| M-Distribusjon AS | Wholesale & retail | 2010 |
| M.Bolstad Holding AS | | 2025 |
| Magne Kviserud AS | Real estate | 1986 |
| Makan Te Mat AS | Hospitality | 2015 |
| Makan Te Mat Da | Hospitality | 2010 |
| Malern Farge Og Interiør AS | Wholesale & retail | 2020 |
| Mandt Bygg AS | Construction | 2019 |
| Marit Og Lises Stoff Ans | Wholesale & retail | 1992 |
| Marker Og Eidsberg Sparebank | Financial services | 1848 |
| Maskin Og Utemiljø AS | Administrative & support | 2005 |
| Maso Invest AS | Real estate | 2023 |
| Mauritz Eiendom AS | Other services | 2005 |
| Mauritz Holding AS | Other services | 2005 |
| Maurtvedt Boligutleie AS | Real estate | 2014 |
| Maurtvedt Eiendom AS | Real estate | 2022 |
| Maxi Grillen Da | Hospitality | 1992 |
| Maximuz Persontransport AS | Transport & logistics | 2025 |
| MB Renhold AS | Administrative & support | 2022 |
| Medgar Utleie AS | Real estate | 2026 |
| Meles Utvikling AS | | 2025 |
| Melleby Og Berg AS | Other services | 2020 |
| Melodent Mysen AS | Health & social care | 2005 |
| Meraki by Evensen AS | Professional & scientific | 2026 |
| Meyco AS | Professional & scientific | 2021 |
| MG Eiendom AS | Real estate | 2014 |
| Mickes Varetransport AS | Transport & logistics | 2024 |
| Miljølandskap Anlegg AS | Administrative & support | 2003 |
| Miljølandskap Sørby AS | Administrative & support | 2006 |
| Mim Gården AS | Real estate | 2002 |
| Mitt Univers AS | Professional & scientific | 2023 |
| Mmy Holding AS | | 2021 |
| Momarken Hestesportbutikk AS | Wholesale & retail | 2023 |
| Momarken Toto AS | Arts & recreation | 1997 |
| Momarken Varmepumpeservice AS | Construction | 2020 |
| Mona Betong AS | Manufacturing | 2005 |
| Mona Mek AS | Manufacturing | 1982 |
| Mona Mek Eiendom AS | Real estate | 2023 |
| Morgan F. AS | Construction | 2006 |
| Morten Authen AS | Wholesale & retail | 2011 |
| Mozart Ellen Marie Ødegård Og Gitte Grav Da | Wholesale & retail | 2004 |
| MR. Pukk Øst AS | Mining & quarrying | 1962 |
| Mtø AS | Transport & logistics | 2024 |
| Mustorp Grustak Da | Mining & quarrying | 2002 |
| Mysebu Arrangement AS | Hospitality | 1998 |
| Mysen Asfalt AS | Manufacturing | 2023 |
| Mysen Bilverksted AS | Other services | 2010 |
| Mysen Bruktmusikk Da | Wholesale & retail | 2023 |
| Mysen Burger AS | Hospitality | 2018 |
| Mysen Bygg AS | Construction | 2023 |
| Mysen Campino Pizza Kebab AS | Hospitality | 2025 |
| Mysen Campino Pizzeria Da | Hospitality | 2012 |
| Mysen Cementstøperi AS | Manufacturing | 1991 |
| Mysen Dyreklinikk AS | Professional & scientific | 2012 |
| Mysen Eiendom AS | Real estate | 2014 |
| Mysen Eiendomsutvikling AS | Real estate | 2019 |
| Mysen Eiendomsutvikling Holding AS | Real estate | 2020 |
| Mysen Gamle Snekkerverksted AS | Real estate | 1992 |
| Mysen Glass Og Leker AS | Wholesale & retail | 2010 |
| Mysen Isolasjonsservice AS | Construction | 2015 |
| Mysen Kontoret AS | Health & social care | 2020 |
| Mysen Kornsilo Og Mølle SA | Manufacturing | 1951 |
| Mysen Legesenter AS | Health & social care | 2024 |
| Mysen Maskin AS | Administrative & support | 2011 |
| Mysen Maskinutleie Ans | Administrative & support | 2003 |
| Mysen Motorcenter AS | Other services | 2019 |
| Mysen Pizza & Kebab AS | Hospitality | 2019 |
| Mysen Prestasjon Og Helse AS | Education | 2019 |
| Mysen Skomagasin AS | Wholesale & retail | 2014 |
| Mysen Sport AS | Wholesale & retail | 2000 |
| Mysen Sushi Og Mer AS | Hospitality | 2023 |
| Mysen Takservice AS | Construction | 1988 |
| Mysen Tannteknikk AS | Manufacturing | 1992 |
| Mysen Transportservice AS | Transport & logistics | 2012 |
| Mysenregionen AS | Other services | 1998 |
| Myzen Holding AS | Health & social care | 2022 |
| Møbelringen Mysen AS | Wholesale & retail | 1991 |
| Møbelsnekkerskolen AS | Education | 2012 |
| N-H Eiendom AS | Real estate | 2021 |
| Neb Bygg Og Rehab AS | Construction | 2018 |
| Netconnect Norge AS | Construction | 2013 |
| Never Stop AS | | 2024 |
| Nivu AS | Hospitality | 2018 |
| Nivu Eiendom AS | Real estate | 2022 |
| Nor-Mak Bygg AS | Construction | 2017 |
| Norbag Norge AS | Wholesale & retail | 2008 |
| Nord Tek Maskin AS | Wholesale & retail | 2025 |
| Norddisk AS | Construction | 2018 |
| Nordisk Service Installation AB | Construction | 2010 |
| Nordisk Tungbilservice AS | Other services | 2025 |
| Nore SA | Real estate | 2006 |
| Norgesjord AS | Manufacturing | 2022 |
| Norsk Travtipstjeneste AS | Arts & recreation | 1996 |
| Norvigroup Norsk Dun AS | Manufacturing | 2002 |
| Norvigroup Sweden AB | Wholesale & retail | 2004 |
| Norweka AS | Information & communication | 2024 |
| Norweka Group AS | Information & communication | 2023 |
| Nsa Legacy AS | Education | 2026 |
| Ocke Invest AS | Transport & logistics | 2023 |
| Odal Transport AS | Transport & logistics | 2022 |
| Olafsrud & Co Møbelsenter Ans | Wholesale & retail | 1912 |