| Nor Frukt AS | Wholesale & retail | 2017 |
| Noraks AS | Real estate | 2001 |
| Nordmørsposten AS | Information & communication | 2024 |
| Nordre Follo Tannlegesenter AS | Health & social care | 2021 |
| Nordstrand Totalentreprenør AS | Construction | 2018 |
| Nortronic AS | Wholesale & retail | 1995 |
| Nye Bølger AS | Wholesale & retail | 2014 |
| Nye Mosseveien 258 B AS | Real estate | 2022 |
| Object Factory AS | | 2021 |
| Obliteration Da | Arts & recreation | 2010 |
| Olufine AS | Professional & scientific | 2005 |
| Omega Security AS | Administrative & support | 2025 |
| Omnitrade AS | Wholesale & retail | 1984 |
| Omrygh AS | Health & social care | 2022 |
| On Track Consult AS | Professional & scientific | 2001 |
| Opius Holding AS | | 2025 |
| Oppegård Bilsalg AS | Wholesale & retail | 2022 |
| Oppegård Eiendomsmegling AS | Real estate | 2010 |
| Opplyst Elektro AS | Administrative & support | 2017 |
| Orion Postordre Norge AS | Wholesale & retail | 1994 |
| OS2 Consulting AS | Professional & scientific | 2013 |
| Oslo Auto AS | Wholesale & retail | 2020 |
| Oslo Classic AS | Wholesale & retail | 2013 |
| Oslonature AS | Administrative & support | 2025 |
| Ospeholmen Utvikling AS | Administrative & support | 2003 |
| Panda Invest AS | | 2025 |
| Paus Film AS | Information & communication | 2021 |
| Penn Og Pensel AS | | 1990 |
| Peppernexpress AS | Hospitality | 2022 |
| Per-Ove Brekke Holding AS | | 2022 |
| PER4M AS | Professional & scientific | 2021 |
| Perfekt Bygg AS | Real estate | 2002 |
| Perfekt Design & Bygg AS | Administrative & support | 2025 |
| PFT Invest AS | Real estate | 2016 |
| PG Holding AS | Real estate | 2005 |
| Pied Piper Holding AS | Financial services | 2017 |
| Pilestredet Park 18 Eiendom AS | Wholesale & retail | 2012 |
| Pine-Headland AS | Financial services | 2008 |
| Poleland AS | | 2023 |
| Prater AS | Information & communication | 1996 |
| Prater Eiendom AS | Real estate | 2020 |
| Prater Holding AS | Information & communication | 2009 |
| Precious Pet Da | Wholesale & retail | 2021 |
| Prenax AB Nuf | Information & communication | 2007 |
| Pressalit AS | Wholesale & retail | 2008 |
| Printz Bergquist AS | | 2007 |
| Prmp Holding AS | | 2025 |
| Proscale Consulting AS | Professional & scientific | 2026 |
| Prosenior AS | Other services | 2017 |
| Prosjektassistanse AS | Professional & scientific | 2013 |
| Prosperis AS | Health & social care | 2026 |
| Prune AS | Wholesale & retail | 2021 |
| PS Prosjekt AS | Financial services | 2006 |
| Pti Nordic AS | Professional & scientific | 2021 |
| Puls Kantor AS | Arts & recreation | 2016 |
| Pustut AS | Information & communication | 2005 |
| Putten Kapital AS | | 2020 |
| PWW Invest AS | | 2021 |
| Pyx AS | Financial services | 2005 |
| Pål Tonga Holding AS | Financial services | 2012 |
| Pømm Holding AS | | 2026 |
| Ralokan AS | Information & communication | 2022 |
| Real Management AS | Professional & scientific | 2019 |
| Reflexivity AS | Health & social care | 2020 |
| Regnestav AS | | 2017 |
| Regor Invest AS | | 2021 |
| Reiersen Entreprenør AS | Construction | 1995 |
| Reiersen Holding AS | Construction | 2005 |
| Rekdahl Invest AS | Real estate | 2018 |
| Relieff AS | Professional & scientific | 2019 |
| Relieff Holding AS | Real estate | 2019 |
| Renets AS | Professional & scientific | 2017 |
| Rentatech AS | Information & communication | 2020 |
| Repål Holding AS | Financial services | 2006 |
| Ressurs Gruppen AS | Real estate | 2001 |
| Rett & Slett Tyrhaug AS | Construction | 2017 |
| Ricco AS | Professional & scientific | 1988 |
| Rikeåsen Barnehage SA | Education | 1995 |
| Rinaldi AS | Wholesale & retail | 2021 |
| Ringwald &Co AS | | 2025 |
| Riwieri Holding AS | | 2021 |
| RKP AS | Wholesale & retail | 2005 |
| Robert Tandberg AS | Professional & scientific | 2016 |
| Roeddami Da | Professional & scientific | 2026 |
| Rogd AS | Administrative & support | 1997 |
| Rogd Da | Administrative & support | 2002 |
| Rosenholmveien 45 AS | Real estate | 2010 |
| Rubarb AS | Information & communication | 2023 |
| Rytter-Jager Invest AS | | 2022 |
| Røed Inwest AS | Real estate | 2007 |
| Rørhjelp AS | Construction | 2011 |
| Rørmann AS | Construction | 2026 |
| S-K Invest AS | Wholesale & retail | 2019 |
| Saastad Consulting AS | Information & communication | 2026 |
| Sacha Holding AS | | 2025 |
| Saeme Tolk Og Oversetterkontor Da | Professional & scientific | 1994 |
| Samfunnshuset Eiendom AS | Real estate | 2007 |
| Samfunnshuset Kolbotn SA | Real estate | 1956 |
| Sanderud Technologies AS | Financial services | 2017 |
| Sandjoh AS | | 2021 |