| NAS Logistics (NI) Ltd | Other services | 2020 |
| NB Enterprises Ltd | Wholesale & retail | 2019 |
| NB Recycling Limited | Manufacturing | 2016 |
| NDB Medical Services Ltd | Health & social care | 2023 |
| Neill Technology Limited | Information & communication | 2021 |
| New Bridge Property Group Limited | Construction | 2023 |
| New Street Property Management Ltd | Extraterritorial | 2007 |
| Newell Contracts Limited | Construction | 2018 |
| Newman Consulting Ltd | Professional & scientific | 2025 |
| Newpark Developments (Management Company) Ltd. | Households | 2015 |
| Next Steps Consultancy Limited | Construction | 2021 |
| NI Digital Solutions Limited | Information & communication | 2011 |
| NI Wind Options Limited | Energy | 2013 |
| Niblock Oaks Land Management Limited | Extraterritorial | 2006 |
| NIDOT2DOT Ltd | Health & social care | 2026 |
| Nigel Cinnamon Consulting Ltd | Professional & scientific | 2023 |
| Nigrum Domum Limited | Real estate | 2025 |
| NK Contract Services Limited | Construction | 2025 |
| Norman Watt & SON Limited | Wholesale & retail | 2011 |
| North Lodge Management Carrickfergus Ltd | Extraterritorial | 2004 |
| North Square Management Company Ltd | Households | 2007 |
| North Ulster Car Club Limited - the. | Other services | 1978 |
| Northshore House Ltd | Construction | 2019 |
| Nottinghill Management Company Limited | Households | 2014 |
| Nowdoctor Ltd. | Information & communication | 2022 |
| O'Cahan Place Land Management Ltd | Extraterritorial | 2003 |
| O'Hara's Bakery Limited | Manufacturing | 2019 |
| O'Sullivan Macfarlane Ltd | Professional & scientific | 2016 |
| Oakleigh Park Management Company Limited | Extraterritorial | 1999 |
| Oakwood Boarding Ltd | Other services | 2025 |
| Oakwood Property Management Cookstown Ltd | Extraterritorial | 2007 |
| Obins Street Land Management Ltd | Extraterritorial | 2006 |
| Ocean Native Ltd | Wholesale & retail | 2024 |
| Okotech Limited | Information & communication | 2011 |
| Old Clare Grange Management Ltd | Extraterritorial | 2014 |
| Old Forde Apartments Ltd | Extraterritorial | 2002 |
| Old School House Developments Ltd | Extraterritorial | 2005 |
| Old School Mews (Glenavy) Management Ltd | Households | 2017 |
| Old Shore View Management Limited | Extraterritorial | 2007 |
| Old Steeple Management Ltd | Extraterritorial | 2005 |
| Old Turn Court Management Ltd | Extraterritorial | 2008 |
| Olikat Limited | Professional & scientific | 2006 |
| Ollar Developments Limited | Construction | 2023 |
| Ollar Property Limited | Real estate | 2021 |
| Ollar Support Services Ltd | Administrative & support | 2013 |
| Ollar Valley Management Company Limited | Households | 2018 |
| Oloo Kitchens Limited | Manufacturing | 2016 |
| Omada Subs Ltd | Hospitality | 2019 |
| ON SET Response Ltd | Health & social care | 2021 |
| One Hair & Beauty Spa Ltd | Other services | 2021 |
| One Step Insulation Limited | Construction | 2014 |
| Onemoretuneni Ltd | Manufacturing | 2024 |
| OOH & AAH Cookies Ltd | Wholesale & retail | 2023 |
| Open Space Developments Limited | Households | 2017 |
| Optimize-Ni Ltd | Health & social care | 2017 |
| Orby Green Management Company (NO.1) Limited | Real estate | 2000 |
| Orchys Ltd | Information & communication | 2004 |
| Organisational Design Ltd | Professional & scientific | 2019 |
| Oriel Court Apartments Limited | Extraterritorial | 1984 |
| Oriel Road Apartments Ltd | Extraterritorial | 2008 |
| Orpins Mill Management Ltd | Households | 2006 |
| Orritor Management Limited | Extraterritorial | 2001 |
| Oura Training Ltd | Health & social care | 2025 |
| Overdrive Productions Limited | Arts & recreation | 2025 |
| Oyster Yard Management Ltd - the | Extraterritorial | 2005 |
| P.J Consultants Ltd | Professional & scientific | 2020 |
| P.R. Lagan Limited | Wholesale & retail | 2017 |
| Palmerston Court Belfast Limited | Households | 2006 |
| Papa Food Ltd | Hospitality | 2024 |
| Paper Mill Land Management Ltd | Households | 2022 |
| Papermill Road Limited | Real estate | 2025 |
| Paratus Volare Limited | Real estate | 2026 |
| Parenergy Ltd | Manufacturing | 2021 |
| Park Avenue Heights Management Co Ltd | Households | 2018 |
| Park Lane Downpatrick Management Ltd | Households | 2019 |
| Park Lane Land Management Ltd | Extraterritorial | 2002 |
| Parkgate 632 Limited | Financial services | 2020 |
| Parkgate Estates N.I. | Real estate | 2004 |
| Parkgate Meadow Management Ltd | Extraterritorial | 2013 |
| Parkmount Crescent Property Management Company Limited | Extraterritorial | 2009 |
| Parkview (Ballyclare) Management Company Limited | Extraterritorial | 2005 |
| Parkwatch Management Limited | Extraterritorial | 1997 |
| Pbabni Ltd | Health & social care | 2026 |
| PC Building Contracts Ltd | Construction | 2024 |
| Pdik Ltd | Hospitality | 2019 |
| Peacock Living Ltd | Real estate | 2025 |
| Peacock Living Spaces Ltd | Real estate | 2025 |
| Pembrooke Apartments (NO.2) Limited | Households | 1982 |
| Penjoe Ltd | Financial services | 2026 |
| PEP Research NI Limited | Professional & scientific | 2026 |
| Periscope Global Solutions Limited | Professional & scientific | 2023 |
| Petticrew Park Land Management Ltd | Households | 2021 |
| PFM (NI) Limited | Construction | 2013 |
| PGC Group Ltd | Real estate | 2025 |
| Philip Holland Cars | Wholesale & retail | 2009 |
| PIN Point Distribution Ltd | Wholesale & retail | 2024 |
| Pipejointsystem UK Ltd | Construction | 2013 |
| Plantation Mews Management Company Limited | Households | 2020 |
| PMD Plumbing and Heating Services Limited | Construction | 2025 |
| Portland Hall Management Limited | Households | 2014 |