| MOY Equestrian Centre Limited | Agriculture & fishing | 2011 |
| Moylagh Health Care Consultancy Ltd | Public administration | 2025 |
| MPG Castlegore Ltd | Energy | 2024 |
| MPG Omnipower Ltd | Energy | 2024 |
| MPG Shinny RD Ltd | Energy | 2011 |
| MPG Wind Ltd | Other services | 2012 |
| MPG Wind Services Ltd | Manufacturing | 2018 |
| MSM Truck and Plant Ltd | Wholesale & retail | 2025 |
| MTA Trading Ltd | Hospitality | 2023 |
| MTO Engineering Services Ltd | Professional & scientific | 2020 |
| Mullagharn Ltd | Extraterritorial | 2017 |
| Mullaghbell Limited | Real estate | 2001 |
| Mullaghmena Maintenance Limited | Administrative & support | 2014 |
| Mullaghmore Bakery Ltd | Manufacturing | 2009 |
| Mullan Building Contracts Ltd | Construction | 2018 |
| Mullan Engineering Works Ltd | Manufacturing | 2018 |
| Mullan Family Farm Ltd | Agriculture & fishing | 2018 |
| Mullanboy Plant Hire Ltd | Administrative & support | 2019 |
| Mullaslin Limited | Real estate | 2015 |
| Mullawhinney Farm Ltd | Agriculture & fishing | 2015 |
| Mullen Investment Holdings Ltd | Real estate | 2022 |
| Mullen Motors (Omagh) Ltd | Wholesale & retail | 2016 |
| Mullin Construction Ltd | Construction | 2025 |
| Multec Limited | Manufacturing | 2017 |
| Murphyap Ltd | Construction | 2025 |
| Murrays Retail Ltd | Financial services | 2023 |
| Must Communications Ltd | Information & communication | 2024 |
| Mvwc Consulting Ltd | Water & waste | 2023 |
| N O'Connor Poultry Ltd | Agriculture & fishing | 2016 |
| N&C Commercials Ltd | Wholesale & retail | 2023 |
| Nakayama R&D Ltd | Manufacturing | 2023 |
| Nallum Ltd | Construction | 2005 |
| Narport Limited | Real estate | 2024 |
| Nate NMC Investments Ltd | Real estate | 2024 |
| Nature Trail (Omagh) Ltd. | Wholesale & retail | 2018 |
| Naturelle Consumer Products Limited | Manufacturing | 1987 |
| NC Tractor Spares Ltd | Wholesale & retail | 2022 |
| NCM Safety Systems Ltd | Construction | 2010 |
| Necq Property Limited | Real estate | 2026 |
| NED Properties Ltd | Real estate | 2024 |
| Neil Mellon Properties Limited | Real estate | 2025 |
| NEK Restaurants Ltd | Hospitality | 2004 |
| Ness Lodges Ltd | Hospitality | 2020 |
| Nethercote Bathroom & Tiles Ltd | Wholesale & retail | 2024 |
| Netzero AMS Ltd | Professional & scientific | 2022 |
| New Generation Agriculture Ltd | Wholesale & retail | 2013 |
| Newkey Enterprises Ltd | Construction | 2024 |
| Newpark Homes (N.I.) Ltd | Financial services | 2018 |
| Newquay Enterprises Ltd | Construction | 2023 |
| Newtownstewart Leisure Complex Limited | Real estate | 1999 |
| Newtownstewart Livestock Sales, Limited | Real estate | 1959 |
| Nextrak Ltd | Manufacturing | 2025 |
| Nexus Fibre Optic Ltd | Wholesale & retail | 2014 |
| NI & ROI Audit Co Ltd | Extraterritorial | 2025 |
| NI Audit Co Ltd | Extraterritorial | 2025 |
| NI Dyslexia Services Ltd | Education | 2026 |
| NI M&K Holdings Ltd | Financial services | 2020 |
| NI Will Services Ltd | Other services | 2014 |
| NI066756 Limited | Real estate | 2007 |
| NIV Limited | Wholesale & retail | 2022 |
| Nixon Joinery Contracts Ltd | Manufacturing | 2021 |
| NJB Corporate Finance Ltd | Financial services | 2020 |
| NKT Aviation Ltd | Transport & logistics | 2025 |
| NMC Flooring Ltd | Construction | 2014 |
| NMG Consultancy Services Ltd | Professional & scientific | 2022 |
| NMG Mechanical Ltd | Construction | 2018 |
| Nocht Ltd | Manufacturing | 2014 |
| Noel Bradley Ltd | Construction | 2022 |
| Nomar Ltd | Construction | 2017 |
| Nor-West Roofing Systems Ltd. | Wholesale & retail | 1990 |
| Norel Energy Services Limited | Professional & scientific | 2013 |
| North Frame Limited | Construction | 2021 |
| North South Civils Ltd | Construction | 2025 |
| North South Timber Harvesting Limited | Agriculture & fishing | 2010 |
| North West Forest Services (NI) Limited | Agriculture & fishing | 2015 |
| North West Oxygen Centre Ltd | Other services | 2021 |
| North-South Haulage Services Ltd | Transport & logistics | 2014 |
| Northwest Corridor Developments (NCD) Limited | Real estate | 2020 |
| Northwest Cranes and Access Ltd | Administrative & support | 2019 |
| Northwest Drilling Ltd | Extraterritorial | 2011 |
| Northwest Medical Limited | Manufacturing | 2020 |
| NR Jordan Ltd | Wholesale & retail | 2012 |
| NRG Accountancy Services Ltd | Professional & scientific | 2022 |
| NTG Automotive Ltd | Wholesale & retail | 2024 |
| Nuggie Ltd | Transport & logistics | 2018 |
| Nuggie's DEN Ltd | Other services | 2019 |
| O & a Consultancy Services Limited | Construction | 2013 |
| O'Brien Mechanical Limited | Construction | 2017 |
| O'Doibhilin's Ltd | Financial services | 2013 |
| O'Hagan Enterprises Ltd | Information & communication | 2019 |
| O'Kane Bros Ltd | Real estate | 2012 |
| O'Kane Family Farms Ltd | Agriculture & fishing | 2015 |
| O'Neill & Mcpolin LLP | | 2025 |
| O'Neill Concrete Flooring Ltd | Construction | 2005 |
| O'Neill Group Ltd | Financial services | 2023 |
| O'Neill Paving Ltd | Other services | 2011 |
| O'Neill Wind Energy Ltd | Energy | 2015 |
| Oakdene Renewable Energy Ltd | Energy | 2012 |
| Oakhill Property Ltd | Real estate | 2017 |
| Oakshore Investments Limited | Administrative & support | 2016 |