| Murphy Aviation Services Ltd | Manufacturing | 2026 |
| Musical Bridges CIC | Education | 2026 |
| N.K. Holdings Limited | Real estate | 1995 |
| N.K. Sporthorses Limited | Agriculture & fishing | 2023 |
| Nailedit by Lillia Ltd | Other services | 2025 |
| Narrative Films Ltd | Information & communication | 2019 |
| NC MED Ltd | Health & social care | 2025 |
| Nectar International Limited | | 2004 |
| Nedumkallel Ltd | Health & social care | 2023 |
| New Dimension 3D Ltd | Manufacturing | 2022 |
| New Dynasty Carrick Ltd | Hospitality | 2025 |
| New Ireland Trade Ltd | Wholesale & retail | 2025 |
| New Journey Group Ltd | Professional & scientific | 2017 |
| Newferry Waterski Club Ltd | Arts & recreation | 2023 |
| Newmills Hydro Systems Ltd | Manufacturing | 2024 |
| Newtownabbey Eats Limited | Hospitality | 2025 |
| Nexgen Recruitment Limited | Administrative & support | 2023 |
| NI Abbey Drains Limited | Administrative & support | 2020 |
| NI BUS Group Ltd | Transport & logistics | 2023 |
| NI Chauffeurs Ltd | Transport & logistics | 2025 |
| NI Damp Solutions Ltd | Construction | 2024 |
| NI Forklift Training Ltd | Education | 2025 |
| NI QUE Sports Ltd | Arts & recreation | 2013 |
| NI Skyline Ltd | Manufacturing | 2025 |
| Nichola Reid Limited | Other services | 2016 |
| Nisa (Northern Ireland) Limited | Extraterritorial | 2020 |
| NIX Bistro Limited | Hospitality | 2019 |
| Niya Healthcare Limited | Administrative & support | 2025 |
| Nkemunto Ltd | Health & social care | 2022 |
| NL Rigging and Lifting Ltd | Manufacturing | 2017 |
| NO GAS Caverns Ltd | Professional & scientific | 2020 |
| Noble Transport Ltd | Wholesale & retail | 2023 |
| Nomadic Watches Ltd | Wholesale & retail | 2021 |
| NORNIRON17 Ltd | Manufacturing | 2015 |
| North Court Apartments Ltd | Real estate | 2005 |
| North Shore Rentals Ltd | Real estate | 2025 |
| Northern COT Ltd | Construction | 2023 |
| Northern Passage Productions Ltd | Information & communication | 2024 |
| Northern Renewables Limited | Professional & scientific | 2004 |
| Northshore Property Limited | Real estate | 2017 |
| Novu Networks Limited | Information & communication | 2025 |
| O. Howell Property Ltd | Real estate | 2024 |
| Oak Grove Maintenance Management Limited | Households | 2003 |
| Oak Property Block Management Ltd | Households | 2019 |
| Oak Property Debt Collections (NI) Ltd | Administrative & support | 2014 |
| Oak Property Facilities Management Ltd | Households | 2019 |
| Oak Property Legal Services Ltd | Professional & scientific | 2019 |
| Oak Property Management Holding Company Ltd | Financial services | 2019 |
| Oakley Aviation Ltd | Manufacturing | 2025 |
| Oceana Mealworks Ltd | Wholesale & retail | 2025 |
| Octane London Market Limited | Financial services | 2014 |
| Officetrax UK Limited | Information & communication | 2023 |
| OJW Aviation Ltd | Construction | 2024 |
| Old Forde Estate Management Ltd | Households | 2000 |
| Old Mill Dairies Limited | Agriculture & fishing | 2024 |
| Old Mill Renewables Ltd | Energy | 2020 |
| Old Mill Saddlery Ltd | Wholesale & retail | 2014 |
| Old School Mews (Greenisland) Management Ltd | Households | 2007 |
| Old Shore Manor Management Company NO.3 Limited | Households | 2001 |
| Old Shore Manor Management Company NO.1 Limited | Households | 2001 |
| Old Shore Manor Management Company NO.2 Limited | Households | 2001 |
| One 10 Apartments Management Limited | Households | 2010 |
| One Tone Tackle Ltd | Wholesale & retail | 2022 |
| Oneworldni Limited | Health & social care | 2018 |
| Opus Holdings N.I. Ltd | Financial services | 2024 |
| Orchard Hill (Richhill) Management Limited | Households | 2004 |
| Orchard Meadows Management Company Limited | Households | 2005 |
| Orchard Recruitment Ltd | Administrative & support | 2025 |
| Ortak Property Ltd | Other services | 2026 |
| P G Brown Services Limited | Information & communication | 2015 |
| P Haveron Maintenance Services Ltd | Construction | 2024 |
| P&H Maintenance Ltd | Construction | 2020 |
| Paramount Podiatry Limited | Health & social care | 2020 |
| Parish Community Shop Limited | Wholesale & retail | 2019 |
| Parsons Gate Management Co Ltd | Households | 2017 |
| Pattersonn Limited | Wholesale & retail | 2025 |
| Paul Gilmour Media Ltd | Information & communication | 2025 |
| Paul Harley Plumbing & Heating Ltd | Construction | 2018 |
| Paul James Group Ltd | Other services | 2016 |
| Paul MCR Coaching Ltd | Health & social care | 2024 |
| PBG Ireland Ltd | Hospitality | 2010 |
| PDQ Solutions Ltd | Professional & scientific | 2008 |
| Peak Evolve Coaching Ltd | Arts & recreation | 2023 |
| Peak Performance Engineering Ltd | Manufacturing | 2021 |
| Penrose Property & Investments Ltd | Professional & scientific | 2006 |
| Pepper POT Enterprises Ltd | Administrative & support | 2017 |
| Performr Technologies Ltd | Information & communication | 2022 |
| Peter Strain Limited | Arts & recreation | 2017 |
| Peter Thompson Vans Ltd | Wholesale & retail | 2019 |
| PFT Sales & Marketing Ltd | Hospitality | 2011 |
| Phenomenal Fitness (Newtownabbey) Ltd | Arts & recreation | 2021 |
| Phoenix Premium Drinks Limited | Wholesale & retail | 2011 |
| Phoenix Property Specialist Limited | Real estate | 2021 |
| Pickie Terrace Apartments Management Company Limited | Households | 2007 |
| Pihl Acquisition Limited | Financial services | 2018 |
| Pihl Holdings Limited | Financial services | 2018 |
| PIM Vision Ltd | Information & communication | 2018 |
| Pink Vapes Ltd | Wholesale & retail | 2019 |
| Pinstar Ltd | Wholesale & retail | 2024 |
| Pivotal Building Services (N.I.) Ltd | Construction | 2021 |