| Optalbe Restaurantdrift AS | Hospitality | 2008 |
| Optiker Leborg 2 AS | Wholesale & retail | 2008 |
| Opulentia AS | | 2024 |
| Orbify.Ai AS | Information & communication | 2021 |
| Orbify.Solutions AS | | 1998 |
| Orbify.Technology AS | Information & communication | 2020 |
| Orchestrate Holding AS | | 2026 |
| Organic Beauty AS | Other services | 2019 |
| Origo Eiendom Horten AS | Real estate | 2016 |
| Orion Holding AS | Real estate | 2005 |
| Orion Revisjon AS | Professional & scientific | 2016 |
| Oseberg AS | Real estate | 2010 |
| Oseberg Eiendom AS | Real estate | 2012 |
| Oseberg Holding AS | Real estate | 2010 |
| Oseberget Eiendom AS | Real estate | 1916 |
| Ostuni Holding AS | | 2025 |
| Otg Invest AS | | 2020 |
| Otra Invest AS | Financial services | 2006 |
| Over Stokk Og Stein Transport AS | Transport & logistics | 2014 |
| Overlock Development AS | Information & communication | 2024 |
| Overvannsteknikk AS | Wholesale & retail | 2019 |
| Owl & Fox AS | Information & communication | 2024 |
| P Abrahamsen Transport AS | Transport & logistics | 1948 |
| Paal-Andre Schwital AS | Professional & scientific | 1997 |
| Padel Tønsberg Drift AS | Arts & recreation | 2021 |
| Paereli Invest AS | | 2023 |
| Pah Kapital AS | | 2026 |
| Pal AS | Administrative & support | 2019 |
| Palette AS | Wholesale & retail | 2025 |
| Pallaska AS | Hospitality | 2014 |
| Palmako Norge AS | Wholesale & retail | 2017 |
| Palmer Agentur AS | Wholesale & retail | 2022 |
| Panorama AS | Real estate | 2018 |
| Papa Holding AS | Financial services | 2016 |
| Parasollfix AS | Wholesale & retail | 2020 |
| Parente Invest AS | Real estate | 2016 |
| Parero AS | Real estate | 2016 |
| Parinder AS | Hospitality | 2010 |
| Parkmiljø AS | Wholesale & retail | 2014 |
| Parkterrassen Utleie AS | Real estate | 1999 |
| Pashn AS | Education | 2017 |
| Passer Group AS | Manufacturing | 2016 |
| Passer Marine AS | Professional & scientific | 2008 |
| Passer Products AS | Manufacturing | 2005 |
| Passion Invest AS | Real estate | 2014 |
| Pataljanis Dogshow Products AS | Wholesale & retail | 2021 |
| Patrick Catering & Event AS | Hospitality | 2024 |
| Patrick Jensen AS | Construction | 2016 |
| Pavels Consulting AS | Professional & scientific | 2022 |
| PB Eiendom AS | Real estate | 2019 |
| PBW Invest AS | | 2022 |
| PC Holm Holding AS | | 2025 |
| PCK AS | Information & communication | 2025 |
| PD Utvikling AS | Real estate | 2021 |
| PDV Bygg AS | Construction | 2006 |
| Pebo AS | Real estate | 2011 |
| Pec Elektro Sandefjord AS | Construction | 2006 |
| Pedalgarasjen AS | Other services | 2018 |
| Peder Bogens Gate 4 B Ans | Real estate | 2000 |
| Peder Bogensgate 10 AS | Real estate | 2011 |
| Pekama AS | Professional & scientific | 2005 |
| Pendula Interiør AS | Wholesale & retail | 1994 |
| Peplar AS | Hospitality | 2014 |
| Pepper Norge AS | Wholesale & retail | 2013 |
| Pepsan Invest AS | Hospitality | 2013 |
| Peptide Biotech AS | Professional & scientific | 2024 |
| Per Abrahamsen AS | Construction | 1999 |
| Per Dagfinn Thorsen AS | Construction | 2022 |
| Per's Kjøkken AS | Manufacturing | 1965 |
| Pere AS | Real estate | 2005 |
| Perfekt Pizza AS | Hospitality | 2023 |
| Perio - Klinikken AS | Health & social care | 2018 |
| Perio Eiendom AS | Real estate | 2019 |
| Perio Holding AS | Health & social care | 2018 |
| Pesom Invest AS | Real estate | 2014 |
| Peter Grøns Gate 2A AS | Real estate | 2022 |
| Peternity AS | Wholesale & retail | 2023 |
| Petro Holding AS | | 2025 |
| Petrotest Bitumen AS | Professional & scientific | 2025 |
| Petrotest Fuel & Chemicals AS | Professional & scientific | 2025 |
| Petter Mathisen AS | Financial services | 2005 |
| Pga Maskin AS | Construction | 2025 |
| Pharmore AS | Professional & scientific | 1996 |
| Pharmreg Consulting Ans | Professional & scientific | 2003 |
| Phila Invest AS | Real estate | 2010 |
| PHM Invest Sandefjord AS | | 2020 |
| Pi-Pa Gearbox AS | Professional & scientific | 2022 |
| Pianopedagogene Da | Education | 2024 |
| Pias Blomster AS | Wholesale & retail | 2010 |
| Pico Holding AS | Financial services | 2013 |
| Piero Products AS | Professional & scientific | 2018 |
| Pikatsju of Gandalf AS | Financial services | 2020 |
| Pilot Flight Academy AS | Education | 2007 |
| Pina AS | Real estate | 2006 |
| Pindena AS | Information & communication | 2012 |
| Pindsle Apotek AS | Wholesale & retail | 2007 |
| Pindsle Auto AS | Other services | 2012 |
| Pindsle Bolig 2 AS | Real estate | 2008 |
| Pindsle Bolig AS | Real estate | 2016 |
| Pindsle Eiendomsutvikling AS | Real estate | 2005 |