| Newtownabbey Property Ltd | Real estate | 2024 |
| Newtownabbey Self Storage Ltd | Administrative & support | 2017 |
| Newtownabbey Vehicle Hire Limited | Administrative & support | 2018 |
| NGB Properties NI Ltd | Real estate | 2022 |
| NI Electrical Testing Ltd | Construction | 2025 |
| NI Forestview Farm Ltd | Agriculture & fishing | 2022 |
| NI Health Products Ltd | Wholesale & retail | 2021 |
| NI Housekeeping Ltd | Administrative & support | 2016 |
| NI PAD Ltd | Real estate | 2025 |
| NI Premier Properties Ltd | Real estate | 2025 |
| NI Property Services Ltd | Households | 2023 |
| NI Scaffolding Design Limited | Construction | 2021 |
| NI Security Services Ltd | Administrative & support | 2014 |
| NI Space Office Ltd | Professional & scientific | 2022 |
| NI Standardbred Association | Arts & recreation | 2019 |
| NI WE Care First Ltd | Health & social care | 2026 |
| Niall Devlin Joinery Ltd | Construction | 2018 |
| Nick Bonar Cars Ltd | Wholesale & retail | 2011 |
| Nick Morgan Consulting Ltd | Professional & scientific | 2019 |
| Nigel Farr Consulting Ltd | Information & communication | 2015 |
| NJW Financial Ltd | Financial services | 2022 |
| NMC Property Ventures Ltd | Real estate | 2026 |
| NO Hands Automation Ltd | Information & communication | 2025 |
| NO Time to Clean Limited | Administrative & support | 2016 |
| NO. 37 Ballyholme Road Management Company Limited | Households | 2013 |
| Norglen Development Limited | Construction | 2026 |
| Norso Medical Holdings Limited | Financial services | 2021 |
| Norso Medical Limited | Administrative & support | 2012 |
| North Bay Ventures Ltd | Financial services | 2024 |
| North Star Cleaning Limited | Administrative & support | 2022 |
| North West Motor Factors Limited | Wholesale & retail | 1980 |
| Northern Hot Foods Limited | Hospitality | 2018 |
| Northern Ireland Hospice | Health & social care | 1981 |
| Northern Ireland Hospice (Trading) Limited | Wholesale & retail | 1992 |
| Northern Voyage Ltd | Administrative & support | 2025 |
| Northferry Importers Limited | Wholesale & retail | 1954 |
| Norwest Plant Limited | Manufacturing | 2011 |
| Nourysh Limited | Information & communication | 2026 |
| Nova Kane Logistics Ltd | Wholesale & retail | 2025 |
| Nova Projects Ltd | Professional & scientific | 2025 |
| Novogen Engineering Solutions Ltd | Professional & scientific | 2021 |
| NRF Properties Ltd | Real estate | 2025 |
| Ntdf Limited | Information & communication | 2017 |
| Nushnena Investments Limited | Real estate | 2025 |
| Nutrition Studio Limited | Health & social care | 2023 |
| Nutts Corner Circuit Limited | Arts & recreation | 2008 |
| NVD (N.I.) Limited | Transport & logistics | 2010 |
| NW Automatics Ltd | Administrative & support | 2022 |
| NW Fire Ltd | Public administration | 2012 |
| Nwa-Dy International Ltd | Administrative & support | 2018 |
| Oak C.W.E. Limited | Construction | 2003 |
| Oakdene Services (1925) Ltd | Manufacturing | 2013 |
| Oasis Retail Services Limited | Arts & recreation | 1968 |
| Occupational Safety Services Limited | Extraterritorial | 1966 |
| Oceanic House Limited | Real estate | 2014 |
| OCO Interiors Ltd | Professional & scientific | 2025 |
| Oddwood Lane Ltd | Manufacturing | 2023 |
| OF One Creative Ltd | Professional & scientific | 2025 |
| Ojtaero Limited | Manufacturing | 2024 |
| Old Exchange Court Management Limited | Real estate | 1996 |
| Old Manse Ltd | Financial services | 2021 |
| Olympus Roofing Solutions Limited | Construction | 2025 |
| OM SAI Properties Ltd | Real estate | 2011 |
| Omhy Property Management Ltd | Financial services | 2026 |
| Omnixis Limited | Wholesale & retail | 2023 |
| Omorphia Ltd | Health & social care | 2021 |
| One Electrical Testing Ltd | Extraterritorial | 2025 |
| One Office Products Ltd | Wholesale & retail | 2004 |
| One Three One Fitness Ltd | Arts & recreation | 2025 |
| One-Result Global Ltd | Information & communication | 2013 |
| Ontheedgemedia Ltd | Information & communication | 2025 |
| Open Arms Centre | Other services | 2023 |
| Optimize HR Limited | Professional & scientific | 2021 |
| Optnet Solutions Ltd | Information & communication | 2015 |
| Origin Hair Consultants Limited | Other services | 2012 |
| Original Wellness Ltd | Wholesale & retail | 2023 |
| Ormonde Holdings 2026 Limited | Financial services | 2026 |
| Oscar Mike Media Limited | Information & communication | 2010 |
| Otium Residential Ltd | Real estate | 2026 |
| P K Fitness Limited | Arts & recreation | 2024 |
| Pact NI Properties Ltd | Real estate | 2026 |
| PAL 2024 Consultancy Ltd | Hospitality | 2024 |
| Pallet Centre Limited-The | Manufacturing | 1981 |
| Paperxclips Books Ltd | Wholesale & retail | 2022 |
| Park Lane Management Company (Northern Ireland) Limited | Households | 2009 |
| Pathways 4 Hope NI CIC | Health & social care | 2025 |
| Patton Engineering & SON Limited | Administrative & support | 1974 |
| Paul Darby Plumbing & Heating Ltd | Construction | 2003 |
| Paving 365 Limited | Construction | 2017 |
| PBC Group 1 Ltd | Construction | 2020 |
| PBC Group Ltd | Construction | 2019 |
| PCL Consultancy Limited | Wholesale & retail | 2023 |
| Pdel Limited | Professional & scientific | 2014 |
| PE3 Pipeline Services Limited | Construction | 2009 |
| Peeples Wholesale Ltd | Wholesale & retail | 2022 |
| PEM Mechanical (NI) Limited | Administrative & support | 2015 |
| Pensio Property Ltd | Real estate | 2022 |
| Performance Analysed Limited | Arts & recreation | 2021 |
| Performance Systems Ltd | Manufacturing | 2022 |
| Perpetual Consulting Ltd | Professional & scientific | 2024 |