| Irisinfo AS | Information & communication | 2008 |
| Irj Holding AS | Financial services | 2015 |
| Irkhoj AS | Financial services | 2006 |
| Irl Solutions AS | Information & communication | 2021 |
| Irlands Turistkontor | Administrative & support | 2000 |
| Irm | Professional & scientific | 2007 |
| Irma Forvaltning AS | Real estate | 2018 |
| Irmus Uab | Construction | 2005 |
| Iroh Invest AS | | 2022 |
| Iron Capital AS | Professional & scientific | 2017 |
| Iron Horse Holdco AS | | 2025 |
| Iron Standard AS | Arts & recreation | 2026 |
| Iron Wolf AS | | 2020 |
| Ironsight Norway AS | | 2024 |
| Ironsteel Scandinavia AS | Professional & scientific | 2020 |
| Ironstone AS | Information & communication | 2016 |
| Ironstone Holding AS | Information & communication | 2019 |
| Irra Mardal Butikkdrift AS | Wholesale & retail | 2018 |
| Irradia Norge AS | Wholesale & retail | 1992 |
| Irrsea AS | Manufacturing | 2021 |
| Irrupt AS | | 2020 |
| Irs Recruitment | Administrative & support | 2012 |
| Irt Invest AS | | 2026 |
| Iruption AS | Information & communication | 2021 |
| Iryna Ponomareva Holding AS | | 2023 |
| Is Admin AS | Professional & scientific | 2013 |
| Isa Group Holding AS | Construction | 2008 |
| Isa Holding AS | | 2025 |
| Isa Invest AS | Financial services | 2005 |
| Isa Nordic AS | Transport & logistics | 2017 |
| Isa Norge AS | Wholesale & retail | 2010 |
| Isaak Blå Transport AS | Transport & logistics | 2025 |
| Isabel AS | Real estate | 2005 |
| Isabella Jewellery AS | Wholesale & retail | 2017 |
| Isabelle Eriksen AS | Professional & scientific | 2019 |
| Isabelle Frisør Holding AS | Other services | 2015 |
| Isabelle Holding AS | | 2022 |
| Isabo Invest AS | Real estate | 2020 |
| Isachsen Technology & Art AS | Real estate | 1990 |
| Isak Capital AS | | 2021 |
| Isak Film AS | Information & communication | 2019 |
| Isak Ueland AS | Arts & recreation | 2023 |
| Isakjordet Invest AS | Manufacturing | 2017 |
| Isaksen & Seim Evensen Da | Administrative & support | 2003 |
| Isakveien AS | Real estate | 2007 |
| Isan Holding AS | | 2020 |
| Isandi Konsept AS | Wholesale & retail | 2003 |
| Isanor AS | Administrative & support | 2021 |
| Isanor Capital AS | | 2025 |
| Isanor Holding AS | | 2025 |
| Isanor Invest AS | Real estate | 2005 |
| Isar AS | Financial services | 2007 |
| Isar Invest AS | Financial services | 2015 |
| Isasund AS | | 2024 |
| Isave AS | Information & communication | 2005 |
| Isay Norge AS | Wholesale & retail | 2008 |
| Isbit.No AS | Manufacturing | 2025 |
| Isblikk AS | | 2022 |
| Isbre Media AS | Professional & scientific | 2016 |
| Isc AS | Professional & scientific | 2024 |
| Ischias Invest AS | Real estate | 2023 |
| Ischitani AS | | 2026 |
| Isco Group AS | Professional & scientific | 1990 |
| Isdal AS | Professional & scientific | 2007 |
| Isdalen AS | Wholesale & retail | 1990 |
| Isdammen 25 AS | Real estate | 2026 |
| Isee Communications AS | Professional & scientific | 2000 |
| Iselin Larsen Holding AS | Professional & scientific | 2023 |
| Iselin Næss AS | Professional & scientific | 2020 |
| Iselin Steiro AS | Professional & scientific | 2025 |
| Isentra AS | | 2025 |
| Isfjord Transport AS | Transport & logistics | 2025 |
| Isfjorden AS | Real estate | 2013 |
| Isg Newco AS | | 2025 |
| Isg Stavanger AS | | 2025 |
| Ishaar Eiendom AS | Real estate | 2026 |
| Ishaq Mat AS | Wholesale & retail | 2025 |
| Ishavshotellet Eiendom AS | Real estate | 1994 |
| Ishe Invest AS | | 2024 |
| Ishnoor & Dishaan AS | Hospitality | 2012 |
| Ishnoor & Dishaan Avd. Lambertseter AS | Hospitality | 2018 |
| Ishoel Holding AS | | 2025 |
| Ishopping Da | Information & communication | 2011 |
| Ishtar Bidco Norway AS | | 2019 |
| Ishus AS | Professional & scientific | 2021 |
| Isim AS | | 2018 |
| Isipisi AS | Professional & scientific | 2014 |
| Isiscreen AS | Information & communication | 2019 |
| Isj AS | Financial services | 2020 |
| Isjon AS | Information & communication | 2026 |
| Iskaa AS | Professional & scientific | 2017 |
| Iskanten Holding AS | | 2024 |
| Isko Innkvartering AS | Hospitality | 2012 |
| Isku Interiør AS | Wholesale & retail | 1992 |
| Iskyene AS | Wholesale & retail | 2018 |
| Island Champion AS | Transport & logistics | 2024 |
| Islandpig AS | Real estate | 2010 |
| Islandsgate 12 AS | Real estate | 1995 |
| Islandsgaten 9 AS | Households | 1920 |
| Islandur Rør AS | Construction | 2021 |