| Kjerulfs Gate 4 AS | Real estate | 2016 |
| Kjerulfs Gate 5 Og 7 AS | Real estate | 2016 |
| Kjetilgj AS | Professional & scientific | 2018 |
| Kjøkkenmontøren S. Sørensen AS | Construction | 2019 |
| Kjøl På Hjul AS | Construction | 2025 |
| Kjøyr Holding AS | | 2025 |
| KK Elektro AS | Construction | 2025 |
| Klapaucius AS | | 2017 |
| Klar Consulting AS | Professional & scientific | 2023 |
| Klar Til Bruk AS | Administrative & support | 2024 |
| Klave Holding AS | | 2025 |
| Klavestad Invest AS | Financial services | 2006 |
| Klinikk Emilie AS | Health & social care | 2024 |
| Klinikk M AS | Health & social care | 2019 |
| KLP Invest AS | | 2020 |
| Kløfta Helsesenter AS | Real estate | 2024 |
| Kløfta Holding AS | | 2025 |
| Klüber Lubrication Nordic Nuf | Wholesale & retail | 1995 |
| Knitting Inna AS | Wholesale & retail | 2014 |
| Knowledge Invest AS | Professional & scientific | 2019 |
| Knutsmoen Eiendom Ans | Real estate | 2012 |
| Kollstrøm Holding AS | Professional & scientific | 2021 |
| Komét Trafikkskole AS | Education | 2013 |
| Konrad Bråthen AS | Real estate | 1963 |
| Konseptpluss AS | Real estate | 2011 |
| Konsulent Økonomi AS | Professional & scientific | 2023 |
| Konterud Dagligvare AS | Wholesale & retail | 2023 |
| Kontor Renhold AS | Administrative & support | 2001 |
| Korshagen Pizza AS | Hospitality | 2022 |
| Kp&Ba Invest AS | | 2025 |
| Kraftek AS | Administrative & support | 2021 |
| Krankontrollen AS | Professional & scientific | 1993 |
| Krav Maga Instituttet AS | Professional & scientific | 2012 |
| Kreativlogoped AS | Health & social care | 2022 |
| Kreftkompasset AS | Health & social care | 2018 |
| Krem AS | | 2025 |
| Kristin Wahl Holding AS | Financial services | 2016 |
| Kritrofro Invest AS | | 2022 |
| Kskb Holding AS | | 2025 |
| Ksund Holding AS | | 2025 |
| Kulturkvartalet Lillestrøm AS | Real estate | 2017 |
| Kursiv Media AS | Manufacturing | 1999 |
| Kursmed AS | Information & communication | 2025 |
| Kvartal 1 AS | Real estate | 2016 |
| Kvartal 26 Utbygging AS | Real estate | 2017 |
| Kvartal 32 Utbygging AS | Real estate | 2017 |
| Kvartal 33 AS | Real estate | 2010 |
| Kvartal 6 Holding AS | | 2026 |
| Kvartal 8 Bolig AS | Real estate | 2018 |
| Kveck AS | Information & communication | 2026 |
| Kvernevik Holding AS | | 2026 |
| Kvernstua Utleieboliger AS | Real estate | 2022 |
| Kvikkere Hoder Rekruttering AS | Administrative & support | 2023 |
| Kværnstua AS | Real estate | 2017 |
| Køhnkvartalet AS | Real estate | 1998 |
| Køhns AS | Real estate | 1973 |
| La Bella AS | Other services | 2021 |
| Laderiet Da | Wholesale & retail | 2008 |
| Lady Solskjerming AS | Manufacturing | 1976 |
| Lajan Invest AS | | 2012 |
| Lakh AS | | 2026 |
| Lama Investment AS | | 2023 |
| Lammers AS | Real estate | 2013 |
| Landfast Utleie AS | Administrative & support | 2026 |
| Landsome AS | Real estate | 2022 |
| Landstads Gate 2 AS | Real estate | 2016 |
| Langentangen Invest AS | Financial services | 2016 |
| Lasse Liten Leker AS | Wholesale & retail | 1992 |
| Lat Holding AS | Financial services | 2005 |
| Laudi AS | Information & communication | 2011 |
| Laukas Elektriske AS | Construction | 1997 |
| Laukas Elektriske Prosjekt AS | Construction | 2024 |
| Laukas Invest AS | Construction | 2023 |
| Laukas Maskin AS | Administrative & support | 2025 |
| Laukas Prosjekt AS | Construction | 2021 |
| Laukas VVS AS | Construction | 2025 |
| Laurentius Consult AS | Education | 2022 |
| Leancon AS | Professional & scientific | 2013 |
| Learnist AS | Education | 2020 |
| Ledang Health AS | Health & social care | 2014 |
| Lege 1 AS | Health & social care | 2019 |
| Lege Canh Le Nygaard AS | Health & social care | 2014 |
| Lege Pål Jeroen Husby AS | Health & social care | 2020 |
| Legekraft AS | Health & social care | 2023 |
| Legesenter AS | Health & social care | 2026 |
| Leiden Invest AS | Real estate | 2006 |
| Leira Holding AS | Real estate | 2021 |
| Lepore Holding AS | | 2025 |
| Let's Learn Trafikkskole AS | Education | 2015 |
| Level 9 AS | Professional & scientific | 2019 |
| Leverage AS | Wholesale & retail | 2018 |
| Levitator AS | Education | 2023 |
| Lfi Helse & Trening AS | Real estate | 2002 |
| Libanon Mat AS | Hospitality | 2018 |
| Lila Market AS | Wholesale & retail | 2023 |
| Lille Bryggeri AS | Manufacturing | 2025 |
| Lille Bryggeri Assets AS | Real estate | 2024 |
| Lille Elve Vann- Og Avløpslag SA | Water & waste | 2012 |
| Lille Potteri AS | Manufacturing | 2023 |
| Lille Smil AS | Health & social care | 2025 |