| Norsk Tekstilgjenvinning AS | Water & waste | 2021 |
| Norsk Tekstilsortering AS | Manufacturing | 2022 |
| Norsk Vvs-Merking AS | Construction | 1996 |
| Norsk Web-Design Ans | Information & communication | 1998 |
| Norstell Stillas AS | Construction | 2011 |
| Northcliff Holding AS | | 2026 |
| Northern Technology Holding AS | | 2005 |
| Northstar Collective AS | Professional & scientific | 2026 |
| Northwall AS | Information & communication | 2021 |
| NORVA24 Vestfold AS | Water & waste | 2005 |
| Norvator AS | Administrative & support | 1991 |
| Norved AS | Manufacturing | 2006 |
| Norway Power Yoga AS | Arts & recreation | 2016 |
| Norwegian Cruise Charter AS | Professional & scientific | 2014 |
| Norwegian Giants AS | Arts & recreation | 2024 |
| Norwegian Partners Ans | | 1992 |
| Norwegian Toy House SA | Administrative & support | 2020 |
| Norwia AS | Manufacturing | 2010 |
| Norx Entreprenør AS | Construction | 2023 |
| Notech AS | Manufacturing | 1990 |
| Notek Holding AS | Real estate | 2000 |
| Notsiamese Ans | | 1994 |
| Novanor Scandinavia AS | Wholesale & retail | 2010 |
| Novi Media AS | Professional & scientific | 2025 |
| Novin AS | Health & social care | 2023 |
| Novo AS | Wholesale & retail | 2025 |
| Novoh AS | Wholesale & retail | 2013 |
| Novumo AS | Wholesale & retail | 2007 |
| Novus Råd Og Regnskap AS | Professional & scientific | 2003 |
| Nox Holding AS | Professional & scientific | 2017 |
| Nra Holding AS | | 2021 |
| NTS Kompetanse AS | Education | 2017 |
| Nuva AS | Information & communication | 2024 |
| Nuvik AS | Construction | 2026 |
| Nybyen AS | Hospitality | 2026 |
| Nye Arne Rød & Co AS | Construction | 2023 |
| Nye Bbeh AS | | 2025 |
| Nye BBH AS | | 2025 |
| Nye Beck Holding AS | Manufacturing | 2020 |
| Nye Dråper AS | Hospitality | 2020 |
| Nye Hegnasletta 10 AS | Real estate | 2023 |
| Nye Lufthavn Holding AS | Administrative & support | 2009 |
| Nye Pepfjord AS | Hospitality | 2023 |
| Nye Vaner AS | Professional & scientific | 2007 |
| Nygårdsveien 53 AS | Real estate | 2019 |
| Nygårdsveien 68 AS | Real estate | 1966 |
| Nygårdsveien 76 AS | Real estate | 2012 |
| Nygårdsveien 79 AS | Real estate | 2016 |
| Nygårdsveien 80 AS | Real estate | 2007 |
| Nygårdsveien 82 AS | Real estate | 2006 |
| Nyléns Elektriske AS | Construction | 2018 |
| Nyra Invest AS | | 2019 |
| Nytbyn AS | Real estate | 2012 |
| Nå Metallretur & Eiendom AS | Water & waste | 2013 |
| Næss Eiendom AS | Real estate | 2023 |
| Nørgaard AS | Wholesale & retail | 2024 |
| O2 Byggteknikk AS | Real estate | 2012 |
| Oag AS | Education | 2017 |
| Oakstream Holding AS | | 2020 |
| Oceana AS | Financial services | 2003 |
| Oceana Navigation AS | Financial services | 2013 |
| Oceanedge AS | Information & communication | 2025 |
| Ocg Invest AS | Real estate | 2020 |
| Octo AS | Professional & scientific | 2006 |
| Oculaudio AS | Information & communication | 2017 |
| Oculaudio Corti AS | Information & communication | 2023 |
| Ocumed AS | Health & social care | 2019 |
| Odd AS | Real estate | 1993 |
| Odd Gleditsch AS | Financial services | 1971 |
| Oddenes Holding AS | Real estate | 2015 |
| Oddenes Invest AS | Financial services | 2014 |
| Oddolsen Holding AS | Financial services | 2017 |
| Odel Utvikling AS | Wholesale & retail | 2001 |
| Oecosystematis Intelligentes AS | Real estate | 2017 |
| Off Grid Invest AS | Professional & scientific | 2023 |
| Offshore Composites AS | Professional & scientific | 1999 |
| Oj Jacobsen AS | | 2024 |
| Ok Bygg AS | Construction | 2021 |
| Okr Consulting AS | Professional & scientific | 2013 |
| Ol Transport AS | Transport & logistics | 2024 |
| Olafsen Transporttjenester AS | Transport & logistics | 2025 |
| Olavia AS | Real estate | 2005 |
| Olavia Eiendom AS | Real estate | 2007 |
| Olavia Invest AS | Real estate | 2005 |
| Olavia Media AS | Information & communication | 2006 |
| Olavssagaen.No Ans | Information & communication | 2004 |
| Olberg & Løberg Da | Professional & scientific | 2010 |
| Ole Olsen AS | Wholesale & retail | 2010 |
| Ole Ramsdal AS | Professional & scientific | 2023 |
| Olegull Holding AS | | 2024 |
| Olei Holding AS | Financial services | 2018 |
| Oleon NV | Manufacturing | 2002 |
| Ollebakken 17 AS | Real estate | 2020 |
| Ollebakken Holding AS | Professional & scientific | 2021 |
| Olstad Hansen Eiendom AS | Real estate | 2005 |
| Omega Nutrition AS | Health & social care | 2012 |
| Oml Invest AS | Real estate | 2008 |
| Online Regnskap AS | Professional & scientific | 2015 |
| ONLINE4U AS | Information & communication | 2002 |
| Opio Invest AS | Information & communication | 2005 |