| Involved Holding AS | Professional & scientific | 2024 |
| Involved Innovation AS | | 2026 |
| Iof Holding AS | | 2021 |
| Ion Holding AS | Real estate | 2017 |
| Islann Invest AS | Wholesale & retail | 2005 |
| Iso-Safe AS | Wholesale & retail | 2012 |
| Istrail AS | Wholesale & retail | 1988 |
| Istrail Gruppen AS | Wholesale & retail | 2017 |
| IT Polaris AS | Information & communication | 2008 |
| IT Source AS | Wholesale & retail | 2017 |
| Itbistand AS | Information & communication | 2007 |
| Itsos AS | Wholesale & retail | 2018 |
| Ivar Halvorsen Eiendom AS | Wholesale & retail | 2018 |
| Ivar Seim AS | Real estate | 2005 |
| Ivars Eiendom Invest AS | Real estate | 1992 |
| Ivers & Momork Holding AS | Other services | 2017 |
| Ivers E Holding AS | Real estate | 2017 |
| Izoblock Norway AS | Professional & scientific | 2021 |
| J & B Utstyr AS | Wholesale & retail | 2007 |
| J & F Mester Invest Da | Real estate | 2010 |
| J Beck Holding AS | | 2024 |
| J.A. Maskin AS | Construction | 2009 |
| J.H.H AS | | 2021 |
| J.V Tømrer Og Snekkerservice Da | Construction | 2007 |
| Jab Fighting AS | Real estate | 2022 |
| Jacobsen-Invest AS | | 2021 |
| Jade AS | | 2019 |
| Jage Eiendom AS | Real estate | 2016 |
| Jahaja Utleie AS | Real estate | 2008 |
| Jaho AS | Information & communication | 1997 |
| Jaho Eiendom AS | Information & communication | 1987 |
| Jahren Rør AS | Construction | 2026 |
| Jahrestranda Drift AS | Real estate | 2013 |
| Jahrestranda Holding AS | Real estate | 2014 |
| Jahrestranda Næringspark AS | Real estate | 1935 |
| Jajotho AS | Financial services | 2005 |
| Jakobsen Consulting AS | Professional & scientific | 2015 |
| Jam Capital AS | | 2021 |
| James Clark Eiendom AS | Real estate | 2014 |
| James Clark Pub & Restaurant AS | Hospitality | 2004 |
| Jan Fredrik Bjørntvedt AS | Professional & scientific | 2018 |
| Jangeltun Holding AS | Real estate | 2022 |
| Janihus R Nilsen AS | Wholesale & retail | 1997 |
| Jarjan Eiendom AS | Real estate | 2024 |
| JB Tjenester AS | Administrative & support | 2014 |
| Jba 24 AS | Real estate | 2020 |
| Jba 26 AS | Real estate | 2015 |
| JBL AS | Real estate | 2019 |
| JCS Eiendom AS | Real estate | 2015 |
| Je-Bygg AS | Construction | 2022 |
| Jean B Linaae AS | | 2005 |
| Jeff Holding AS | | 2021 |
| Jegersborggata 2 AS | Real estate | 2010 |
| Jeh Kapital AS | | 2026 |
| Jekra AS | Transport & logistics | 2014 |
| Jenkro Invest AS | Information & communication | 2017 |
| Jensen Og Eriksen Eiendom AS | Construction | 2018 |
| Jentsch Holding AS | | 2023 |
| Jep Bygg Og Eiendomsutvikling AS | Construction | 2015 |
| Jepø Eiendom AS | Real estate | 1996 |
| Jernbanealleen 19 AS | Real estate | 2017 |
| Jernbanealleen 28 AS | Real estate | 2015 |
| Jernbanealleen 29 AS | Real estate | 2023 |
| Jernbaneallèen 27 AS | Real estate | 2005 |
| Jernbaneallèen 27 Bolig AS | Real estate | 2019 |
| Jesa Holding AS | Professional & scientific | 2018 |
| JFS Invest AS | Real estate | 2013 |
| JH Økonomi AS | Professional & scientific | 2014 |
| Jhe-Invest AS | | 2019 |
| JHT AS | Transport & logistics | 2013 |
| Jill Holding AS | Real estate | 2008 |
| JJ Safety AS | Professional & scientific | 2007 |
| JK Cutting Services AS | Water & waste | 2023 |
| JKN Invest AS | Professional & scientific | 2022 |
| Jo Safety Norge AS | Manufacturing | 2012 |
| Jo-Invest AS | | 2022 |
| Jo.Jo AS | Real estate | 2019 |
| Joakim Johansen AS | Construction | 1987 |
| Jofrema AS | Wholesale & retail | 2018 |
| Johan Evensen & Sønner AS | Administrative & support | 1973 |
| Johan Evensen AS | | 2015 |
| Johan Evensen Eiendom AS | Real estate | 2008 |
| Jollyroom AS | Wholesale & retail | 2010 |
| Jolo AS | | 2008 |
| Joma Maskin Og Verktøyindustri AS | Manufacturing | 1984 |
| Jomfruland Bidco AS | | 2025 |
| Joron Invest AS | | 2019 |
| Jotun A/S | Manufacturing | 1971 |
| Jotun India Private Limited | Administrative & support | 2016 |
| Jotun Paints (Europe) Ltd | Professional & scientific | 2009 |
| Jotun Powder Coatings AS | Manufacturing | 1997 |
| JP Apartments AS | Real estate | 2023 |
| JP Corporation AS | Real estate | 2015 |
| JP Properties AS | Real estate | 2023 |
| JP Shipping AS | Manufacturing | 2012 |
| JP Yachts AS | Wholesale & retail | 2023 |
| JPK AS | Construction | 2013 |
| JPL Bilverksted AS | Other services | 2001 |
| Jpml Invest AS | | 2020 |
| JPS Rekonstrukcje S.C. | Construction | 2006 |