| Ovvotech Innovations Ltd | Manufacturing | 2015 |
| Owen Hearty Limited | Transport & logistics | 2014 |
| Owen Mcelroy (NI) Limited | Agriculture & fishing | 1990 |
| Owen ROE Mayobridge Management Limited | Households | 2014 |
| OWR Property Limited | Construction | 2009 |
| Oyster Systems LP | | 2020 |
| O’Donnell Technologies Ltd | Information & communication | 2024 |
| O’Malley International Ltd | Transport & logistics | 2024 |
| P & C Quinn Holdings Ltd | Financial services | 2016 |
| P & D MC Mahon Contracts Limited | Construction | 2008 |
| P & E Contracts Ltd | Construction | 2019 |
| P & E Farming Ltd | Agriculture & fishing | 2021 |
| P & M Developments Ltd | Construction | 2023 |
| P & S Property Rentals Limited | Real estate | 2017 |
| P Black Capital Limited | Professional & scientific | 2024 |
| P Byrne Tractors Ltd | Wholesale & retail | 2013 |
| P J Campbell & Co Ltd | Professional & scientific | 2022 |
| P Lavelle & Sons Limited | Transport & logistics | 1954 |
| P Lutton Limited | Households | 2020 |
| P Mcparland Ltd | Mining & quarrying | 2007 |
| P Murphy Engineering Ltd | Professional & scientific | 2022 |
| P O'Hagan & Associates Limited | Professional & scientific | 2001 |
| P R Plumbing & GAS Services Ltd. | Construction | 2014 |
| P W S Ireland Limited | Manufacturing | 1956 |
| P&J Clerkin Ltd | Agriculture & fishing | 2024 |
| P&M Contracts (IRE) Ltd | Transport & logistics | 2018 |
| P&N Contracts Ltd | Construction | 2023 |
| P&N Prop Ltd | Real estate | 2025 |
| P&P Site Services Limited | Administrative & support | 2020 |
| P&R Contracts Limited | Construction | 2024 |
| P&U Commercials Ltd | Wholesale & retail | 2019 |
| P. Mccrickard Ltd | Construction | 2016 |
| P.A.M. Enterprises Limited | Hospitality | 2017 |
| P.F Mechanical Services (NI) Ltd | Construction | 2023 |
| P.M. Mcginn Ltd | Wholesale & retail | 2012 |
| P2 Putter Grips Ltd | Wholesale & retail | 2023 |
| PA & PA Holdings Limited | Financial services | 2024 |
| Pacamo Limited | Real estate | 2014 |
| Pack Management (NI) Ltd | Households | 2017 |
| Pactec Ltd | Professional & scientific | 2019 |
| Paddy Power's Business Intelligence Ltd | Professional & scientific | 2023 |
| Padon Carpentry Limited | Manufacturing | 2021 |
| Pahvee Ltd | Real estate | 2025 |
| Paintpvc.Com Limited | Construction | 2018 |
| Paintz (NI) Limited | Wholesale & retail | 2006 |
| PAK Kareem Limited | Financial services | 2021 |
| Pamc Engineering Ltd | Professional & scientific | 2025 |
| Panel Mounting Systems & Architectural Components Ltd | Wholesale & retail | 2022 |
| Panprep Ltd | Wholesale & retail | 2025 |
| Para VER Ltd | Health & social care | 2024 |
| Paradigm K Limited | Education | 2023 |
| Paragon Roofing & Guttering Ltd | Construction | 2024 |
| Parcel Fetch Limited | Wholesale & retail | 2022 |
| Park Centre Limited | Wholesale & retail | 2013 |
| Parkcity Import L.P. | | 2017 |
| Parker Green Holdings Limited | Real estate | 2009 |
| Parker Green International Limited | Real estate | 2004 |
| Parkmount Housing Development Management Company Limited | Households | 2007 |
| Parkwall Transport Ltd | Transport & logistics | 2014 |
| Parr Crane Services Limited | Construction | 2024 |
| Passive Window Systems Ltd | Construction | 2012 |
| PAT Casey & Sons Ltd | Construction | 2018 |
| PAT Fleming Motors Ltd | Wholesale & retail | 2019 |
| PAT Hanna Fuels Ltd | Extraterritorial | 2021 |
| PAT Mcmahon Properties Ltd | Real estate | 2020 |
| PAT Rodgers Limited | Construction | 1999 |
| Patricia Cromie Ltd | Wholesale & retail | 2016 |
| Patrician Court Management Company Limited | Households | 2007 |
| Patrick & Brian Rooney Ltd | Construction | 2006 |
| Patrick and Rhona Mccooey Limited | Wholesale & retail | 2015 |
| Patrick Carr Ltd | Transport & logistics | 2016 |
| Patrick F O'Reilly Ltd | Construction | 2015 |
| Patrick Kelly Limited | Wholesale & retail | 2025 |
| Patrick Meehan Limited | Administrative & support | 2015 |
| Patrick Murphy & Sons Energy Ltd | Wholesale & retail | 2025 |
| Patrick Murphy & Sons Limited | Wholesale & retail | 2011 |
| Patrick Thornton Haematology Limited | Health & social care | 2011 |
| Patrycja MC Mahon Limited | Wholesale & retail | 2021 |
| Pats Chippy Ltd | Hospitality | 2023 |
| Patterson & Rocks Solicitors Limited | Professional & scientific | 2012 |
| Patterson Bros Limited | Construction | 2008 |
| Paul Campbell Limited | Professional & scientific | 2015 |
| Paul Close Finance Solutions Ltd | Administrative & support | 2009 |
| Paul Connolly Plant Hire Ltd | Construction | 2021 |
| Paul Feely & Associates Ltd | Professional & scientific | 2023 |
| Paul Gorman Contracts Ltd | Construction | 2016 |
| Paul Hoey Fuels Ltd | Wholesale & retail | 2004 |
| Paul Hughes Hip-View Farm Limited | Agriculture & fishing | 2019 |
| Paul MC Evoy Funeral Directors Ltd | Other services | 2018 |
| Paul Mcevoy Repatriation Ltd | Other services | 2026 |
| Paul Murney Joinery & Building Limited | Manufacturing | 2017 |
| Paul Murray Agri Feeds Limited | Agriculture & fishing | 2013 |
| Paula Universal L.P. | | 2015 |
| PB Trans Ltd | Transport & logistics | 2025 |
| PBA Consulting (NI) Ltd | Professional & scientific | 2014 |
| Pbdfm Limited | Wholesale & retail | 1999 |
| Pbsolar & Biomass (NI) Limited | Manufacturing | 2015 |
| PBT Residential Ltd | Construction | 2023 |
| PC Bricklaying Ltd | Construction | 2017 |
| PC Commercial Developments Ltd | Construction | 2026 |