| Mottaket Media AS | Information & communication | 2021 |
| Mov Huser Holding AS | Real estate | 2021 |
| MR Lee B AS | Arts & recreation | 2025 |
| MSH Holding AS | Real estate | 2008 |
| MSK Drift Lillestrøm AS | Health & social care | 2022 |
| MSK Helse AS | Health & social care | 2022 |
| MSK Spesialistsenteret AS | Health & social care | 2021 |
| Mundiada Agency AS | Information & communication | 2023 |
| Mundiada Holding AS | Information & communication | 2023 |
| Murer På Hjul AS | Wholesale & retail | 2024 |
| Murphy Regnskap AS | Professional & scientific | 2006 |
| Myeducation - Norge AS | Education | 2012 |
| Myers Invest AS | | 2020 |
| Myhre Sandum Invest AS | | 2023 |
| Myhrers RTB AS | Professional & scientific | 1967 |
| Myntegaard AS | Professional & scientific | 2025 |
| Myrvoll Torg AS | Real estate | 2016 |
| Møbelringen O. Syversen Lillestrøm AS | Wholesale & retail | 1987 |
| Møller Holding AS | Professional & scientific | 2018 |
| Møllhausen Konditorier AS | Real estate | 1935 |
| Naborly AS | Information & communication | 2025 |
| Nad AS | Health & social care | 2024 |
| Nad Medical AS | Health & social care | 2026 |
| Nails & Spa Lillestrøm AS | Other services | 2015 |
| Nakamoto Holding AS | Real estate | 2016 |
| Namar AS | Professional & scientific | 2019 |
| Nameless Holding AS | Real estate | 2013 |
| Nanosoft AS | Information & communication | 2022 |
| Naomi Invest AS | | 2022 |
| Napop AS | Professional & scientific | 2021 |
| Napp No Da | Wholesale & retail | 2001 |
| Narum Handelskompani AS | | 2022 |
| Natalias Hud Og Fot AS | Other services | 2021 |
| Natur Balans AS | Manufacturing | 2026 |
| Nedre Enger AS | Real estate | 2006 |
| Nedre Romerike AS | Real estate | 2012 |
| Nedre Rælingsvei 138 AS | Real estate | 2010 |
| Nelson Garden Holding AS | Manufacturing | 2017 |
| Nemesis Eiendom AS | Real estate | 2013 |
| Nemeth Finans AS | Manufacturing | 2005 |
| Nemus Lillestrøm Fysioterapi AS | Health & social care | 2006 |
| Nero Eiendomsmegling AS | Real estate | 2003 |
| Nesgata 2 AS | Real estate | 2014 |
| Nesgata 20 AS | Real estate | 2019 |
| Nestu AS | Financial services | 2009 |
| Nettify AS | Information & communication | 2026 |
| Neuroclinic.No AS | Health & social care | 2018 |
| New Future Invest AS | Real estate | 2017 |
| Newyou Concrete Design Studio Da | Professional & scientific | 2005 |
| Nexsus Fiber Optics AS | Information & communication | 2017 |
| Next Layer AS | Information & communication | 2025 |
| Next Step Growth Inc Nuf | Professional & scientific | 2015 |
| Next Utdanning AS | Education | 2023 |
| Nextidea AS | | 2021 |
| Nisa Engros AS | Wholesale & retail | 2021 |
| Nitelva Helsesenter AS | Health & social care | 2014 |
| Nitteberg Panorama AS | Real estate | 2011 |
| Nittedalsg 17 AS | Real estate | 1971 |
| Nittedalsgata 12 AS | Professional & scientific | 2007 |
| NL Kirkegt. 6 AS | Health & social care | 2010 |
| Nmore AS | Information & communication | 2017 |
| Nohedas AS | Information & communication | 2025 |
| Nokian Dekk AS | Wholesale & retail | 1947 |
| Noradapt AS | Manufacturing | 2001 |
| Noras Eiendom AS | Real estate | 2018 |
| Norasonde Arbeidsinkludering AS | Health & social care | 2015 |
| Norasonde Eiendom AS | Real estate | 2005 |
| Norasonde Karriere AS | Education | 2015 |
| Norasonde Kommunale Tjenester AS | Administrative & support | 2025 |
| Norasonde Læringssenter AS | Education | 2015 |
| Norasondegruppen AS | Health & social care | 1960 |
| Nordic Automotive AS | Wholesale & retail | 2023 |
| Nordic Bedrift AS | Professional & scientific | 2021 |
| Nordic Implants & Specialists AS | Wholesale & retail | 2018 |
| Nordic Smart Host AS | Professional & scientific | 2025 |
| Nordisk Mobilvask AS | Other services | 2026 |
| Nordlie Holding AS | Financial services | 2017 |
| Nordlys VVS AS | Construction | 2014 |
| Nordmanngården AS | Real estate | 1972 |
| Nordpolen 1 Ans | Real estate | 1988 |
| Nordpolen Invest AS | Professional & scientific | 2000 |
| Nordshade AS | Construction | 2026 |
| Nordsnoveien 2 AS | Real estate | 2025 |
| Nordsnoveien AS | Real estate | 2023 |
| Nordstrand Næringseiendom AS | Real estate | 2014 |
| Nordvang Maskin AS | Wholesale & retail | 1994 |
| Nordvika Ventilasjon AS | Administrative & support | 2025 |
| Norelcon AS | Professional & scientific | 2013 |
| Norges Varemesse Eiendom AS | Real estate | 1993 |
| Norgesft AS | Transport & logistics | 2014 |
| Norgesregulering AS | Health & social care | 2021 |
| Norinett Da | Information & communication | 2004 |
| Norliance AS | Professional & scientific | 2025 |
| Norse Decom AS | Professional & scientific | 2001 |
| Norsk Bedrift Partner AS | Construction | 1996 |
| Norsk Ferdigplen AS | Agriculture & fishing | 2012 |
| Norsk Indeksforvaltning AS | Administrative & support | 2013 |
| Norsk Prosjektutvikling AS | | 2020 |
| Norsk Tivolidrift AS | Arts & recreation | 1998 |
| Norstrøm AS | Hospitality | 1989 |