| Mullan Landscapes Ltd | Construction | 2018 |
| Mullen Auto Sales Ltd | Wholesale & retail | 2019 |
| Mullen Autos Ltd | Wholesale & retail | 2025 |
| Mullen Developments Ltd | Construction | 2023 |
| Multi-Crete N.I. Limited | Manufacturing | 2024 |
| Mulvin Valley Dairy Ltd | Real estate | 2024 |
| Murphys on the Green Ltd | Hospitality | 2011 |
| Music Loopy Ltd | Information & communication | 2023 |
| My Builders Merchant Ltd | Wholesale & retail | 2019 |
| My Local NI Ltd | Professional & scientific | 2019 |
| My POD My Space (N.I.) Ltd | Construction | 2020 |
| MZ Event Flowers Limited | Wholesale & retail | 2021 |
| N & R Devine Ltd | Real estate | 1999 |
| N&P Construction Limited | Construction | 2025 |
| N&R Rentals Ltd | Construction | 2016 |
| Nails Lounge & Spa Ltd | Other services | 2025 |
| Needfreight Ltd. | Transport & logistics | 2015 |
| Neemac Plant Services Ltd. | Administrative & support | 2010 |
| Neeson Resourcing Ltd | Wholesale & retail | 2023 |
| Neil O Donnell Ltd. | Transport & logistics | 2015 |
| Neulor Ltd | Construction | 2016 |
| Nevuary Limited | Wholesale & retail | 2021 |
| New Beginnings Scan Ltd | Health & social care | 2024 |
| New Ross Limited | Construction | 2016 |
| Newbic Consultancy Limited | Information & communication | 2019 |
| Nexgen Peptides Ltd | Wholesale & retail | 2025 |
| NI Cosy Room Ltd | Construction | 2022 |
| NI Discount Fuels Limited | Extraterritorial | 2015 |
| NI Housing Associates Ltd | Hospitality | 2026 |
| NI Trade Cars Ltd | Wholesale & retail | 2026 |
| NI620786 Limited | Construction | 2013 |
| Nico's Turkish Barber Shop Ltd | Other services | 2022 |
| Nicu and YOU CIC | Other services | 2025 |
| Nirysha Investments Ltd | Real estate | 2026 |
| Nirysha Properties Ltd | Construction | 2015 |
| NJL Precision Engineering Ltd | Manufacturing | 2014 |
| NMG Tints Ltd | Wholesale & retail | 2025 |
| Nolijwork Ltd | Information & communication | 2018 |
| Nonzerosum Ltd | Information & communication | 2022 |
| North West Décor Ltd | Construction | 2025 |
| North West Tiles Bathrooms & Flooring Limited | Manufacturing | 2024 |
| Northern Contract Crushing Ltd | Mining & quarrying | 2022 |
| Northern Quarries (Mountfield) Ltd | Mining & quarrying | 2021 |
| Northface Access Scaffolding Ltd | Construction | 2014 |
| Northface Access Services (NI) Limited | Construction | 2007 |
| Northlink Fleet Sales Ltd | Wholesale & retail | 2026 |
| Northwest Adhd Assessment Centre Ltd | Health & social care | 2021 |
| Northwest New Build Ltd | Construction | 2026 |
| Northwest Quality Motors Ltd | Wholesale & retail | 2021 |
| Notlen Group Ltd | Professional & scientific | 2021 |
| O'Neill Fencing Limited | Construction | 2011 |
| O'Neill Properties Limited | Real estate | 2006 |
| Oakpark Enterprises Ltd | Professional & scientific | 2023 |
| Oaks Fishing Ltd | Agriculture & fishing | 2021 |
| Ocean Property Hold Limited | Real estate | 2013 |
| ODB Engineering Ltd | Public administration | 2024 |
| Oliver Roche LLP | | 2017 |
| OM Trading Limited | Wholesale & retail | 2011 |
| Omagh Pest Control Ltd | Administrative & support | 2025 |
| One Blank Wall Ltd | Manufacturing | 2015 |
| ONL Holdings Limited | Financial services | 2025 |
| Outer Space Pods Ltd | Construction | 2018 |
| Oysters Restaurant & Winebar Ltd | Hospitality | 2013 |
| P Greer Engineering Ltd | Construction | 2015 |
| P K Wholesalers Limited | Wholesale & retail | 2009 |
| P Kelly Ltd | Construction | 2013 |
| P Mccrossan & SON Contracts Ltd | Construction | 2021 |
| P Mulrine and Sons Sales (U.K.) Limited | Manufacturing | 2016 |
| P Woods & SON Ltd | Construction | 2015 |
| P&C Aerials Ltd | Manufacturing | 2018 |
| P&C Mcgettigan Limited | Construction | 2004 |
| P.G. Mcgillion (Motors) Limited | Wholesale & retail | 1976 |
| P.J. Gillespie Plant Sales Limited | Wholesale & retail | 1999 |
| P.O'Neill (Building Services) Ltd | Construction | 1995 |
| PAC Ltd | Real estate | 2024 |
| Park House Red Properties Limited | Real estate | 2019 |
| Parker Psychology Northwest Limited | Health & social care | 2025 |
| Parker Safety Training Services Ltd | Education | 2022 |
| Parkhill Transport NI Ltd | Transport & logistics | 2023 |
| Parkland 33 Ltd | Hospitality | 2024 |
| Parkview Veterinary Clinic Limited | Professional & scientific | 2003 |
| PAT Kirk Limited | Wholesale & retail | 1977 |
| Patterson Caravans Limited | Wholesale & retail | 1986 |
| Paul Tully Tyres (NI) Ltd | Wholesale & retail | 2014 |
| PC Plumbing Heating & Sons Ltd | Construction | 2013 |
| PCM Autosales Ltd | Wholesale & retail | 2026 |
| PD Data Solutions Ltd | Information & communication | 2023 |
| PD Motors (N.I) Ltd | Wholesale & retail | 2019 |
| Peacock Farms Poultry Limited | Agriculture & fishing | 2012 |
| Peak Performance Fitness Centre (NI) Limited | Arts & recreation | 2014 |
| Pearse Road Tyre Centre (Letterkenny) Ltd | Administrative & support | 2016 |
| Peter Smyth International Sports Horses Ltd | Agriculture & fishing | 2014 |
| Petram Environmental Ltd | Professional & scientific | 2016 |
| Petroleum Forecourt Maintenance Ltd | Manufacturing | 2019 |
| Peugtekni Limited | Wholesale & retail | 2026 |
| Phoenix Fire Protection (NW) Ltd | Public administration | 2026 |
| Phoenix House HAN Ltd | Hospitality | 2024 |
| PJ Mccolgan Ltd | Financial services | 2022 |
| PKD Motors Ltd | Wholesale & retail | 2016 |
| Play Fanatics Limited - the | Other services | 2008 |