| Ka.Invest AS | | 2026 |
| Kaldt Og Varmt AS | Construction | 2016 |
| Kalenderforlaget AS | Information & communication | 1991 |
| Kang AS | | 2021 |
| Karenslyst Årgang 2008 III AS | Financial services | 2008 |
| Kari Fagerholm Holding AS | Financial services | 2015 |
| Keyx AS | Information & communication | 2017 |
| Kingdom Holding AS | Information & communication | 2008 |
| Kirchner Holding AS | Manufacturing | 2013 |
| Kirkegata 1 Askim AS | Real estate | 2025 |
| Kirkegata Eiendom AS | Real estate | 2025 |
| Kjelen Catering AS | Hospitality | 2008 |
| Kjellerspesialisten AS | Construction | 2018 |
| Kjeserud Holding AS | Real estate | 2005 |
| Kjøpmannsgata 31 AS | Real estate | 2005 |
| KK Vent AS | Construction | 2026 |
| Klima Boligventilasjon AS | Construction | 2022 |
| Klixon Johansen & Paulsen Da | Wholesale & retail | 2002 |
| Klævold Eiendom AS | Real estate | 2013 |
| Knarfern AS | | 2025 |
| Kode.Cc AS | Information & communication | 2017 |
| Kolstad AS | | 2026 |
| Kolumbiegg AS | Wholesale & retail | 2020 |
| Kommunion AS | Information & communication | 2000 |
| Konsulent Bjarne Eriksen AS | Professional & scientific | 2017 |
| Kontorservice Lyskopi Da | Administrative & support | 1987 |
| Korsegården Mat AS | Wholesale & retail | 2025 |
| KPG7 AS | Real estate | 2025 |
| Kran Service AS | Transport & logistics | 2021 |
| Kransekakebakeren AS | Manufacturing | 2018 |
| Kranz Frisør AS | Other services | 2001 |
| Krkela AS | Wholesale & retail | 2023 |
| Krogh Eiendom AS | | 1987 |
| Krystall Renhold AS | Administrative & support | 2025 |
| KSL Auto AS | Wholesale & retail | 2020 |
| KSL Auto Holding AS | Wholesale & retail | 2021 |
| Kvalifisert Gjetting AS | | 2026 |
| Kvikju AS | Real estate | 2008 |
| Kvisler&Grimeland Sprinkler AS | Construction | 2022 |
| Landbrukstjenester Indre Østfold SA | Agriculture & fishing | 1995 |
| Large Amounts AS | | 2026 |
| Laserpunkt AS | Construction | 2024 |
| Lass AS | Information & communication | 2026 |
| Lead Marketing AS | Professional & scientific | 2025 |
| Leinebø Seljås Invest AS | | 2020 |
| Len Consulting AS | Information & communication | 2011 |
| Lenba AS | | 2021 |
| Lia Investments AS | | 2024 |
| Linera AS | Construction | 2023 |
| Linjo AS | | 2026 |
| Link Connect AS | Manufacturing | 1979 |
| Link Industrier Ans | | 1995 |
| Link Nordic AS | Information & communication | 1984 |
| Lisepe AS | Wholesale & retail | 2014 |
| Lite AS | Construction | 2011 |
| Literally AS | Information & communication | 2025 |
| Logopedsenteret AS | Health & social care | 2021 |
| Luftteknikeren AS | Construction | 2014 |
| Lugg AS | Other services | 2005 |
| Lukra AS | Real estate | 2005 |
| Lukra Holding AS | Other services | 2024 |
| Lukra Utvikling AS | Real estate | 2025 |
| Lukra Veiledning AS | Other services | 2021 |
| Lunde Inneklima AS | Construction | 2021 |
| Lune AS | Wholesale & retail | 2012 |
| LW Advokatfirma AS | Professional & scientific | 2025 |
| Lysetun Eiendom AS | Real estate | 2012 |
| Lysne Bil AS | Wholesale & retail | 2022 |
| Løken Og Helle Eiendom AS | Real estate | 2002 |
| Løken Terrasse AS | Real estate | 2019 |
| Løkenveien 12 AS | Real estate | 2024 |
| Løkenveien 8 AS | Real estate | 2022 |
| Løkenveien 8 Holding AS | Real estate | 2016 |
| Lønnveien 11 AS | Real estate | 2022 |
| Løvestad Eiendom AS | Real estate | 2005 |
| Løviks R&D AS | Professional & scientific | 2000 |
| Løvtangen Fysioterapi AS | Health & social care | 2015 |
| M and M AS | Construction | 2022 |
| Madian Holding AS | Professional & scientific | 2001 |
| Mailund 1 AS | Real estate | 2014 |
| Mako-Invest AS | Construction | 1996 |
| Maler & Våtrom AS | Construction | 2024 |
| Malermester Hoff AS | Construction | 1991 |
| Malermester Okshovd AS | Construction | 2024 |
| Malika Keys AS | Information & communication | 2016 |
| Margrethe Janbu Dressage AS | Education | 2019 |
| Maria Carlsson AS | Professional & scientific | 2024 |
| Marius Fossum Transport AS | Transport & logistics | 2020 |
| Marius Snekker Service AS | Construction | 2012 |
| Marki Holding AS | Financial services | 2018 |
| Martin Svendsen AS | | 2021 |
| Matfold AS | Arts & recreation | 2013 |
| Mathiassen Holding AS | Real estate | 2005 |
| Megapulse Australia Pty Ltd | Wholesale & retail | 2008 |
| Mekong Event AS | Administrative & support | 2026 |
| Membranspesialisten AS | Construction | 2013 |
| Memo Twins AS | Wholesale & retail | 2006 |
| Menopauseklinikken for Deg AS | Health & social care | 2023 |
| Mentalskolen AS | Education | 2015 |
| Mett AS | Wholesale & retail | 2020 |