction | 2019 |
| JB Retail N.I. Ltd | Wholesale & retail | 2025 |
| JC Plastering Contractors Ltd | Construction | 2019 |
| JCA Ninety Seven Limited | Health & social care | 2021 |
| Jcmc Property Ltd | Real estate | 2026 |
| JCR Granite Ltd | Wholesale & retail | 2018 |
| JD Catering Supplies Limited | Manufacturing | 2014 |
| JD Excavations Tyrone Limited | Construction | 2009 |
| JD Reilly Transport Ltd | Transport & logistics | 2024 |
| JDC Building Works Ltd | Construction | 2018 |
| JDQ 2 Limited | Extraterritorial | 2012 |
| Jenny Wren Services Limited | Hospitality | 2025 |
| JF Contracts (N.I.) Ltd | Construction | 2017 |
| JFB Logistics Ltd | Transport & logistics | 2017 |
| JIG SAW Farm Community Interest Company | Agriculture & fishing | 2020 |
| JJ Loughran Holdings Ltd | Financial services | 2013 |
| JJ Loughran Ltd | Manufacturing | 2013 |
| Jjcc Holdings Ltd | Financial services | 2021 |
| Jjdh Ltd | Hospitality | 2020 |
| Jjpo Limited | Financial services | 2018 |
| JKC Spraying Services Ltd | Manufacturing | 2025 |
| JMB Coaches 2 Ltd. | Transport & logistics | 2010 |
| Joanne Mcquillan Contracting Ltd | Construction | 2019 |
| Joes Cookstown Taxi Company Limited | Transport & logistics | 2025 |
| John Lynn Holdings Ltd | Financial services | 2024 |
| John Lynn Plumbing & Heating Ltd | Construction | 2014 |
| Joma Trading Ltd | Wholesale & retail | 2011 |
| Jordan Precision Engineering Ltd | Manufacturing | 2025 |
| Joseph Hardy Tractors Ltd | Manufacturing | 2012 |
| Josso Properties Limited | Real estate | 2020 |
| Josso Treasury Limited | Professional & scientific | 2020 |
| JP Lagan Ltd | Construction | 2021 |
| JR & S Ltd | Construction | 2024 |
| K Holdings (NI) Ltd | Administrative & support | 2012 |
| K-Tec Automation Ltd | Information & communication | 2007 |