| Merkur Engros AS | Wholesale & retail | 2000 |
| Mester Design AS | Wholesale & retail | 2002 |
| Mesteralliansen AS | Construction | 2015 |
| Metacog AS | Information & communication | 2024 |
| Metas Helse Og NLP Coach AS | Other services | 2012 |
| Meto Gruppen AS | Manufacturing | 2005 |
| Meyers Vaskeservice AS | Administrative & support | 2020 |
| Mica Holding AS | | 2020 |
| Midtgård Holding AS | | 2025 |
| Mifra AS | Wholesale & retail | 2015 |
| Miljø- Gulv AS | Construction | 2023 |
| Mille Moi AS | Wholesale & retail | 2013 |
| Mille Moi Da | Real estate | 2006 |
| Millennium Management AS | Financial services | 2017 |
| Mimir Saga AS | Professional & scientific | 2026 |
| Min Holding AS | Real estate | 2005 |
| Mina Marie Ek AS | Health & social care | 2023 |
| Mindfull Legespesialist AS | Health & social care | 2020 |
| Minutt AS | Real estate | 2021 |
| Mir Og Bek Da | Construction | 2021 |
| Mistral AS | Real estate | 2005 |
| ML Bygg Claes Martin Lindén | Professional & scientific | 2013 |
| Mobile Fredrikstad AS | Other services | 1980 |
| Mobino AS | Information & communication | 2025 |
| Mogensen Fysioterapi AS | Health & social care | 2023 |
| Momsen AS | Professional & scientific | 2021 |
| Moncrieff Consulting AS | Information & communication | 2015 |
| Monsen Maskin AS | Wholesale & retail | 2010 |
| Moonlight Sound AS | Administrative & support | 2015 |
| Moro-Jo AS | Real estate | 2003 |
| Morris Marine Service AS | Transport & logistics | 2021 |
| Morten Strand Holding AS | Construction | 2008 |
| Moss Autoverksted AS | Other services | 2019 |
| Mosseveien 1 AS | Real estate | 2007 |
| Mosseveien 49 Eiendom AS | Real estate | 2023 |
| Mosseveien 5A AS | Real estate | 2004 |
| Motor Forum AS | Other services | 1997 |
| Motorkompaniet Fredrikstad AS | Wholesale & retail | 2020 |
| Moum Leca Eiendom AS | Real estate | 2018 |
| Movana Da | Wholesale & retail | 2010 |
| Moving Pixels AS | Information & communication | 2026 |
| Mre Kapital AS | | 2023 |
| Msement AS | Wholesale & retail | 2024 |
| MSK Klinikken AS | Health & social care | 2011 |
| Mt-Holding AS | | 2026 |
| Mtbyggservice Øst AS | Construction | 2026 |
| Mulac Holding AS | | 2020 |
| Mulligan Indoor Golf AS | Arts & recreation | 2022 |
| Multi AS | Real estate | 1993 |
| Multi Co. Team AS | Water & waste | 2022 |
| Multi Food AS | Wholesale & retail | 1991 |
| Multilogistikk AS | Transport & logistics | 2024 |
| Mumre Holding AS | Professional & scientific | 2023 |
| Munch.Biz Norway AS | Real estate | 2013 |
| Munkene II AS | | 2026 |
| Murkompaniet Eiendom AS | Real estate | 2019 |
| Murkompaniet Invest AS | Construction | 2014 |
| Murkompaniet Østfold AS | Construction | 2019 |
| Myrastien AS | Real estate | 2019 |
| Myrastien Eiendom AS | Real estate | 2020 |
| Mølla Fysioterapi Da | Health & social care | 2010 |
| MØLLA SERVERING Terje Severinsen Morten Markussen DA | Hospitality | 1991 |
| Møller & Anwar Holding AS | | 2025 |
| Møllerstuen AS | Real estate | 1997 |
| Nails 4U AS | Other services | 2021 |
| Naked Green AS | Manufacturing | 2026 |
| Namco Prosjekt AS | | 1999 |
| Naprapathuset Consult AS | Health & social care | 2021 |
| Naprapathuset Da | Health & social care | 2007 |
| Nas Eiendom AS | Real estate | 2023 |
| Nas Holding AS | Construction | 2018 |
| Navesta AS | Real estate | 2014 |
| NB & Partnere AS Avd Borg | Financial services | 1997 |
| Neatlaidigs AS | Real estate | 2025 |
| Nedre Glommen Bygg AS | Construction | 1998 |
| Nedre Glommen Legegruppe Da | Health & social care | 2003 |
| Nellys Kebab House AS | Hospitality | 2007 |
| Nera Invest AS | Professional & scientific | 1990 |
| Nesveien 63 AS | Real estate | 1983 |
| Net Retail Group AS | Wholesale & retail | 2020 |
| Netrom Fredrikstad AS | Professional & scientific | 2008 |
| Netron AS | Professional & scientific | 2002 |
| Nettkursene Ans | Information & communication | 2000 |
| New You Barber Shop AS | Other services | 2024 |
| Nexgen MST AS | | 2024 |
| Nexgen MST Technologies AS | Information & communication | 2024 |
| Next Step Accounting AS | Professional & scientific | 2025 |
| NFV AS | Professional & scientific | 2018 |
| NFV Holding AS | | 2022 |
| Ni-Ri AS | Wholesale & retail | 2016 |
| Nicolaysen Holding AS | Financial services | 2011 |
| Nikini Investments AS | Financial services | 2013 |
| Niko Holding AS | | 2026 |
| Niko Sales Partner AS | Administrative & support | 2026 |
| Nilsen & Sandvik AS | Construction | 2020 |
| Nilsen LLB AS | Arts & recreation | 2024 |
| Nina Ryen Holding AS | Real estate | 2008 |
| Nini Beach AS | Hospitality | 2015 |
| Noahs Engler Da | Hospitality | 2001 |
| Noas Park Barnehage AS | Education | 2018 |