| Lurgan Properties Limited | Real estate | 1965 |
| Lurgan Town Arena | Arts & recreation | 2004 |
| Lurgan Young Men's Christian Association | Education | 2007 |
| Lurganville & District Community Association | Other services | 2015 |
| Lurgill Property Services Ltd | Households | 2015 |
| Luxe Beauty Hub Ltd | Wholesale & retail | 2026 |
| Luxio International Limited | Wholesale & retail | 2025 |
| Luzzu Media Limited | Information & communication | 2017 |
| Lwni Ltd | Real estate | 2025 |
| Lylo Schoolhouse | Health & social care | 2011 |
| Lynch Lodgings Ltd | Real estate | 2025 |
| Lynden Aesthetics Limited | Other services | 2021 |
| Lyte Records Ltd | Other services | 2011 |
| Lyvel Holdings Ltd. | Information & communication | 2023 |
| M & M Distribution Limited | Wholesale & retail | 2018 |
| M & M Mechanical Ltd | Construction | 2020 |
| M & W Farm Meats Ltd | Wholesale & retail | 2017 |
| M & W Salt Properties Ltd | Real estate | 2006 |
| M B Roofing Services Ltd | Construction | 2019 |
| M Carr Contracts Ltd | Construction | 2019 |
| M Cubed Bonded Limited | Transport & logistics | 2025 |
| M Donaghy Ltd | Financial services | 2021 |
| M Electrical Contracts Ltd | Construction | 2025 |
| M GAS (N.I.) Limited | Construction | 2019 |
| M Kerr Contracts Ltd | Construction | 2010 |
| M Watson Property Investments Ltd | Real estate | 2025 |
| M&J NI Property Holdings Limited | Real estate | 2026 |
| M&R Mining Limited | Mining & quarrying | 2019 |
| M.B. Freight Forwarding Limited | Transport & logistics | 1993 |
| M.Oneill Properties Ltd | Real estate | 2026 |
| M.Patterson Transport Ltd | Transport & logistics | 2025 |
| Maarawi Food Limited | Wholesale & retail | 2025 |
| Mabel 2024 Limited | Hospitality | 2024 |
| MAC Commerce Ltd | Wholesale & retail | 2024 |
| MAC Ivors Cider Co. Limited | Manufacturing | 2013 |
| MAC Machinery Sales N.I Ltd | Wholesale & retail | 2018 |
| Mac.Recovery N.I Ltd | Transport & logistics | 2021 |
| Mach Technologies Ltd | Wholesale & retail | 2018 |
| Mackle Engineering Services Ltd | Construction | 2018 |
| Mackle Ltd | Professional & scientific | 2026 |
| Mackleton Ltd | Wholesale & retail | 2020 |
| Macklin Fuelling Solutions Ltd | Manufacturing | 2026 |
| Macneice Fruit Limited | Manufacturing | 2006 |
| Madden Heights Management Company Limited | Real estate | 2008 |
| Madden Interiors Ltd | Wholesale & retail | 2015 |
| Made and Measured Ltd | Other services | 2018 |
| Madu Holdings Ltd | Real estate | 2026 |
| Maggie MC Creations Ltd | Manufacturing | 2025 |
| Magheralin Hall Co Ltd | Other services | 2015 |
| Magheralin Parish Caring Association | Other services | 2011 |
| Magpie Boutique Ltd | Wholesale & retail | 2026 |
| Maguire Quality Hams Ltd | Manufacturing | 2010 |
| Maguire Security Systems Ltd | Administrative & support | 2020 |
| Mahon Court Management Limited | Households | 2005 |
| Mahon Foods Limited | Manufacturing | 2026 |
| Mahon Road Garage Ltd | Wholesale & retail | 2015 |
| Main MEN Limited | Administrative & support | 2019 |
| Main Street House Limited | Hospitality | 2021 |
| Make IT Happen Engineering Ltd | Professional & scientific | 2025 |
| Makens Construction Ltd | Construction | 2026 |
| Makens Foods Limited | Wholesale & retail | 2026 |
| Makes & Deliver Limited | Construction | 2025 |
| Malcomsons Funeral Service Ltd | Other services | 1991 |
| Mallon Property Ltd | Real estate | 2024 |
| Mallon Scaffolding Ltd | Construction | 2007 |
| Mallon Transport Services Limited | Professional & scientific | 2016 |
| Mamma D Ltd | Wholesale & retail | 2019 |
| Management Solutions (N.I.) Ltd | Professional & scientific | 2016 |
| Manfreight International Limited | Transport & logistics | 2017 |
| Manfreight Limited | Transport & logistics | 2005 |
| Manor Financial Ltd | Administrative & support | 2020 |
| Manse View Management Company Limited | Households | 2017 |
| Manufacturing and Business Solutions Ltd | Professional & scientific | 2018 |
| Manus Holdings Ltd | Real estate | 2010 |
| Maralin Safety Systems Ltd | Manufacturing | 2011 |
| Marble Hill Retail Limited | Wholesale & retail | 2011 |
| Marie Minks Ltd | Wholesale & retail | 2022 |
| Mark White Plumbing & Heating Ltd | Construction | 2023 |
| Markethill Livestock & Farm Sales Ltd | Wholesale & retail | 2001 |
| Markethill Meat Ltd | Wholesale & retail | 2024 |
| Marlin Agency Limited - the | Health & social care | 1968 |
| Marlin Services (N.I.) Ltd | Manufacturing | 2022 |
| Marron Heating Ltd | Construction | 2023 |
| Marsden Property Services Ltd | Professional & scientific | 2016 |
| Marys Moira Limited | Hospitality | 2025 |
| Mashalcomm Ltd | Wholesale & retail | 2024 |
| Mask Packaging Limited | Administrative & support | 2025 |
| Mason Formwork Ltd | Construction | 2011 |
| Massey Catering Equipment Limited | Wholesale & retail | 2012 |
| Matrex Mats & Matting Limited | Manufacturing | 2001 |
| Matrix Competitions Ltd | Wholesale & retail | 2026 |
| Matthews Orthopaedics Ltd | Health & social care | 2025 |
| Maurice Cushnie Architects Limited | Professional & scientific | 2006 |
| Mawhillen Steel Works Ltd | Manufacturing | 2021 |
| Maxwell Hygiene Ltd | Administrative & support | 2013 |
| May/Day Events Ltd | Administrative & support | 2019 |
| Maya Labs Ltd | Other services | 2026 |
| Mayfair Associated Investments (UK) Limited | Financial services | 2012 |
| Maynooth Manor Property Management Ltd | Households | 2016 |
| Mayola Construction Ltd | Construction | 2005 |