| MSB Holding AS | Professional & scientific | 2008 |
| MTN Transport AS | Transport & logistics | 2012 |
| Multi Parts AS | Other services | 1995 |
| Myhre Frisør AS | Other services | 1999 |
| Myking Utvikling AS | Construction | 2016 |
| Mælumenga Terrasse AS | Real estate | 2015 |
| Møbelsnekkerne AS | Manufacturing | 2025 |
| NCG Holding AS | Real estate | 2019 |
| Ncgs AS | Construction | 2012 |
| Nedre Brennaveien Kværner Veilag SA | Real estate | 1954 |
| Nedre Knive Skog Da | Agriculture & fishing | 1995 |
| Negotiation AS | Education | 1998 |
| Nelara AS | Real estate | 2008 |
| Nendus Holding AS | Wholesale & retail | 2018 |
| Nibe Holding AS | Construction | 2015 |
| Nick Auto AS | Wholesale & retail | 2022 |
| Nikkerud Transport Og Kranservice AS | Transport & logistics | 1997 |
| Nils Ivar Braathen AS | Transport & logistics | 2012 |
| Ninni AS | Financial services | 2009 |
| Nittenen AS | | 2024 |
| Nka Holding AS | | 2024 |
| Nobb Eiendom AS | Real estate | 2008 |
| Norarchedium AS | Professional & scientific | 2023 |
| Noratel AS | Manufacturing | 2004 |
| Norcomo AS | | 2026 |
| Norden Media AS | Professional & scientific | 2025 |
| Nordic Auto AS | Wholesale & retail | 2024 |
| Nordisk Kvalitet AS | Construction | 2023 |
| Nordlis Industriservice AS | Manufacturing | 1997 |
| NORDOG Ans Leif Børre og Marianne Andersen | | 1988 |
| Noresund Utvikling AS | Real estate | 2021 |
| Norgesplanter AS | Agriculture & fishing | 2005 |
| Norsk Boligutleie AS | Real estate | 2021 |
| Norsk Dekkvulkanisering AS | Other services | 2007 |
| Norsk Sveiseteknikk AS | Wholesale & retail | 1991 |
| Nova of Norway AS | Wholesale & retail | 2000 |
| NRG Group AS | Wholesale & retail | 2025 |
| NTG AS | Construction | 1992 |
| NVH AS | Professional & scientific | 2024 |
| Nybråten Transport AS | Transport & logistics | 2016 |
| Nærbøe Holding AS | Real estate | 2021 |
| Næss Salg Og Industriservice AS | Wholesale & retail | 2011 |
| Nøstetangen Cafe AS | Hospitality | 2022 |
| Nøstetangen Entreprenør AS | Construction | 2012 |
| Nøstetangen Fysikalske Institutt AS | Health & social care | 2013 |
| O K Lie AS | Construction | 2000 |
| O L Senteret AS | Other services | 1987 |
| O.T.B Eiendom AS | Real estate | 2007 |
| O.T.B Holding AS | Real estate | 2007 |
| O.T.B Service AS | Manufacturing | 2007 |
| Ok Lie Maskin AS | Administrative & support | 2005 |
| Ole Holth Invest AS | Financial services | 2015 |
| One to One AS | Professional & scientific | 2015 |
| One to One Holding AS | Professional & scientific | 2004 |
| Onetank AS | Manufacturing | 2018 |
| Opsahl Dekk AS | Wholesale & retail | 2026 |
| Opsahlhaven AS | Real estate | 2015 |
| Opsahlhaven Utvikling AS | Real estate | 2019 |
| Optimal Form AS | Wholesale & retail | 2025 |
| ORION VERTSHUS ANS Sanden og Hagen | Hospitality | 1990 |
| Orker Ikke Production Da | Information & communication | 2020 |
| Orkidehøgda Eiendom AS | Real estate | 2014 |
| Ormåsen Utbygging AS | Real estate | 2016 |
| Oso Energy AS | Wholesale & retail | 2020 |
| Oso Group AS | Wholesale & retail | 1984 |
| Oso Hotwater AS | Manufacturing | 2003 |
| Oso Logistics AS | Real estate | 2023 |
| Oso Property AS | Real estate | 1992 |
| Oso Technology AS | Administrative & support | 2005 |
| Otterstrom Racing AS | Education | 2023 |
| Ovenstad AS | Information & communication | 2024 |
| Padel Friends AS | | 2021 |
| Pafo Holding AS | | 2026 |
| Pahar AS | Wholesale & retail | 2025 |
| Pai Holding AS | | 2020 |
| Paintball Gear AS | Wholesale & retail | 2013 |
| Palmyra Frisør AS | Other services | 2025 |
| Panorama Inøst AS | | 2017 |
| Papson AS | Construction | 2021 |
| Paradiso Pizza & Grill Hokksund AS | Hospitality | 2024 |
| Partum Holding AS | Real estate | 2013 |
| Partum Utvikling AS | Construction | 2015 |
| Partum Utviklingselskap I AS | Real estate | 2021 |
| Pax Kundalini Yoga AS | Education | 2015 |
| PCB Sanering AS | Professional & scientific | 1998 |
| PCV Holding AS | Construction | 2023 |
| Pef Invest AS | Real estate | 2007 |
| Pek 551 Holding AS | | 2023 |
| Pell AS | Wholesale & retail | 2021 |
| Per Egil Berg Holding AS | | 2026 |
| PHM Holding AS | Real estate | 2020 |
| Pippei AS | Wholesale & retail | 2025 |
| Pizzabringeren AS | Hospitality | 2016 |
| Pizzeria Italia Ans | Hospitality | 2003 |
| Plan- Og Byggsikring AS | Professional & scientific | 2016 |
| Plantespesialisten AS | Wholesale & retail | 2020 |
| Polarnor AS | Wholesale & retail | 2025 |
| Power Elektro AS | Construction | 2019 |
| Poweron AS | Manufacturing | 2015 |
| PP Eiendomsinvest AS | Real estate | 2018 |