| Iseo Invest AS | | 2023 |
| Isl AS | Professional & scientific | 2020 |
| Isorob AS | Real estate | 2012 |
| Italiensk Pizza AS | Hospitality | 2014 |
| Itamar AS | Real estate | 2016 |
| Ith Rasmussen AS | Agriculture & fishing | 2008 |
| Itvedt Holding AS | | 2026 |
| Iverk Arkitekt AS | Professional & scientific | 2022 |
| Iverk VDC AS | Professional & scientific | 2022 |
| J&L Prytz Holding AS | | 2026 |
| J-A Services AS | Other services | 2016 |
| J.E.S Drift AS | | 2011 |
| J.E.S Holding AS | | 2016 |
| J.G. Hytteutleie AS | Real estate | 2013 |
| J.H Investering AS | Real estate | 2021 |
| Jabe Investeringer AS | | 2026 |
| JAC4 AS | Real estate | 2012 |
| Jackmaster AS | Information & communication | 2019 |
| Jacobsen Konfeksjon AS | Wholesale & retail | 2004 |
| Jacobsen Marine Survey AS | Professional & scientific | 2019 |
| Jaf AS | Education | 2023 |
| Jah Invest AS | | 2015 |
| Jakobsen Energi Service AS | Wholesale & retail | 2012 |
| Jakubek Bis | Construction | 2005 |
| Jany AS | | 2026 |
| Japan Sportsbil Import Da | Wholesale & retail | 2001 |
| Jarmo AS | Construction | 2010 |
| Jarno Mal & Flis AS | Construction | 2024 |
| Jaskic Event AS | Arts & recreation | 2026 |
| Jatec AS | Construction | 1990 |
| Jav Holding AS | Real estate | 2011 |
| Javi Holding AS | Real estate | 1998 |
| JBS Eiendomsinvest AS | Real estate | 2014 |
| JBS Invest AS | Manufacturing | 2005 |
| JC Gruppen AS | Real estate | 2012 |
| JCM AS | Professional & scientific | 2023 |
| Jeako Da | Hospitality | 1989 |
| Jeanette & Rune AS | Wholesale & retail | 1999 |
| Jecons AS | Professional & scientific | 2024 |
| Jekm Holding AS | Professional & scientific | 2024 |
| Jg-Invest AS | Professional & scientific | 2008 |
| JGV Holding AS | | 2022 |
| JHR Holding AS | | 2024 |
| JHR Invest AS | Health & social care | 2015 |
| JK Bil AS | | 2020 |
| JK Episteme AS | Financial services | 2005 |
| JK Hordvik Holding AS | Professional & scientific | 2023 |
| JL Consulting AS | Professional & scientific | 2026 |
| Joak Holding AS | | 2026 |
| Joakim Dahlgren Holding AS | Health & social care | 2024 |
| Joan AS | Wholesale & retail | 2005 |
| Joan Invest AS | Wholesale & retail | 2025 |
| Joba AS | Real estate | 1990 |
| Johan Rokstad AS | Transport & logistics | 1991 |
| Johannes Østensjø & Co AS | Real estate | 1917 |
| Johannes Østensjø Dy AS | Mining & quarrying | 1990 |
| John Audun Antonsen AS | Real estate | 2013 |
| John Olas Andre Holding AS | Professional & scientific | 2022 |
| Johnny Johansen Holding AS | Transport & logistics | 2022 |
| Johs Lothe AS | Transport & logistics | 1923 |
| Jonas Frøland Eiendom AS | Real estate | 2022 |
| Jonas Frøland Holding AS | Real estate | 2024 |
| Jone's Import & Export Limited Nuf | Wholesale & retail | 2024 |
| Jone's Investment Norway Limited Nuf | | 2024 |
| Jooy SA | Administrative & support | 2025 |
| Jora Holding AS | Financial services | 2005 |
| Jordan Finans AS | Real estate | 1981 |
| Joseg AS | Transport & logistics | 2007 |
| Joso Investering AS | Real estate | 2018 |
| Jost Holding AS | Financial services | 2013 |
| Jostav Holding AS | Real estate | 2006 |
| Jota Invest AS | Real estate | 2013 |
| Jothur AS | Financial services | 2014 |
| Jov AS | Health & social care | 2019 |
| JR Mtech AS | Construction | 2008 |
| JT Invest AS | Real estate | 2008 |
| Jt-Holding AS | Financial services | 2005 |
| JTK Samdrift AS | Agriculture & fishing | 2023 |
| Julian's Barbershop AS | Other services | 2020 |
| Juma Holdings AS | Real estate | 2021 |
| JV Investering AS | | 2025 |
| Jvs-Holding AS | | 2026 |
| JWH Holding AS | | 2011 |
| Jåblom Bakst AS | Manufacturing | 2018 |
| Jåblom Invest AS | Manufacturing | 2021 |
| Jødy Eiendom AS | Real estate | 2015 |
| Jørihaugen Tomt AS | Real estate | 2023 |
| Jørre Babb AS | | 2025 |
| Jøtnaheim AS | Financial services | 2006 |
| K Johannessen Holding AS | | 2025 |
| K Kolbeinsen & Co AS | Wholesale & retail | 1926 |
| K Realinvest AS | Real estate | 2007 |
| K Vatnem Eiendom AS | Real estate | 1987 |
| K&O Holding AS | Real estate | 2015 |
| K.L. Holding AS | Construction | 2015 |
| K.R.H. Holding AS | | 2025 |
| K2 Inneklima Da | Construction | 2022 |
| K6 Invest AS | Real estate | 2017 |
| Kabe AS | Financial services | 1998 |
| Kad AS | Professional & scientific | 2023 |