| Marina AS | Wholesale & retail | 1980 |
| Marine Norway AS | Professional & scientific | 2011 |
| Marine Og Industrireparasjoner AS | Manufacturing | 2025 |
| Marine Og Industrireparasjoner AS | Manufacturing | 2009 |
| Marine Rep Eiendom AS | Real estate | 2025 |
| Marine Rep Holding AS | | 2025 |
| Maritim Badstuer Haugesund AS | Other services | 2023 |
| Maritime Audit AS | Professional & scientific | 2006 |
| Markedet AS | Real estate | 2013 |
| Markedet Drift AS | Real estate | 2013 |
| Markedet Legesenter Administrasjon AS | Health & social care | 2014 |
| Markeds Invest AS | Administrative & support | 1974 |
| Mary-Ann Hårdesign AS | Other services | 2012 |
| Matgleder Pluss AS | Real estate | 2002 |
| Math Lande Møbler AS | Wholesale & retail | 1997 |
| Matpakken Da | Hospitality | 2007 |
| Matre-Tangen AS | Arts & recreation | 2024 |
| Matvareexpressen AS | Wholesale & retail | 2008 |
| Max Radio AS | Information & communication | 2012 |
| Maxim Partner AS | Hospitality | 2017 |
| Mayar AS | | 2020 |
| MB Prosjekt AS | Real estate | 2010 |
| Mc-Butikken AS | Wholesale & retail | 2021 |
| Mcbutikken Eiendom AS | Real estate | 2000 |
| MDH AS | Construction | 2022 |
| MDH Utvikling AS | Real estate | 2024 |
| Meatjønnsveien 64 AS | Real estate | 2014 |
| Meatjørna 1 AS | Real estate | 2009 |
| Meatjørna 4 AS | Real estate | 2018 |
| Mebi AS | Agriculture & fishing | 2026 |
| Mechtrade AS | Professional & scientific | 2018 |
| Medbør AS | | 2021 |
| Medgard AS | | 1997 |
| Mediehuset Haugesunds Avis AS | Information & communication | 1912 |
| Meglerhuset Rele Haugesund AS | Real estate | 2011 |
| Meglerhuset Rele Holding AS | Real estate | 2019 |
| Meglio AS | Real estate | 2024 |
| Meglio Utleie AS | Real estate | 2024 |
| Meieriet 1877 AS | Real estate | 2024 |
| Meierigården Etne AS | Real estate | 2011 |
| Mektek Vedlikehold AS | Manufacturing | 2006 |
| Melkevik Eiendom AS | Real estate | 2023 |
| Mellow Eindom AS | Real estate | 2024 |
| Men Invest AS | | 2026 |
| Men's Concept AS | Other services | 2026 |
| Mentem AS | Real estate | 2005 |
| Mentum Gruppen AS | Real estate | 2022 |
| Mentum-Eiendom AS | Real estate | 2022 |
| Meraki Invest AS | | 2025 |
| Mercator Crewing Holding AS | Administrative & support | 2020 |
| Mercator Crewing I AS | Administrative & support | 2021 |
| Mercator Services AS | Administrative & support | 2020 |
| Mercator Services II AS | Administrative & support | 2022 |
| Mercator Services III AS | Administrative & support | 2025 |
| Merryland Holding AS | Real estate | 2014 |
| Mesterbygg Vest AS | Construction | 2025 |
| Mesterli AS | Financial services | 2018 |
| Mestre Holding AS | Education | 2023 |
| Metri AS | Financial services | 2013 |
| Metri Holding AS | | 2025 |
| Mett Solutions AS | Wholesale & retail | 2026 |
| Meyerpro AS | Administrative & support | 2011 |
| MF Holding AS | Financial services | 2014 |
| MFL Holding AS | | 2022 |
| MGD Invest AS | Wholesale & retail | 2023 |
| MHL AS | Manufacturing | 2005 |
| MHL Holding AS | Financial services | 2005 |
| MHV Invest AS | Financial services | 2017 |
| Mid-As | Professional & scientific | 2010 |
| Midtun Konsult AS | Professional & scientific | 2025 |
| Mil Bil AS | Transport & logistics | 2017 |
| Milieuband Da | Arts & recreation | 2023 |
| Miljeteig Eiendom AS | Real estate | 1933 |
| Milukas AS | Wholesale & retail | 2014 |
| Mindus Holding AS | Wholesale & retail | 2016 |
| Mini Krasna AS | Hospitality | 2023 |
| Miraflora AS | Wholesale & retail | 2023 |
| Mirein AS | Real estate | 2025 |
| Mirota Bygg AS | Construction | 2024 |
| Mirø Eiendom AS | Real estate | 2014 |
| Mis Invest AS | Real estate | 2008 |
| Mistra AS | Real estate | 1998 |
| Mjuk AS | Education | 2016 |
| Mjølner Håndtverk AS | Construction | 2025 |
| MK Sissel AS | Wholesale & retail | 2019 |
| Mko Holding AS | Administrative & support | 2022 |
| Mkold AS | Professional & scientific | 2020 |
| MLD Invest AS | Wholesale & retail | 2005 |
| MM Bergen AS | Hospitality | 2023 |
| MM Haugesund AS | Hospitality | 1997 |
| MM Stavanger AS | Hospitality | 2023 |
| Mntg Invest AS | | 2024 |
| Mobeni Invest AS | Financial services | 2005 |
| Modica Holding AS | | 2026 |
| Moholt Sushi AS | Hospitality | 2022 |
| Moksheim Hage AS | Real estate | 2020 |
| Moksheim Panorama AS | Real estate | 2019 |
| Moment Service Senter AS | Manufacturing | 2018 |
| Monclair Capital AS | | 2026 |
| Moowh HMS Og Bedriftshelsetjeneste AS | Health & social care | 2013 |