| M12 Tromsø AS | Hospitality | 2018 |
| Maadavaar Holding AS | Real estate | 2005 |
| Mach Holding AS | | 2020 |
| Mack Ad AS | Professional & scientific | 2021 |
| Mack AS | Hospitality | 2016 |
| Mack Bar AS | Hospitality | 2015 |
| Mack Concepts AS | Professional & scientific | 2020 |
| Mack DC AS | Professional & scientific | 2021 |
| Mack Ec AS | Administrative & support | 2021 |
| Mack Eiendommene AS | Real estate | 2017 |
| Mack En AS | Professional & scientific | 2020 |
| Mack to AS | Professional & scientific | 2020 |
| Mack Øst AS | Real estate | 2014 |
| Macko AS | Real estate | 2005 |
| Macks Ølbryggeri AS | Manufacturing | 1995 |
| Mae Investments AS | | 2023 |
| Magiskeminner AS | Professional & scientific | 2024 |
| Magma Fashion AS | Wholesale & retail | 2020 |
| Magnar Nordvik San Rafael 58 Da | Real estate | 1993 |
| Magnetic North Expeditions AS | Administrative & support | 2026 |
| Mahen Holding AS | | 2025 |
| Maks Regnskap AS | Professional & scientific | 2022 |
| Malabarisk Da | Arts & recreation | 2025 |
| Malangen Utvikling AS | Real estate | 2004 |
| Maleran AS | Construction | 1995 |
| Malersentralen Tromsø AS | Construction | 2022 |
| Maling Og Flis AS | Construction | 2016 |
| Malmo Properties AS | Real estate | 2021 |
| Malmporten Handelspark AS | Real estate | 2008 |
| Mamara AS | | 2023 |
| Mamu Holding AS | Financial services | 2015 |
| Manfjord AS | Real estate | 1986 |
| Manu & Salutem AS | Other services | 2020 |
| Map.D Nord Norge AS | Information & communication | 2024 |
| Mar Utleie AS | Real estate | 2020 |
| Marealis AS | Professional & scientific | 1996 |
| Marenos Holding AS | | 2022 |
| Margot Holding AS | | 2024 |
| Maric Invest AS | | 2024 |
| Marin Nord Holding AS | | 2026 |
| Marine Gem AS | Manufacturing | 2015 |
| Marine Spark X AS | Professional & scientific | 2024 |
| Marine Supply AS | Wholesale & retail | 1997 |
| Marinewide AS | Professional & scientific | 2019 |
| Marinvest AS | Wholesale & retail | 1998 |
| Maritim Center AS | Wholesale & retail | 1974 |
| Maritim Center Eiendom AS | Wholesale & retail | 2011 |
| Maritim Elektroservice AS | Construction | 2021 |
| Maritim Holding AS | Real estate | 2022 |
| Maritim Sveiseservice AS | Manufacturing | 2016 |
| Maritim Sveiseservice Eiendom AS | Manufacturing | 2016 |
| Maritim Sveiseservice Holding AS | Manufacturing | 2016 |
| Maritime Competence AS | Transport & logistics | 1992 |
| Maritime Solution Limited Nuf | Information & communication | 2007 |
| Marits Fotterapi AS | Health & social care | 2015 |
| Markedshuset AS | Wholesale & retail | 1999 |
| Markedshuset Eiendom AS | Real estate | 1999 |
| Markedshuset Invest AS | Wholesale & retail | 2013 |
| Marlu AS | Real estate | 2018 |
| Marsi AS | Real estate | 2006 |
| Marstrander AS | | 2025 |
| Marte Fønnebø Fysioterapi AS | Health & social care | 2023 |
| Maskin & Eiendom AS | Construction | 2013 |
| Maskin- Og Snøservice AS | Construction | 2023 |
| Maskinentreprenør Fundamentering Og Graving AS | Construction | 2026 |
| Maskinentreprenør Herbjørn Nilssen AS | Construction | 1998 |
| Maskinentreprenør Jarle Johansen AS | Construction | 2020 |
| Maskinentreprenør Stig Kristiansen AS | Construction | 1987 |
| Maskinsvingen 3 AS | Real estate | 2010 |
| Maskinverkstedet AS | Hospitality | 2019 |
| Masoni AS | Professional & scientific | 2023 |
| Mathallen Tromsø AS | Wholesale & retail | 1989 |
| Mathias Gabrielsen AS | Real estate | 2016 |
| Mathiassen AS | | 2021 |
| Matrøyk AS | Wholesale & retail | 2003 |
| Mats Bergvoll AS | Wholesale & retail | 2021 |
| Matt Eiendom AS | Real estate | 2021 |
| Maxibygg AS | Real estate | 2016 |
| Maximus Assets AS | | 2020 |
| Maxinvest AS | Real estate | 2009 |
| MBH Holding AS | Information & communication | 2018 |
| Mdco Tromsø AS | Health & social care | 1994 |
| Mdons Invest AS | | 2024 |
| Media Event AS | Information & communication | 2017 |
| Mediaskjerm AS | Information & communication | 2014 |
| Mediehuset Itromsø AS | Information & communication | 1971 |
| Mediva AS | Health & social care | 2014 |
| Medsensio AS | Information & communication | 2017 |
| Mei Community AS | Administrative & support | 2025 |
| Meierigaarden AS | Real estate | 2017 |
| Meieriprosjektet AS | Real estate | 2024 |
| Meiland Invest AS | | 2025 |
| Mekta AS | | 1986 |
| Mel Tromsø 14 AS | Real estate | 2023 |
| Mel Tromsø 15 AS | Real estate | 2023 |
| Mel Tromsø 5 AS | Real estate | 2023 |
| Mel Tromsø 8 AS | Real estate | 2023 |
| Mellom Arts Da | Arts & recreation | 2021 |
| Mellomveien 23 Eiendom AS | Real estate | 1966 |
| Mellows AS | Real estate | 2020 |