| Norfish (NI) Limited | Extraterritorial | 1998 |
| North Coast Surgery Limited | Health & social care | 2023 |
| North West Builders (Derry) Limited | Construction | 1987 |
| North West Carnival Initiative | Other services | 2017 |
| North West Migrants Forum | Hospitality | 2019 |
| North West Urology Associates Limited | Health & social care | 2022 |
| Northern Memorials Limited | Other services | 2024 |
| Northern Powerforce Developments Ltd | Real estate | 2024 |
| Northland Construction Limited | Construction | 2018 |
| Northland Properties Limited | Real estate | 2007 |
| Northside Butchers Ltd | Wholesale & retail | 2011 |
| Northwest Commissioning Services Ltd | Construction | 2023 |
| Northwest Orthovet Limited | Professional & scientific | 2023 |
| Nova Nails & Aesthetics Ltd | Other services | 2026 |
| NPF Holdco Ltd | Financial services | 2024 |
| NU Look Blinds Ltd | Wholesale & retail | 2021 |
| NUA Cosmetics Ltd | Wholesale & retail | 2024 |
| Number 19 Craft and Design C.I.C. | Arts & recreation | 2015 |
| NW Content Studio Ltd | Professional & scientific | 2024 |
| NW Plumbing and Heating Ltd | Construction | 2022 |
| Nwdc Ltd | Administrative & support | 2015 |
| O'Connor Formwork Ltd | Construction | 2021 |
| O'Donnell Commercials (N.I.) Ltd | Wholesale & retail | 2020 |
| O'Donnell Properties (Ireland) Limited | Construction | 2006 |
| O'Driscoll Educational & Child Psychology Ltd | Education | 2023 |
| O'Hara Joinery Limited | Construction | 2014 |
| O'Kane and Mclaughlin (Builders N.I.) Limited | Construction | 2014 |
| O'Kane's Liquor Stores Limited | Wholesale & retail | 1976 |
| O'Neill Bros. Master Joiners Ltd | Manufacturing | 2011 |
| Oak Drive Company Limited | Hospitality | 2023 |
| Oak Grove Cabins Ltd | Manufacturing | 2005 |
| Oak Properties and Management Ltd | Real estate | 2022 |
| Oak Safety and Training Limited | Professional & scientific | 2025 |
| Oakborn Ltd | Hospitality | 2022 |
| Oakcliff Developments Limited | Real estate | 2000 |
| Oakleaf Autos Ltd | Wholesale & retail | 2025 |
| Oakmont Property Management Ltd | Real estate | 2024 |
| OBF Equipment Limited | Manufacturing | 2023 |
| OBG Fabrications Limited | Manufacturing | 2020 |
| Ocean Tiles and Bathrooms Ltd | Construction | 2017 |
| Oconee Ltd | Real estate | 2023 |
| Ocoylej Ltd | Real estate | 2018 |
| Octoberstone Faithworks Ltd | Administrative & support | 2017 |
| Od's Garage Ltd | Manufacturing | 2019 |
| ODK Properties Limited | Construction | 2013 |
| OFC Ireland Ltd | Wholesale & retail | 2003 |
| Ofca Debt Solutions Ltd | Professional & scientific | 2012 |
| Ogma Safety Ltd | Other services | 2016 |
| Old Bridge Pictures Ltd | Information & communication | 2025 |
| Old Bridge Properties Limited | Real estate | 2019 |
| Older People North-West | Health & social care | 1995 |
| One Crawford Square Ltd | Health & social care | 2023 |
| One More Bounce Ltd | Wholesale & retail | 2025 |
| One Stop Shop Derry Ltd | Wholesale & retail | 2025 |
| Onemore Health & Fitness Limited | Other services | 2025 |
| Onesource Virtual (UK) Limited | Information & communication | 2015 |
| ONS Enterprises Limited | Wholesale & retail | 2019 |
| OQ Anaesthesia Ltd | Health & social care | 2025 |
| Osta Cafe & Guesthouse Ltd | Hospitality | 2024 |
| Otfm Help Limited | Financial services | 2017 |
| Outerwest Foyleside Local Growth Limited | Administrative & support | 2023 |
| P Doherty Ecosmart Fuels NI Limited | Other services | 2025 |
| P Gill Transport Limited | Transport & logistics | 2019 |
| P Mcveigh Limited | Construction | 2017 |
| P.J.D. Contracts Limited | Construction | 1997 |
| Pains Fireworks (Ireland) Ltd | Arts & recreation | 2023 |
| Panalp Limited | Administrative & support | 2004 |
| PAP Hire Limited | Administrative & support | 2025 |
| Park Moore Limited | Health & social care | 2012 |
| Park Street Projects Ltd | Real estate | 2020 |
| Parkallion Limited | Hospitality | 2023 |
| Parkhouse Business Services Limited | Administrative & support | 2024 |
| Parkworkz Limited | Professional & scientific | 2025 |
| Party Warehouse Ltd | Wholesale & retail | 2005 |
| Passive House NI Limited | Construction | 2014 |
| PAT D Electrical Ltd | Construction | 2025 |
| PAT Finucane Centre Ltd - the | Health & social care | 2008 |
| Patral Limited | Professional & scientific | 2015 |
| Paul Casey Music Limited | Arts & recreation | 2002 |
| Paul Green Accountancy and Taxation Limited | Professional & scientific | 2006 |
| Pauline Elliott Estate Agents Ltd | Real estate | 2021 |
| Pavo the Window Doctor Limited | Wholesale & retail | 2023 |
| PB Amusements Limited | Arts & recreation | 2011 |
| PB Cloud Consulting Limited | Information & communication | 2022 |
| PC Partitions Ltd | Construction | 2018 |
| PCA Build (N.I.) Limited | Construction | 2023 |
| Pcfa Optom Ltd | Health & social care | 2024 |
| PD Ebrington Limited | Financial services | 2022 |
| PD Electrical and Management Limited | Construction | 2022 |
| Peaball Academy Ltd | Arts & recreation | 2025 |
| Peaball Creative Limited | Arts & recreation | 2023 |
| Peacebridge Ltd | Real estate | 2012 |
| Pennyburn Industrial Estate (Management Company) Limited | Real estate | 2005 |
| Peter O'Brien Homes Limited | Construction | 2000 |
| Peter Wallace Consulting Limited | Professional & scientific | 2016 |
| Petworld Stores LK Ltd | Wholesale & retail | 2025 |
| PFL Developments Ltd | Real estate | 2018 |
| PH Fireplaces & Granite Limited | Construction | 2017 |
| PHE Plumbing & Engineering Systems Ltd | | 2005 |
| Phoenix Engineering Works Limited | Professional & scientific | 2020 |