| J. E. Halvorsen AS | Administrative & support | 2004 |
| J.Hanssen Holding AS | | 2024 |
| Jaco Service AS | Construction | 2012 |
| Jajje Holding AS | Professional & scientific | 2016 |
| Jamroz Transport AS | Transport & logistics | 2015 |
| Japut AS | Financial services | 2005 |
| Jask Holding AS | Construction | 2021 |
| JD Proff Bygg AS | Construction | 2022 |
| Jeal Invest AS | | 2019 |
| Jensen VVS AS | Construction | 2008 |
| Jenssen Mobility AS | Transport & logistics | 2011 |
| JMK AS | Other services | 2021 |
| Joga AS | Financial services | 2015 |
| Join Animation Studio AS | Professional & scientific | 2020 |
| Jon Olsen Fysio AS | Health & social care | 2015 |
| Jonassen Holding AS | | 2014 |
| Jonssen Holding AS | Manufacturing | 2024 |
| Joshua King Football Academy AS | Administrative & support | 2020 |
| Just Kidding Da | Education | 2016 |
| Just Padel Øst AS | Real estate | 2022 |
| Jøndal Holding AS | Manufacturing | 1983 |
| K. Hansen Invest AS | Wholesale & retail | 2018 |
| Kaisers AS | Professional & scientific | 2023 |
| Karapinar Eiendom & Invest AS | | 2025 |
| Karlsen Tak Og Membran AS | Construction | 2026 |
| Kat Consulting DC AS | Professional & scientific | 2024 |
| Kat Group AS | Professional & scientific | 2022 |
| Kavalli AS | Wholesale & retail | 2017 |
| Keser Invest AS | | 2019 |
| Kezo Montasje AS | Construction | 2022 |
| KG Design AS | Arts & recreation | 2026 |
| KHH Holding AS | Wholesale & retail | 2021 |
| Kingo Rides AS | Transport & logistics | 2024 |
| Kjelka Eiendom & Invest AS | Financial services | 2005 |
| Kjøreklar Trafikkskole AS | Education | 2023 |
| Klara Olava Holding AS | | 2020 |
| Klingtech AS | Information & communication | 2023 |
| Kloppaveien 10 Eiendom AS | Real estate | 2016 |
| Kobber Eiendom Da | Real estate | 1998 |
| Kobber Invest AS | Real estate | 2006 |
| Komasi AS | Transport & logistics | 2025 |
| Kongsberg Sør AS | Real estate | 2013 |
| Konsept Boligstyling AS | Professional & scientific | 2023 |
| Konsept Byggservice AS | Construction | 2022 |
| Kra Invest AS | | 2018 |
| Kreon Engineering AS | Professional & scientific | 1998 |
| Krical AS | Financial services | 2017 |
| Krisivo AS | Information & communication | 2025 |
| Kristin Løkken AS | Professional & scientific | 2020 |
| KRM AS | Education | 1996 |
| Krokryggen AS | Real estate | 2012 |
| Kulturbruket AS | Real estate | 2018 |
| Kulturvikarene AS | Administrative & support | 2026 |
| Kverne Holding AS | Real estate | 2021 |
| Kvikk.Life AS | Education | 2018 |
| KWL Holding AS | Wholesale & retail | 2014 |
| L. Hole Holding AS | | 2024 |
| Lars Kjønniksen Holding AS | Financial services | 2017 |
| Letvik Invest AS | Wholesale & retail | 2020 |
| LEVERAGE51 AS | Professional & scientific | 2012 |
| Lifezline AS | Information & communication | 2020 |
| Liger Consulting AS | Professional & scientific | 2022 |
| Limh AS | | 2023 |
| Linder Holding AS | Real estate | 2005 |
| Linje Eiendom 2 AS | Real estate | 2019 |
| Linje Holding 1 AS | Construction | 2022 |
| Linje Holding 2 AS | | 2022 |
| LK Investor AS | | 2023 |
| Lukasz Snekkerservice AS | Construction | 2023 |
| Luna Familiebarnehage Fjellhamar AS | Education | 2022 |
| Lundvegen 2-4 Geilo AS | Education | 2014 |
| Lune Rom AS | Wholesale & retail | 2025 |
| Lungelegene I Pilestredet AS | Health & social care | 2023 |
| Lyd Og Bildehjelpen AS | Other services | 2014 |
| Lyngra Invest AS | Real estate | 2013 |
| Lørenskog Bilskadesenter AS | Other services | 2010 |
| Lørenskog Byggservice AS | Construction | 1987 |
| Lørenskog Dyrebutikk AS | Wholesale & retail | 2019 |
| Lørenskog Legesenter Da | Health & social care | 2007 |
| Lørenskog Mur & Flis AS | Construction | 2015 |
| Lørenskog Trafikkskole AS | Education | 2016 |
| Løvåsmoen Montasje AS | Construction | 2013 |
| Ma Transport AS | Transport & logistics | 2021 |
| Mab Eiendom Invest AS | Real estate | 2025 |
| Mab Holding Invest AS | | 2025 |
| Madrass Eksperten AS | Wholesale & retail | 2001 |
| Make Eiendomsutvikling AS | Real estate | 2023 |
| MALING & STILLAS ANS Kolbjørn og Karstein Arentzen | Administrative & support | 1984 |
| Man Truck & Bus Norge AS | Wholesale & retail | 1979 |
| MBH Invest AS | Financial services | 2008 |
| Mekong Catering AS | Hospitality | 2025 |
| Mekong Invest AS | Real estate | 2024 |
| Mel Heia 24 AS | Real estate | 2022 |
| Mer Holding AS | | 2019 |
| Micheletveien 28 AS | Real estate | 2019 |
| Micro Flight Teknikk AS | Wholesale & retail | 2020 |
| Milron Data Da | Information & communication | 1992 |
| Mirem AS | Real estate | 2023 |
| MK Tekniske AS | Construction | 2014 |
| MKF Vision Invest AS | Health & social care | 2025 |