| Orbitarena AS | Professional & scientific | 1968 |
| Orbitarena Kompetanse AS | Professional & scientific | 2021 |
| Oslo Service AS | Administrative & support | 2023 |
| Oslo-Byggentreprenør AS | Real estate | 2018 |
| Ovid Medical Ans | Wholesale & retail | 2004 |
| Ovidia AS | Real estate | 2001 |
| Oxygen AS | | 2021 |
| P Amundsen Holding AS | | 2022 |
| P. Wangen AS | | 2021 |
| Pab Eiendomsservice AS | Professional & scientific | 2020 |
| Paddy Industrier AS | Wholesale & retail | 2023 |
| Palante Holding AS | | 2024 |
| Pang Event AS | Arts & recreation | 2013 |
| Pantheon AS | Information & communication | 1994 |
| Paperless AS | Information & communication | 1997 |
| Parade Holding AS | Real estate | 2012 |
| Paradise Pizza AS | Hospitality | 2012 |
| Patela AS | Construction | 2019 |
| Patela Drift AS | Construction | 2022 |
| Patrice Dental AS | Health & social care | 2024 |
| Pawinvest AS | | 2022 |
| PBB Profesjonelle Løsninger for Bolig Og Bedrifter Gøransson Og Kristiansen Da | Wholesale & retail | 2002 |
| Pc-Utleie.No AS | Administrative & support | 2011 |
| Pe Mur Og Flis AS | Construction | 2026 |
| Peak Consulting AS | Professional & scientific | 2017 |
| Peico Holding AS | Real estate | 2010 |
| Pennybell Holding AS | | 2026 |
| Perah AS | Professional & scientific | 2018 |
| Pernilletoppen Eiendomsutvikling AS | Real estate | 2023 |
| Pes Jessheim AS | Arts & recreation | 1998 |
| Phatos AS | Professional & scientific | 2026 |
| Phung Saranails AS | Other services | 2024 |
| Pi & T AS | Education | 2014 |
| Pierre Holding AS | Real estate | 2018 |
| Pimm Holding AS | Wholesale & retail | 2025 |
| Pipler AS | Professional & scientific | 2023 |
| Plant Foods AS | Manufacturing | 2023 |
| Plast Assistanse AS | Administrative & support | 2018 |
| Platesjappa Jessheim AS | Wholesale & retail | 2019 |
| Plåt Och Ventilasjonsmontasje AS | Construction | 2004 |
| PM Consult AS | Professional & scientific | 2023 |
| Pop-Up Taxi AS | Transport & logistics | 2026 |
| Popcornhuset AS | Wholesale & retail | 2015 |
| Possiedo AS | Information & communication | 2020 |
| Poulsen Eiendom Holding AS | Real estate | 2012 |
| Poulsen Eiendom Næring AS | Real estate | 2012 |
| Prego Norge AS | Professional & scientific | 1971 |
| Prestby Invest AS | | 2021 |
| Prestige Auto AS | Transport & logistics | 2025 |
| Pretor Bygg AS | Construction | 2015 |
| Prikken Rens AS | Other services | 1988 |
| Pro VVS Oslo AS | Transport & logistics | 2019 |
| Profil Golf AS | Administrative & support | 2020 |
| Propex Gruppen AS | | 2025 |
| Propex Næringsmegling AS | Real estate | 2025 |
| Prosjekt Og Byggeledelse AS | Professional & scientific | 2011 |
| PSV Elektro AS | Construction | 2018 |
| Psychotrauma Therapy & Counselling AS | Health & social care | 2021 |
| Psykiater Britt Børven AS | Health & social care | 2016 |
| Pulla Invest AS | Real estate | 2012 |
| Punkt Reklame AS | Manufacturing | 2005 |
| Pål Gilberg Holding AS | Real estate | 2014 |
| Quality Airport Hotel Gardermoen AS | Hospitality | 1994 |
| Quarion AS | Information & communication | 2025 |
| Quest AS | Real estate | 2011 |
| R.Høghjelm AS | Real estate | 2022 |
| R3ND AS | Professional & scientific | 2018 |
| Ra Bolig AS | Real estate | 2012 |
| Raadmannen AS | Professional & scientific | 2017 |
| Radhakrishnan Holding AS | | 2020 |
| Radonrådgivning AS | Professional & scientific | 2020 |
| Raf Group AS | Wholesale & retail | 2025 |
| Rakne Eiendom AS | Real estate | 2006 |
| Rakvåg Transport AS | Transport & logistics | 2025 |
| Rambekkmoen Gjøvik AS | Real estate | 2015 |
| RB Bolig AS | Real estate | 2020 |
| RB Rør Og Bygg AS | Construction | 2025 |
| Refur AS | Administrative & support | 2026 |
| Regnskapstjenester Romerike AS | Professional & scientific | 2025 |
| Reiret AS | Hospitality | 2025 |
| Rendement AS | Professional & scientific | 2026 |
| Renovera AS | Construction | 2026 |
| Rental AS | Administrative & support | 2019 |
| Rescom AS | Information & communication | 2021 |
| Respect Design AS | Professional & scientific | 2025 |
| Respect Holding- AS | Professional & scientific | 2024 |
| Ribland Invest AS | | 2019 |
| Ricole Consulting Da | Wholesale & retail | 2000 |
| Rigel Holding AS | Financial services | 2016 |
| Ringebu Park AS | Real estate | 2019 |
| Ringen Apotek Holding AS | Wholesale & retail | 2013 |
| Ringen Bandagist AS | Wholesale & retail | 2010 |
| Ringsakerfjellet AS | Real estate | 2017 |
| Ringvegen 31 B Utvikling AS | Real estate | 2016 |
| Ringvoll Boligutvikling AS | Real estate | 2020 |
| Ringvoll Boligutvikling II AS | Real estate | 2021 |
| Ringvoll Holding AS | Real estate | 2024 |
| Risans Holding AS | Administrative & support | 2022 |
| Robe Rent AS | Administrative & support | 2020 |
| Rognstad Byggteknikk AS | Construction | 2014 |