| Massterly AS | Professional & scientific | 2018 |
| Master Surgery Systems AS | Wholesale & retail | 2009 |
| Matfestivalene AS | Arts & recreation | 2015 |
| Mathuset Horten AS | Wholesale & retail | 2012 |
| MBC Transport AS | Transport & logistics | 2024 |
| MC 4U AS | Wholesale & retail | 2020 |
| MCD Eiendom AS | Real estate | 1988 |
| Mectro AS | Manufacturing | 1995 |
| Medimatic AS | Information & communication | 2009 |
| Medisinsk Hudhelse AS | Health & social care | 2015 |
| Meisdal Holding AS | | 2024 |
| Meko Fitness AS | Education | 2024 |
| Melgro Holding AS | | 2022 |
| Melgård Psykologtjeneste AS | Health & social care | 2021 |
| Merk-Kjeden AS | Professional & scientific | 2006 |
| Merkantil AS | Wholesale & retail | 1976 |
| Mesbu Holding AS | | 2024 |
| Mestringslegen AS | Health & social care | 2021 |
| Meta Consulting AS | Construction | 2023 |
| Mette & Wictor Leonard Faanes | | 1990 |
| Mewa Holding AS | Professional & scientific | 2016 |
| Microways AS | Information & communication | 2025 |
| Midgard Eiendom Invest AS | Real estate | 2015 |
| Midgard Mur Betong AS | Construction | 2023 |
| Midgard Mur Holding AS | Construction | 2022 |
| Miretu Holding AS | | 2025 |
| Miretu Rør & Sveis AS | Manufacturing | 2025 |
| Mirin Sushi AS | Hospitality | 2024 |
| Mironor Eiendom Ans | Real estate | 2008 |
| Mistel Accounting AS | Professional & scientific | 2018 |
| MJ Consulting AS | Financial services | 2005 |
| Mjedo Eiendom AS | Real estate | 2012 |
| MKK Transport Horten AS | Transport & logistics | 2025 |
| ML Bildeler Da | Wholesale & retail | 2024 |
| Modular Cylinder Systems AS | Manufacturing | 2011 |
| Moe Ur Og Klokkeservice AS | Other services | 2026 |
| Moen Elektro AS | Other services | 2016 |
| Mogens AS | | 2023 |
| Moloveien Utvikling AS | Real estate | 2017 |
| Montessori Horten AS | Education | 2023 |
| Montivo AS | Construction | 2025 |
| Morgan Dental AS | | 2018 |
| Morten Og Therese Transport Da | Transport & logistics | 2011 |
| Moss Multi AS | Construction | 2024 |
| Multiluft AS | Construction | 2016 |
| Multiluft Holding AS | Construction | 2016 |
| Multiluft Invest AS | Construction | 2016 |
| Munthe Lund & Co Ans | Other services | 1974 |
| Musikalen Start SA | Arts & recreation | 2025 |
| Mutek AS | Administrative & support | 2012 |
| Myskills Da | Information & communication | 2019 |
| N2N Holding AS | Health & social care | 2021 |
| Na-Bygg AS | Construction | 2020 |
| NANA2 AS | Hospitality | 2021 |
| Napoli AS | Hospitality | 1998 |
| Navy Race AS | Administrative & support | 2018 |
| Nedre Langgate 50 AS | Real estate | 2020 |
| Nesco Agenturer AS | | 2026 |
| Nesco International AS | Wholesale & retail | 2012 |
| Netsales AS | Wholesale & retail | 2014 |
| Neva Holding AS | Professional & scientific | 2024 |
| Neva Marine AS | Wholesale & retail | 2024 |
| Neva Water AS | Professional & scientific | 2021 |
| Neverbu Holding AS | | 2026 |
| New Vision AS | Professional & scientific | 1995 |
| New Vision Group AS | Real estate | 2005 |
| Nextx AS | Real estate | 2020 |
| NFH 260513 AS | | 2026 |
| Nilcon AS | Professional & scientific | 1987 |
| Nilsen Elektro AS | Construction | 1990 |
| Nivo Invest AS | Professional & scientific | 2017 |
| Njól Design Da | Professional & scientific | 2015 |
| Nomadictwinz AS | Professional & scientific | 2025 |
| Norautron AS | Manufacturing | 1989 |
| Norautron Group Holding AS | | 2025 |
| Norautron Mechanics Holdco AS | Professional & scientific | 2020 |
| Nordbygården Ans | Real estate | 1999 |
| Nordic Adventure Van AS | Wholesale & retail | 2024 |
| Nordic Consulting AS | Professional & scientific | 2012 |
| Nordic Multiforms AS | Information & communication | 2020 |
| Nordigi AS | Information & communication | 2016 |
| Nordre Enggate 13 AS | Real estate | 2018 |
| Norges Hundefrisørskole AS | Other services | 2019 |
| Norgesglass AS | Real estate | 2005 |
| Normaritim AS | Professional & scientific | 1975 |
| Norprofil AS | Professional & scientific | 2000 |
| Norse Financial AS | Professional & scientific | 2019 |
| Norsense AS | Professional & scientific | 2007 |
| North Feed AS | Wholesale & retail | 2011 |
| Northern Lights Web AS | Information & communication | 2023 |
| Norwegian Institute for Montessori Outreach Nimo AS | Education | 2020 |
| Norwegianhobo Invest AS | | 2020 |
| Notting Hill AS | Real estate | 2012 |
| Noéa - Hud Og Estetikk AS | Other services | 2026 |
| Nummer Ti AS | Hospitality | 2023 |
| Nylund Bygg Og Maling AS | Construction | 2024 |
| Næringslivportalen Da | Information & communication | 2004 |
| Ofa Invest AS | Financial services | 2005 |
| Ogs AS | Information & communication | 2013 |
| Olsens Enke Horten AS | Wholesale & retail | 2018 |