| OK Parking Ltd | Transport & logistics | 2015 |
| OK Products (NI) Ltd | Wholesale & retail | 2024 |
| OK Services Bellaghy Ltd | Wholesale & retail | 2025 |
| Okko Health Ireland Trading Ltd | Health & social care | 2021 |
| Okmac Solutions Ltd | Information & communication | 2026 |
| Olbm Ltd | Financial services | 2025 |
| Old Wells Wood Limited | Real estate | 2019 |
| Old Wood Consulting Limited | Professional & scientific | 2024 |
| Oldtown Developments Ltd | Construction | 2004 |
| Olflcs Ltd | Financial services | 2025 |
| ON the Diamond Ltd | Wholesale & retail | 2022 |
| Oncce Holdings Limited | Financial services | 2022 |
| Oncce Limited | Construction | 2016 |
| Orchard Installation Ltd | Construction | 2020 |
| Ormonde Machinery (NI) Ltd | Wholesale & retail | 2004 |
| Orrecon Ltd | Construction | 2020 |
| Overload Magherafelt Ltd | Hospitality | 2021 |
| Ovrsee Ltd | Information & communication | 2026 |
| O’Kanes Retail Limited | Other services | 2018 |
| P & a Mcguigan Limited | Administrative & support | 2003 |
| P & BOC (Holdings) Limited | Financial services | 2019 |
| P & D Ventilation Services Ltd | Construction | 2010 |
| P Davidson Contracts Ltd | Construction | 2023 |
| P Diamond Contracts Ltd | Construction | 2016 |
| P F Contracts Ltd | Construction | 1998 |
| P Keenan Quarries Limited | Mining & quarrying | 2023 |
| P Keenan Roads Limited | Mining & quarrying | 2023 |
| P Scullion Construction and Canal Lockgates Limited | Construction | 2000 |
| Paddy Campbell Interiors Limited | Professional & scientific | 2024 |
| Palm Pouch Limited | Wholesale & retail | 2025 |
| Pann 7 Ltd | Financial services | 2022 |
| Parkanaur Construction Limited | Construction | 2019 |
| Parkmore Roofing Ltd | Construction | 2016 |
| Parkmore Taxis Ltd | Transport & logistics | 2019 |
| Patrick Crozier Limited | Wholesale & retail | 2025 |
| Patrick Keenan Holdings | Mining & quarrying | 2025 |
| Patron Coffee Limited | Manufacturing | 2022 |
| Paul Mcgrogan Contracts Ltd | Construction | 2001 |
| PB Bricklaying Ltd | Construction | 2026 |
| PB Paving Contracts Limited | Construction | 2017 |
| Pdca Engineering Solutions Ltd | Professional & scientific | 2018 |
| Peadar DEE Results Ltd | Education | 2023 |
| Pearl & Grace Online Ltd | Wholesale & retail | 2023 |
| Pearl & Grace Retail Ltd | Wholesale & retail | 2023 |
| Pearl Leisure Enterprises Ltd | Arts & recreation | 2025 |
| Pedyxgs Limited | Wholesale & retail | 2025 |
| Pekk Holdings Ltd | Construction | 2022 |
| PFC Transport Ltd | Transport & logistics | 2010 |
| PGF Computer Solutions Ltd | Other services | 2016 |
| Phoenix Emerald Holdings Limited | Financial services | 2026 |
| Pine Crescent Company Limited | Administrative & support | 2016 |
| Pine Heights Company Limited | Professional & scientific | 2016 |
| Piney Way Enterprises Limited | Other services | 2025 |
| Ping Music School Limited | Education | 2018 |
| Pinnacle Developments and Construction Limited | Construction | 2024 |
| PJS Auto Engineering Ltd | Manufacturing | 2012 |
| PJT Power Ltd. | Energy | 2015 |
| PK Farm Ltd | Agriculture & fishing | 2017 |
| PK Packing Limited | Administrative & support | 2010 |
| Plum Avenue Company Limited | Real estate | 2022 |
| PM Digital Design Limited | Wholesale & retail | 2022 |
| PMC Bodies Limited | Professional & scientific | 2022 |
| PMC Homes Ltd | Financial services | 2022 |
| Pmcc Joinery Ltd | Construction | 2018 |
| Pmcg Companies Ltd | Administrative & support | 2016 |
| PMD Contracts Limited | Construction | 2002 |
| PMF Contracts Ltd | Construction | 2025 |
| PMG Construction Ltd | Professional & scientific | 2015 |
| PMG Trading Limited | Agriculture & fishing | 2013 |
| PMK Motors Limited | Wholesale & retail | 2018 |
| Pocket Angler Ltd | Information & communication | 2021 |
| POH Building Contracts Ltd | Construction | 2024 |
| Point 2 Group Ltd | Financial services | 2026 |
| Point 2 Investments Ltd | Households | 2023 |
| Point 2 Mortgages Ltd | Financial services | 2015 |
| Poppy Heights Limited | Extraterritorial | 2026 |
| Potamihan Ltd | Wholesale & retail | 2025 |
| Powermax Engineering Ltd | Manufacturing | 2013 |
| Precast Concrete Services Ltd | Professional & scientific | 2019 |
| Precision Joinery Contracts Ltd | Construction | 2019 |
| Premier Electrics Limited | Construction | 1998 |
| Premier Music Ltd | Information & communication | 2007 |
| Premier Woodlands Limited | Agriculture & fishing | 1992 |
| Priestown Consultancy Ltd | Administrative & support | 2024 |
| Prime Beauty (N.I.) Limited | Extraterritorial | 2017 |
| Prism AM Limited | Real estate | 2026 |
| Process Recovery Ltd | Arts & recreation | 2025 |
| Procure Equipment Ireland Ltd | Wholesale & retail | 2000 |
| Promah Ltd | Real estate | 2019 |
| Prospect Community Ltd | Professional & scientific | 2021 |
| Protec Technologies Limited | Wholesale & retail | 2021 |
| Protx (N.I.) Ltd | Manufacturing | 2011 |
| PT Auto Electrics Limited | Manufacturing | 2014 |
| Purposely Made Ltd | Manufacturing | 2005 |
| PVM Joinery Ltd | Construction | 2026 |
| Quinn & Heron Solicitors Limited | Professional & scientific | 2016 |
| Quinn Computing Limited | Information & communication | 1999 |
| Quinn Tiling Limited | Construction | 2009 |
| R & D Retail Limited | Wholesale & retail | 2018 |
| R & E Contractors Ltd | Construction | 2024 |