| Houston Solutions Ltd | Professional & scientific | 2010 |
| HR Inventory Services Limited | Administrative & support | 2017 |
| HTI Orthopaedics Ltd | Health & social care | 2013 |
| Hubzy Ltd. | Information & communication | 2019 |
| Hunt Solicitors Limited | Professional & scientific | 2012 |
| Hutchinson Homes Limited | Health & social care | 2005 |
| HWD Developments Limited | Real estate | 2022 |
| HWD Group Ltd | Extraterritorial | 2016 |
| HWD Investments Limited | Real estate | 2022 |
| Hydro-Axis Solutions Ltd | Professional & scientific | 2025 |
| Hydromech NI Ltd | Construction | 2023 |
| Hypco (NI) Limited | Hospitality | 2018 |
| Hyphen (N.I.) Limited | Professional & scientific | 2018 |
| Icarus Communications Ltd | Professional & scientific | 2015 |
| Ilsi Ltd | Manufacturing | 2019 |
| Impact Housing Limited | Real estate | 2025 |
| Impact PR & Communications Ltd | Professional & scientific | 2019 |
| Indie Film Project Limited | Information & communication | 2016 |
| Informed Property Management Ltd | Real estate | 2020 |
| Initial Publishing Limited | Extraterritorial | 2003 |
| Inkintelligent Limited | Manufacturing | 2018 |
| Inpolicy Insights Limited | Financial services | 2015 |
| International Luxury Media Ltd | Information & communication | 2019 |
| Inverpath Limited | Health & social care | 2022 |
| Invictus 50 Ltd | Professional & scientific | 2022 |
| IQ Financial LLP | | 2008 |
| Iq&Co Limited | Professional & scientific | 2017 |
| Irish Naturalists' Journal Limited -the | Information & communication | 1992 |
| Irish Paediatric Neurology Limited | Health & social care | 2019 |
| Isdm Holdings Ltd | Information & communication | 2024 |
| Italic PUG Limited | Information & communication | 2017 |
| J and N Foods Limited | Hospitality | 2024 |
| J Cupitt Sports Academy Limited | Education | 2019 |
| J D Browne Consulting Limited | Professional & scientific | 2024 |
| J&C Property Holdings (NI) Limited | Construction | 2015 |
| J&L (NI) Limited | Wholesale & retail | 2009 |
| J.Dean Limited | Real estate | 1973 |
| J.I.F.E. Developments Limited | Real estate | 1987 |
| Jamie Hegarty Ltd | Information & communication | 2024 |
| Jamison Accounting Limited | Professional & scientific | 2018 |
| Jcom Network Solutions Ltd | Information & communication | 2009 |
| JEM Housing Ltd | Real estate | 2017 |
| Jeragh Property Limited | Real estate | 2023 |
| Jesselle Fabrics Ltd | Wholesale & retail | 2017 |
| Jeta Media & Events Ltd | Arts & recreation | 2021 |
| Jettora Limited | Professional & scientific | 2013 |
| JHA15 Property Limited | Real estate | 2015 |
| JIT Education Limited | Education | 2018 |
| Jjni Property Limited | Other services | 2023 |
| JK Consulting Associates Ltd | Professional & scientific | 2021 |
| Jlsc Limited | Wholesale & retail | 2023 |
| JM Connected Ltd | Information & communication | 2023 |
| JM Music Development Ltd | Other services | 2024 |
| JN Holdings (N.I.) Limited | Administrative & support | 2025 |
| Jnsayer Limited | Health & social care | 2025 |
| John Carroll Antiques Limited | Wholesale & retail | 2021 |
| John Morrison Hairdressing Ltd | Other services | 2024 |
| John Rath Limited | Administrative & support | 1962 |
| Jonsson Consultancy LLP | | 2022 |
| Jordan Consulting (N.I.) Limited | Professional & scientific | 2019 |
| Joule Assets UK Ltd | Professional & scientific | 2020 |
| Joxer Harrison Ltd | Hospitality | 2020 |
| Joxer Hillsborough Limited | Hospitality | 2023 |
| Joya Wellness Limited | Hospitality | 2024 |
| JR Marbel Limited | Hospitality | 2018 |
| JRX Limited | Information & communication | 2021 |
| JS Reynolds Ltd | Professional & scientific | 2016 |
| JSG Davidson Ltd | Administrative & support | 2021 |
| Jsjb Investments Limited | Financial services | 2025 |
| JT Developments (N.I.) Ltd | Construction | 2021 |
| JT Imaging Ltd | Health & social care | 2015 |
| JTA Geological Services Limited | Professional & scientific | 2014 |
| JTJ (Omagh Central) LLP | | 2017 |
| JTJ Strabane Limited | Construction | 2015 |
| Jura Limited | Real estate | 1988 |
| JY Real Estate Limited | Real estate | 2023 |
| K & L Medical Limited | Health & social care | 2011 |
| Kalzak Limited | Health & social care | 2024 |
| Kanwei Ltd | Other services | 2022 |
| Kater Agencies Limited | Households | 1988 |
| Kccl Ltd | Professional & scientific | 2020 |
| Kearney Investments Limited | Real estate | 1997 |
| Keasim Belfast Limited | Real estate | 2025 |
| Keeperlit Ltd | Construction | 2021 |
| Kelynn Ltd | Hospitality | 2021 |
| Keywest Trading Limited | Wholesale & retail | 2018 |
| Kiddieland Limited | Arts & recreation | 1984 |
| KIN & Kind Ltd | Manufacturing | 2018 |
| Kirker Watch Company Ltd | Wholesale & retail | 2020 |
| KLR Trading Ltd | Transport & logistics | 2015 |
| KMJ Locum Limited | Health & social care | 2016 |
| Knockbracken Investment Company Limited | Real estate | 1959 |
| L1 Property Solutions Ltd | Real estate | 2011 |
| LA Devlin Immunology Consulting Ltd | Professional & scientific | 2017 |
| Lacefield Management Company Limited | Real estate | 2012 |
| Lacuna Developments LLP | | 2021 |
| Lacuna Holdings Limited | Construction | 2016 |
| Lacuna Property Limited | Construction | 2002 |
| Lady Financial Adviser Limited | Professional & scientific | 2025 |
| Lady Financial Advisor Limited | Professional & scientific | 2025 |