| Marine Bio Solutions AS | Agriculture & fishing | 2015 |
| Marine Cluster AS | Professional & scientific | 2020 |
| Marine Enterprise Solutions AS | Administrative & support | 2021 |
| Marinet AS | Information & communication | 2018 |
| Marinevold Invest AS | Financial services | 2011 |
| Mario Nordly Holding AS | Wholesale & retail | 2024 |
| Marisco Eiendom AS | Real estate | 2019 |
| Marisco Holding AS | Real estate | 2019 |
| Marita Mo Risøy Kiropraktikk, Helse Og Bevegelse AS | Health & social care | 2017 |
| Mariteam AS | Administrative & support | 2000 |
| Maritime Management AS | Transport & logistics | 1993 |
| Maritime Robotics AS | Professional & scientific | 2005 |
| Marits AS | Real estate | 1995 |
| Marius Bolig AS | Real estate | 2022 |
| Marius Eiendom Nye AS | Real estate | 2017 |
| Marius Maske AS | Financial services | 2011 |
| Marius-Holding AS | Real estate | 2016 |
| Marjo Invest AS | | 2025 |
| Marka Eiendom AS | Real estate | 2013 |
| Markadi AS | Information & communication | 2022 |
| Markedsføring Norge AS | Professional & scientific | 2013 |
| Markedsservice Midt Norge AS | Professional & scientific | 1996 |
| Marken Ventures AS | | 2026 |
| Markens Veg 5 AS | Real estate | 2019 |
| Markhusan AS | Real estate | 2009 |
| Markisedesign AS | Wholesale & retail | 2020 |
| Markus Dahl-Hanssen AS | Information & communication | 2023 |
| Markus Lantto | Arts & recreation | 2013 |
| Markus Roland Holding AS | | 2026 |
| Marmelli Holding AS | | 2025 |
| Marmet Holding AS | Wholesale & retail | 2017 |
| Maroad AS | Information & communication | 2020 |
| Marokko Holding AS | | 2023 |
| Marra Invest AS | | 2020 |
| Marsha AS | Real estate | 2024 |
| Marson AS | | 2023 |
| Marte Hasselø Holding AS | | 2023 |
| Marthe Holding AS | | 2024 |
| Martin Mobråten Invest AS | Financial services | 2018 |
| Mary Me Young Da | Arts & recreation | 2006 |
| Mas Invest AS | | 2020 |
| Mas Marl Holding AS | | 2021 |
| Masaj AS | Financial services | 2005 |
| Masan Holding AS | | 2019 |
| Masibo AS | Real estate | 2024 |
| Mask Frisør AS | Other services | 2020 |
| Maske Holding AS | | 2023 |
| Maske Invest AS | | 2021 |
| Maskin & Graveservice AS | Construction | 1991 |
| Maskineriet Trondheim AS | Administrative & support | 2016 |
| Maskinutleie Trøndelag AS | Administrative & support | 2020 |
| Masol AS | Real estate | 2011 |
| Masoma Invest AS | Real estate | 2017 |
| Massawa Butikk AS | Wholesale & retail | 2018 |
| Massetransport AS | Transport & logistics | 2001 |
| Massilian AS | Professional & scientific | 2021 |
| Massimo Invest AS | Financial services | 2015 |
| Mastemyr Hotell AS | Real estate | 2006 |
| Master Solutions AS | Professional & scientific | 2020 |
| Masumi Holdning AS | Real estate | 2026 |
| Mat Er Livretten Min AS | Wholesale & retail | 2021 |
| Mat Fra Midtøsten AS | Hospitality | 2020 |
| Mat Og Innovasjon AS | Hospitality | 2009 |
| Matatag Invest AS | Real estate | 2011 |
| Matel Invest AS | Information & communication | 2023 |
| Material AS | | 2021 |
| Materio AS | Real estate | 2009 |
| Mathall Trondheim AS | Real estate | 2015 |
| Matheson Bones Holding AS | | 2026 |
| Mathesongården Legesenter AS | Health & social care | 2024 |
| Mathias Aarseth Pedersen AS | | 2024 |
| Matho AS | Financial services | 2009 |
| Matho Invest AS | Financial services | 2005 |
| Matigruppen AS | Hospitality | 2023 |
| Matilda Foodtech Norge AS | Information & communication | 1996 |
| Matina AS | | 2021 |
| Matiq AS | Information & communication | 2002 |
| Matkollektivet SA | Other services | 2016 |
| Matrix Data Sjøflot & Lillestøl Ans | | 1987 |
| Mats Eng Service - Ventilasjon | Construction | 2004 |
| Mats Finsås Holding AS | | 2024 |
| Mats I Koch Holding AS | | 2023 |
| Mats Nilsen Holding AS | Financial services | 2005 |
| Matti Holding AS | | 2023 |
| Mattsons Aksjeselskap | Administrative & support | 2022 |
| Maua Holding AS | | 2019 |
| Maudal Invest AS | | 2024 |
| Mauri AS | | 2022 |
| Mavi XV AS | Financial services | 2007 |
| Mavi Xxix AS | | 2021 |
| Mawas Holding AS | | 2025 |
| Mawi Invest AS | | 2020 |
| Max Puls Fitness AS | Arts & recreation | 2008 |
| Maxilla AS | Health & social care | 2001 |
| Maximillianus AS | | 2024 |
| Maxwell Norge AS | Professional & scientific | 2014 |
| Mayoko Invest AS | | 2026 |
| Mazemap AS | Information & communication | 2013 |
| MB Blikk AS | Real estate | 2013 |
| MB Tech Holdco AS | | 2026 |