| KL Byggtjeneste AS | Construction | 2013 |
| Klimavent Holding AS | | 2025 |
| Klinikk for Fysioterapi AS | Health & social care | 2017 |
| Knattås AS | Real estate | 2019 |
| Kokosbollefabrikken AS | Manufacturing | 2010 |
| Kongsrød Holding AS | | 2022 |
| Kortbølgen Holding AS | Real estate | 2022 |
| Kristianbo AS | Health & social care | 2026 |
| Krogstadfjorden Eiendomsutvikling AS | Construction | 2002 |
| Krogstadfjorden Va SA | Water & waste | 2020 |
| Krogstadfjorden Va Utbygging SA | Water & waste | 2020 |
| Krogstadveien 2 AS | Real estate | 2025 |
| Kron Dental AS | Health & social care | 2021 |
| Kuba CG AS | | 2025 |
| Kuldetek AS | Construction | 2003 |
| Kvalitetshus AS | Construction | 2025 |
| Land of Hope Music AS | Information & communication | 2022 |
| LB Ur Og Gull Holding AS | Wholesale & retail | 2018 |
| Legenmin.No AS | Health & social care | 2005 |
| Leidalen Holding AS | | 2018 |
| Lien Autoinvest AS | Wholesale & retail | 2022 |
| Lilly Agency AS | Professional & scientific | 2025 |
| Linda Fredriksen Invest AS | | 2026 |
| Lippert Holding AS | Real estate | 2008 |
| Lta AS | | 2018 |
| Lucky Look AS | Other services | 2012 |
| Lund Hundetjenester AS | Other services | 2013 |
| Lundeborg Vanningsanlegg SA | Water & waste | 2021 |
| Lundeby Gartneri AS | Agriculture & fishing | 2022 |
| Lundeby Utleie AS | Real estate | 2023 |
| M a Eiendom AS | Agriculture & fishing | 2006 |
| M Marketing AS | Professional & scientific | 2019 |
| Mac Capital AS | Transport & logistics | 2024 |
| Mac Utvikling AS | Real estate | 2019 |
| Mariannes Brodering AS | Professional & scientific | 2016 |
| Markos Båtservice AS | Manufacturing | 2020 |
| Marstein IT AS | Information & communication | 2024 |
| Mazar Service AS | Transport & logistics | 2023 |
| Mcservice.No AS | Wholesale & retail | 2022 |
| Melow AS | Information & communication | 2024 |
| Mesterhandtverkerne Da | Construction | 2012 |
| Meta Regnskap AS | Professional & scientific | 2023 |
| Mettes Bilconsult AS | Wholesale & retail | 2024 |
| MF Eiendom AS | Real estate | 2010 |
| Miamar Invest AS | | 2021 |
| Mikkelrud Bil AS | Wholesale & retail | 2012 |
| Missingmyr Barnehage AS | Education | 2007 |
| Missingmyrveien 16 AS | Real estate | 1967 |
| MK Auto AS | Other services | 2019 |
| Mm-H Holding AS | | 2026 |
| Mopedbil Norge AS | Wholesale & retail | 2011 |
| Morunn Holding AS | Real estate | 2012 |
| Moss Elektroinstallasjon AS | Construction | 2013 |
| Moss Entreprenør AS | Construction | 2015 |
| N & R Holding AS | | 2007 |
| Nedre Glomma Drift AS | Administrative & support | 2023 |
| Need to Clean AS | Administrative & support | 2015 |
| New Wave Norway AS | Wholesale & retail | 1988 |
| Nicolaysen Anlegg Og Transport AS | Transport & logistics | 1992 |
| Nitho Eiendom AS | Real estate | 2025 |
| Nor Foods AS | Manufacturing | 2020 |
| Nordic Bird AS | Wholesale & retail | 2021 |
| Nordlys Motor AS | Wholesale & retail | 2025 |
| Norges Auto AS | Wholesale & retail | 2020 |
| Norges Båtsenter AS | Wholesale & retail | 2023 |
| Norsk Tungbilservice AS | Other services | 2021 |
| Nortrac Nuf | Professional & scientific | 2015 |
| Norum Bobilgården AS | Wholesale & retail | 2013 |
| Norwegian Scaffold Group AS | Administrative & support | 2012 |
| NSG Group AS | Construction | 2023 |
| NSG Holding AS | Construction | 2018 |
| NXT Tech Holding AS | | 2025 |
| Ocras Invest AS | | 2025 |
| Oki Invest AS | Real estate | 2024 |
| Oksnøen Holding AS | Arts & recreation | 2005 |
| Oksnøen Leir Ans | Education | 1997 |
| Oksnøen Leir AS | Education | 2025 |
| Olimb Anlegg AS | Construction | 2011 |
| Olimb Eiendom AS | Real estate | 2011 |
| Olimb Group AS | Construction | 2011 |
| Olimb Holding AS | Construction | 2011 |
| Olimb Rørfornying AS | Construction | 2011 |
| Olimb Rørfornying Holding AS | Professional & scientific | 2017 |
| Olsen Blikk & Montasje AS | Construction | 2014 |
| ON24 Østfold AS | Professional & scientific | 2024 |
| Opplæringskontoret Bilfag Østfold AS | Education | 1995 |
| Orelien Eiendom AS | Financial services | 2005 |
| Oslofjorden Bygg AS | Construction | 1996 |
| Outback AS | Wholesale & retail | 2023 |
| Palleservice AS | Wholesale & retail | 2022 |
| Pat Vaskehjelp Østfold AS | Administrative & support | 2019 |
| Peder Eiendom AS | Real estate | 2017 |
| Pelly Kvartalet AS | Real estate | 2007 |
| Per Dahle Invest AS | Professional & scientific | 2022 |
| Permanent Studio AS | Other services | 2023 |
| Petersheim Collectibles AS | Wholesale & retail | 2024 |
| Petersheim Holding AS | Wholesale & retail | 2020 |
| Petersheim Invest AS | Wholesale & retail | 2017 |
| PLM Invest AS | Financial services | 2005 |
| Pluseight System Aktiebolag Nuf | Professional & scientific | 2019 |