| Nyweb AS | Education | 2009 |
| Nå AI AS | Professional & scientific | 2025 |
| Nødings Delikatesse AS | Manufacturing | 2004 |
| Nøsted & AS | Manufacturing | 1939 |
| Nøsted Eiendom I AS | Real estate | 2008 |
| Nøsted Eiendom II AS | Real estate | 2008 |
| O. Edland AS | Construction | 2013 |
| O.A.N Holding AS | Administrative & support | 2005 |
| Oakland Home AS | Wholesale & retail | 2023 |
| Oakland Møbler Bærum AS | Wholesale & retail | 2023 |
| Oakland Møbler Fredrikstad AS | Wholesale & retail | 2023 |
| Oakland Møbler Jærhagen AS | Wholesale & retail | 2026 |
| Oakland Møbler Søgne AS | Wholesale & retail | 2026 |
| Oakland Møbler Trondheim AS | Wholesale & retail | 2022 |
| Oas Bil Og Båtservice AS | Administrative & support | 2016 |
| Oasen Skole Mandal AS | Education | 2013 |
| Ocean Equity AS | | 2021 |
| Oceangate Norway AS | Real estate | 2014 |
| Odegabs AS | Real estate | 2025 |
| Odh Retail AS | Wholesale & retail | 2025 |
| Oeg Holding AS | Real estate | 2016 |
| Oei Holding AS | Real estate | 2016 |
| Of Capital AS | | 2021 |
| Oh Eiendomsutvikling AS | Real estate | 2008 |
| Oksevollen 14 AS | Real estate | 2024 |
| Olav Solberg Holding AS | Health & social care | 2024 |
| Olivia Capital AS | Financial services | 2014 |
| Olivias Hus Mandal AS | Wholesale & retail | 2018 |
| Olka Invest AS | Real estate | 2019 |
| Oluf Lohne | Real estate | 1848 |
| Oluf Lohne Eiendom AS | Real estate | 2024 |
| Omhinvest AS | | 2025 |
| Omland Invest AS | Financial services | 2005 |
| Omre Næringspark AS | Real estate | 2012 |
| Online Growth AS | Information & communication | 2026 |
| Ophaug Eiendom & Invest AS | Real estate | 2014 |
| Opk AS | Professional & scientific | 2018 |
| Opplev Hald AS | Real estate | 2023 |
| Optimaliser Din Helse AS | Wholesale & retail | 2024 |
| Oriental Market AS | Wholesale & retail | 2020 |
| Orissa AS | Real estate | 2014 |
| Orizon AS | | 2025 |
| Osak Eiendom AS | Construction | 2017 |
| Osk Eiendom 1 AS | Real estate | 1998 |
| Osk Invest AS | Real estate | 2007 |
| Oskar Kaaløy AS | Construction | 2012 |
| Ossia AS | Arts & recreation | 2008 |
| Ovata AS | Real estate | 1996 |
| P. E. Holding AS | Construction | 2014 |
| P. Lindberg Nuf | Wholesale & retail | 2013 |
| P.A Klev Eftf. AS | Construction | 2014 |
| P.A.K Saltverket 18 AS | Construction | 2007 |
| P.E. Gaarud AS | Construction | 2018 |
| P.P. Holding AS | | 2024 |
| P.S. Holding AS | Real estate | 2005 |
| P.T Thomassen AS | Transport & logistics | 2020 |
| Pal Services AS | Information & communication | 2003 |
| Paod AS | Real estate | 2015 |
| Pareka AS | Professional & scientific | 2019 |
| Parfymeri Sør AS | Wholesale & retail | 2022 |
| Parkgaten 8 AS | Real estate | 2006 |
| Parramatta AS | | 2018 |
| Pass the Salt AS | Professional & scientific | 2020 |
| Paul J Loland AS | Construction | 2009 |
| Paulsbo Invest AS | | 2025 |
| Paulsen Designstudio AS | Arts & recreation | 2023 |
| Pav Holding AS | Professional & scientific | 2013 |
| Pedersen Klimakomfort AS | Construction | 2013 |
| Pekis Bygg AS | Professional & scientific | 2005 |
| Pekriwa Holding AS | Real estate | 2005 |
| Penrose Solutions AS | Information & communication | 2026 |
| Pepe Utvikling AS | Manufacturing | 2005 |
| Per Ivans Catering AS | Hospitality | 2017 |
| Per Kristian Wathne Ans | | 1995 |
| Per Myklebost AS | Health & social care | 2025 |
| Peri Consulting AS | Professional & scientific | 2021 |
| Persneset Utvikling AS | Real estate | 2025 |
| Pik Pobedy AS | Professional & scientific | 2018 |
| Pilatesbutikken AS | Wholesale & retail | 2025 |
| Pimko AS | Professional & scientific | 2024 |
| Ping Design AS | Professional & scientific | 2016 |
| Pinnebyen Dagligvare Og Handel AS | Wholesale & retail | 2025 |
| Piren Energisentral AS | Energy | 2004 |
| Piren LL I AS | Real estate | 2003 |
| Piren Partner AS | Education | 2005 |
| Piren Pub & Tall AS | Administrative & support | 2018 |
| PJL Eiendom AS | Real estate | 2008 |
| PJL Holding AS | Construction | 2009 |
| PL Invest AS | Real estate | 2005 |
| PL Service AS | Administrative & support | 2025 |
| Plantech AS | Financial services | 2005 |
| Plaremo AS | Professional & scientific | 2023 |
| Pluskvamperfektum Invest AS | | 2022 |
| PMN Holding AS | Professional & scientific | 2005 |
| PN Lagerhotell AS | Real estate | 2009 |
| PN Prosjekt AS | Wholesale & retail | 1997 |
| Pointer Invest AS | | 2019 |
| Powerdamp AS | Wholesale & retail | 2019 |
| Preg Barnehager Ime AS | Education | 2022 |
| Prepro Service AS | Professional & scientific | 2018 |