| Midgården Eiendom AS | Real estate | 2017 |
| Mikrodata AS | Information & communication | 1988 |
| Milcrossclean AS | Wholesale & retail | 2021 |
| Mile Flis AS | Construction | 2026 |
| Miljøbygg Eiendom AS | Real estate | 2022 |
| Mimmis AS | Hospitality | 2014 |
| Min Kilde AS | Other services | 2008 |
| Mind the G.A.P. AS | Administrative & support | 2013 |
| Mio Gelato AS | Manufacturing | 2024 |
| Miss Hosting AS | Information & communication | 2003 |
| MMR AS | Real estate | 2021 |
| MMR Eiendom AS | Real estate | 2021 |
| Mobile Larvik AS | Wholesale & retail | 2011 |
| Mobylinq AS | Professional & scientific | 2023 |
| Modulhytter AS | Manufacturing | 2014 |
| Mohac AS | Professional & scientific | 2022 |
| Mohagen Sandefjord AS | Real estate | 2016 |
| Moland & Sundby Stål & Sveis Ans | Real estate | 1994 |
| Moland Og Sundby AS | Manufacturing | 2001 |
| Molo Larvik AS | Hospitality | 2023 |
| Moltis Holding AS | | 2025 |
| Monarch Holding Nuf | Transport & logistics | 2017 |
| Montrex AS | Information & communication | 2025 |
| Monzonite AS | Mining & quarrying | 1984 |
| Morris Media Event Og Sceneteknikk AS | Arts & recreation | 2018 |
| Morten Lågeide Holding AS | Professional & scientific | 2026 |
| Mortvedt AS | Wholesale & retail | 2026 |
| Mothor AS | Financial services | 2015 |
| Motor Forum AS | Wholesale & retail | 1985 |
| MR Kapital AS | Manufacturing | 2012 |
| MR Økonomi AS | Professional & scientific | 2025 |
| MTB Equity AS | | 2021 |
| MTB Group AS | Real estate | 2015 |
| MTB Management AS | Real estate | 2021 |
| MTB Property AS | Real estate | 2024 |
| MTB Property Partners AS | | 2021 |
| MTD Nordic AS | Information & communication | 2015 |
| Mtyrdal Holding AS | | 2021 |
| Mulcon AS | Professional & scientific | 2018 |
| Multi Engros Ans | Wholesale & retail | 1990 |
| Multifag Holding AS | Construction | 2021 |
| Multimontasje AS | Construction | 2017 |
| Mundur AS | Professional & scientific | 2012 |
| MWS Holding AS | | 2020 |
| My Style AS | Wholesale & retail | 2026 |
| Møbelsnekker Heidi Dyrnes AS | Manufacturing | 2007 |
| Mølen Eiendom AS | Real estate | 2025 |
| Møllegata 10-12 AS | Real estate | 2017 |
| Møllen Holding AS | | 2022 |
| Møller Consult AS | Education | 2015 |
| Møller Håndverk AS | Construction | 2017 |
| Møllers Eiendom AS | Construction | 2017 |
| Møllers Holding AS | Construction | 2017 |
| N2080.NO AS | Wholesale & retail | 2010 |
| Naess Consult AS | Professional & scientific | 2025 |
| Nails & Pmu Revolution AS | Other services | 2019 |
| Nakjem Transport AS | Transport & logistics | 1996 |
| Nalini AS | Education | 2021 |
| Nannaraa AS | Real estate | 2019 |
| Nanset Blomsterverksted AS | Wholesale & retail | 2013 |
| Nanset Fysioterapi AS | Real estate | 2025 |
| Nanset Kjøkkensenter AS | Wholesale & retail | 2001 |
| Nanset Legekontor AS | Real estate | 2000 |
| Nanset Standard AS | Real estate | 2008 |
| Nanset-Hjørnet AS | Real estate | 2006 |
| Nansetgata 103-105 Larvik AS | Real estate | 2023 |
| Nansetgata 22 AS | Real estate | 1998 |
| Nansetgata 23 AS | Real estate | 2021 |
| Nansetgata 28 AS | Real estate | 2025 |
| Nansetgata 43 AS | Real estate | 2008 |
| Nansetgata 45 AS | Real estate | 2014 |
| Nansetgata 91 AS | Real estate | 2003 |
| Nansetgata AS | Real estate | 2019 |
| Nansetgaten 17 AS | Real estate | 1998 |
| Nansetveien 105 Larvik Da | Real estate | 2003 |
| Naper AS | | 2018 |
| Naphaug Invest AS | | 2025 |
| Naprapatene Tholfsen Og Steinsholt Da | Health & social care | 2018 |
| Narnia AS | Real estate | 2005 |
| Nashwan Frisør AS | Other services | 2020 |
| Nasta AS | Wholesale & retail | 1976 |
| Nasta Utleie AS | Administrative & support | 2016 |
| Natur- & Miljødata AS | Professional & scientific | 2014 |
| Naustet Invest AS | Manufacturing | 2012 |
| Naver Eiendom AS | Real estate | 1997 |
| Navi Eiendom AS | Administrative & support | 2009 |
| Nbst AS | Manufacturing | 2008 |
| Nedre Fritzøegate Eiendom AS | Real estate | 2008 |
| Nedre Gui Gård AS | Agriculture & fishing | 2021 |
| Nedre Lågen Jordvanning SA | Agriculture & fishing | 1976 |
| Nedre Verksgård AS | Real estate | 2008 |
| Nelora AS | | 2025 |
| Nemus Larvik AS | Health & social care | 2020 |
| Nensetbakken 30 AS | | 2022 |
| Nerpuz Brannsikring AS | Professional & scientific | 2023 |
| Nesjar AS | Agriculture & fishing | 1996 |
| Neste Scene AS | Arts & recreation | 2018 |
| Nette Holding AS | Real estate | 2013 |
| Nevlunghavn Event AS | Arts & recreation | 2012 |
| Newsify AS | Information & communication | 2026 |