| Iws Fleet Operations AS | Transport & logistics | 2025 |
| Ix PHM Invest AS | | 2025 |
| Ix Sperre Invest AS | | 2025 |
| Ixmal Intelesis AS | Information & communication | 1988 |
| Ixr Stories AS | Arts & recreation | 2025 |
| Iyuno A/S Nuf | Arts & recreation | 1995 |
| Izabela Rens AS | Administrative & support | 2026 |
| Izakaya Oslo AS | Hospitality | 2012 |
| Izbica Holdning AS | | 2019 |
| Izgara AS | Hospitality | 2025 |
| Izum Solutions AS | Professional & scientific | 2019 |
| Izy AS | Information & communication | 2019 |
| Izy Holding AS | Information & communication | 2021 |
| Ing.Erik Haarseth A/S | Wholesale & retail | 1988 |
| Ingeniørfirma ABIKO Norsk AS | Wholesale & retail | 1965 |
| Interessentskapet Jahre Line | | 1960 |
| International Business Concepts A/S | Wholesale & retail | 1988 |
| Interstrada AS | Transport & logistics | 1984 |
| Invicta AS | Professional & scientific | 1984 |
| Iøyna AS | Financial services | 2020 |
| J & C Sport AS | Wholesale & retail | 2023 |
| J a Roti | Professional & scientific | 1999 |
| J B Bakke AS | Real estate | 1952 |
| J B Malerservice Bergman | Construction | 2004 |
| J Brooker AS | | 2021 |
| J Bugge & K I Gade Ans | | 1989 |
| J E Skappel AS | Wholesale & retail | 2005 |
| J Fredrik Olsen Forvaltning AS | Real estate | 1996 |
| J G Invest AS | Real estate | 1987 |
| J Group AS | Information & communication | 2015 |
| J Gruppen AS | Real estate | 2011 |
| J Henriksen Invest AS | | 2018 |
| J Holdings AS | | 2026 |
| J Honningsvåg Invest AS | | 2020 |
| J Ibsen AS | Information & communication | 2021 |
| J K Montage I Vedevåg AB | Construction | 1997 |
| J L Bedriftassistanse AS | Professional & scientific | 1989 |
| J Monrad-Hansen AS | Wholesale & retail | 1969 |
| J N Arkitektur & Design AS | Financial services | 2005 |
| J N Capital AS | | 2020 |
| J O Nilssen AS | Wholesale & retail | 1981 |
| J Olsens Enke Eiendom AS | Real estate | 1984 |
| J P Holding AS | Real estate | 2019 |
| J P Konsulent AS | Professional & scientific | 2019 |
| J P Kristoffersen Invest AS | Wholesale & retail | 1976 |
| J Rydsaa AS | | 2026 |
| J S Cock AS | Wholesale & retail | 1955 |
| J S Cock Holding AS | Wholesale & retail | 2021 |
| J Sandvik Holding AS | Real estate | 2020 |
| J Smith Thjømøe Holding AS | | 2023 |
| J Støre Holding AS | | 2023 |
| J V Holm AS | Real estate | 2010 |
| J Ventures AS | | 2022 |
| J Wethal AS | | 2024 |
| J X S Concept Commercial Ans | Wholesale & retail | 1989 |
| J&E Capital AS | | 2026 |
| J&L Invest AS | | 2018 |
| J&M Services AS | Construction | 2019 |
| J&P Group AS | Professional & scientific | 2026 |
| J&P Invest AS | Real estate | 2018 |
| J&R Byggservice AS | Construction | 2026 |
| J&T Finans AS | | 2026 |
| J&V Dører AS | Wholesale & retail | 2023 |
| J&V Holding AS | Construction | 2025 |
| J&V Invest AS | | 2024 |
| J&V Snekkere AS | Construction | 2025 |
| J-A-M Invest AS | Health & social care | 2013 |
| J-Dogg Holding AS | | 2020 |
| J-E Holding AS | | 2014 |
| J-Fredriksen AS | | 2025 |
| J-Hr Eiendom AS | Real estate | 2021 |
| J-Hr Holding AS | | 2019 |
| J-Lo Holding AS | | 2023 |
| J-Son & Co AS | Wholesale & retail | 2000 |
| J. Aamnes AS | Professional & scientific | 2025 |
| J. Akeren Invest AS | | 2024 |
| J. Busch Holding AS | | 2026 |
| J. F. Karlsen AS | Real estate | 2007 |
| J. Finne Holding AS | Real estate | 2005 |
| J. H. Nathan Holding AS | | 2026 |
| J. Haaland Holding AS | | 2021 |
| J. Helstad AS | Professional & scientific | 2005 |
| J. K. Holding AS | | 2005 |
| J. Kleppan Holding AS | | 2025 |
| J. Manholt AS | | 2024 |
| J. Olsen AS | Real estate | 2010 |
| J. Sarwar Invest AS | | 2026 |
| J. Skjulestad Invest AS | Financial services | 2008 |
| J.A. Aagaard Invest AS | Arts & recreation | 2020 |
| J.A.M. Konsulenttjenester AS | Professional & scientific | 2000 |
| J.Ba Holding AS | | 2025 |
| J.Bakke AS | Real estate | 2016 |
| J.E. Kallerud Consult AS | Information & communication | 2016 |
| J.E.A. Varehandel AS | Wholesale & retail | 2012 |
| J.F.B Holding AS | | 2025 |
| J.F.Company AS | Other services | 2026 |
| J.F.J Invest AS | | 2026 |
| J.Hicks Johnsen Holding AS | | 2025 |
| J.J.A. Holding AS | Construction | 2023 |
| J.Jørstad AS | | 2025 |