| JAY V P Ltd | Financial services | 2022 |
| Jbjjpf Limited | Professional & scientific | 2019 |
| Jbms Limited | Administrative & support | 2002 |
| JC Engineering and Fabrication Ltd | Professional & scientific | 2020 |
| Jdmr Limited | Professional & scientific | 2011 |
| Jeff Blair Construction Ltd | Construction | 2016 |
| JH Harshaw Limited | Construction | 2021 |
| JHT (Carrowdore) Limited | Real estate | 2019 |
| JHT (Library Services) Limited | Real estate | 2004 |
| JHT (Lisburn) Limited | Extraterritorial | 2004 |
| JHT Clare Limited | Real estate | 2005 |
| JHT Global Point Limited | Construction | 2022 |
| JHT Hotels Limited | Hospitality | 2017 |
| JHT Property Development Limited | Real estate | 2009 |
| JHT Upperlands Limited | Construction | 2007 |
| JHT UUJ Ltd | Real estate | 2006 |
| Jmcp Solutions Ltd | Administrative & support | 2025 |
| John Gallagher Builders Ltd | Construction | 2022 |
| John Mcatamney Ltd | Professional & scientific | 2016 |
| Just ADD Lemonade Ltd | Professional & scientific | 2022 |
| Just Desserts & Pastries Ltd | Manufacturing | 2020 |
| Kast Enterprises Ltd | Hospitality | 2011 |
| KBC Coach Company Ltd | Transport & logistics | 2024 |
| Kencro Developments Limited | | 1988 |
| Kensington Mews LMC Limited | Administrative & support | 2015 |
| Kestrel Foods Limited | Manufacturing | 1996 |
| KI & BI Ltd | Transport & logistics | 2021 |
| Kids United Playgroup Portadown Ltd | Health & social care | 2020 |
| Killahoey Limited | Real estate | 2022 |
| Killderg Limited | Hospitality | 2013 |
| Kitchen Bakes Limited | Manufacturing | 2003 |
| Kmwb Group Ltd | Information & communication | 2025 |
| Kool Kutz Ltd | Other services | 2024 |
| KP Consulting Engineers Ltd | Professional & scientific | 2024 |
| L & B Fabrication N.I Limited | Professional & scientific | 2021 |
| L&S Properties (N.I.) Limited | Real estate | 2020 |
| Lakeside Family Trust | Health & social care | 2022 |
| Landscape Design & Planning Ltd | Administrative & support | 2018 |
| Lavery Plant Hire Ltd | Transport & logistics | 2022 |
| Lavery Transport Limited | Transport & logistics | 1999 |
| LEE Lovett Ltd | Information & communication | 2016 |
| Lenos Homes Ltd | Construction | 2019 |
| Linenmill Ltd | Wholesale & retail | 2013 |
| Lisburn Astral Limited | Construction | 2001 |
| Little Larks Childcare Ltd | Health & social care | 2025 |
| Little Penguin Limited | Wholesale & retail | 2026 |
| LMC Medical Services Ltd | Health & social care | 2024 |
| LMG Developments Limited | Construction | 2013 |
| LMK International Transport Limited | Transport & logistics | 2010 |
| Logic IT Solutions Limited | Information & communication | 2003 |
| Longridge Developments Limited | Construction | 2018 |
| Loughdaw Properties Limited | Professional & scientific | 2006 |
| LRC Powder Coating & Fabrication Ltd | Manufacturing | 2023 |
| Lucky Streak Competitions Ltd | Arts & recreation | 2021 |
| Lynas Consulting Ltd | Professional & scientific | 2012 |
| Lynhill Properties Limited | Construction | 2007 |
| Magma Stream Design Ltd | Manufacturing | 2011 |
| Mailey Consultancy Services Limited | Professional & scientific | 2006 |
| Manderley Mews Management Company Limited | Households | 2003 |
| Mangovale Ltd | Financial services | 2024 |
| Manufacturing Northern Ireland | Other services | 2009 |
| Marfagh Ltd | Real estate | 2025 |
| Mark Willis Ltd | Information & communication | 2021 |
| Martello (Holywood) Limited | Construction | 2025 |
| Mary Mackle & Co. Ltd | Professional & scientific | 2005 |
| Matchless Machining Limited | Manufacturing | 2006 |
| Mbcw Properties Ltd | Real estate | 2014 |
| MCB Concrete Services Ltd | Construction | 2015 |
| Mccann Apples Limited | Manufacturing | 2020 |
| Mccann Orchards Limited | Manufacturing | 2026 |
| Mccourt Holdco Ltd | Professional & scientific | 2016 |
| Mcgarry & Co Chartered Accountants Ltd | Professional & scientific | 2024 |
| MCI Fabrications Ltd | Manufacturing | 2023 |
| Mckeever Sports Ltd | Extraterritorial | 2019 |
| Mckvr Group Ltd | Wholesale & retail | 2004 |
| Mcmurdie Electrics Limited | Construction | 2023 |
| MCR Watercoolers Limited | Administrative & support | 2018 |
| Mcwilliam IFS Ltd | Financial services | 2019 |
| Mearne Construction Ltd | Construction | 2010 |
| Mercerpme Ltd | Professional & scientific | 2020 |
| Meriton Capital Holdings Ltd | Wholesale & retail | 2025 |
| Mervyn Clayton Developments Limited | Construction | 2002 |
| MF Contracts Ltd | Construction | 2013 |
| Mftt Ltd | Administrative & support | 2023 |
| Milligan Farms | Agriculture & fishing | 2024 |
| Milne Funeral Services Ltd | Other services | 2011 |
| Minde's Transport Ltd | Transport & logistics | 2017 |
| Mmrl Limited | Real estate | 2014 |
| Mollmac Ltd | Construction | 2012 |
| Monclone Farm Ltd | Agriculture & fishing | 2025 |
| Mountnorris Developments LLP | | 2023 |
| MSC (Erneside) Ltd | Real estate | 2025 |
| MTM Lubricants Ltd | Wholesale & retail | 2009 |
| Murray Tyres (Holdings) Limited | Other services | 2016 |
| Murray Tyres Wholesale Ltd | Wholesale & retail | 2022 |
| N.I Broadcast Ltd | Manufacturing | 2011 |
| New Charlestown Retail Limited | Extraterritorial | 2013 |
| New Ground Ireland Limited | Other services | 2017 |
| New Leaf Tree Services Ltd | Administrative & support | 2026 |
| Nf&July Ltd | Transport & logistics | 2022 |