| Iris Norway AS | Wholesale & retail | 2026 |
| Is-Boksen AS | Wholesale & retail | 2022 |
| Isabel Raad AS | Arts & recreation | 2016 |
| Isabella Og Sigurd Import Ans | Wholesale & retail | 1993 |
| Isava Holding AS | | 2021 |
| Isbygg AS | Construction | 2026 |
| Isdisken AS | Hospitality | 2007 |
| Isdn AS | Wholesale & retail | 2021 |
| Ishavsfisk Ans | Wholesale & retail | 1999 |
| Islandske Produkter AS | Wholesale & retail | 2015 |
| Islandwind AS | Financial services | 2018 |
| Isolde Invest AS | Education | 1998 |
| Isotrout Invest AS | | 2024 |
| Isp AS | Wholesale & retail | 2025 |
| Istenersen Holding AS | Financial services | 2018 |
| Isync AS | Information & communication | 2026 |
| IT Gruppen AS | Professional & scientific | 2024 |
| IT Line Speedlink Da | Information & communication | 1995 |
| IT Pedagogene Ans | Information & communication | 2002 |
| IT Regnskap AS | Professional & scientific | 2010 |
| It-Konsulentfirma Henrik Engebø AS | Information & communication | 2016 |
| IT2SOLVE AS | Information & communication | 2024 |
| Itase AS | Information & communication | 2022 |
| Iteco AS | Information & communication | 1997 |
| Iteum AS | Financial services | 2005 |
| Itlution AS | Professional & scientific | 2000 |
| Itm Technologies AS | Information & communication | 2021 |
| Itp Invest AS | Real estate | 2019 |
| Itrox Web Design Agder Ans | Information & communication | 1998 |
| Its Group AS | Wholesale & retail | 2017 |
| Ivar Mjåland AS | Real estate | 2001 |
| Ivar Mjåland Eiendom AS | Real estate | 1984 |
| Ivar Mjåland Holding AS | Real estate | 1983 |
| Ivar Wennerberg AS | Real estate | 1990 |
| Iveland Veteranvogn Klub Ans | Real estate | 2004 |
| Iver Invest AS | Real estate | 2005 |
| Iversen Invest AS | Real estate | 2005 |
| Ivillmark AS | Arts & recreation | 2019 |
| Ivio AS | Information & communication | 2016 |
| Ix Invest AS | | 2024 |
| J Bygg AS | Real estate | 2019 |
| J Fredriksen Holding AS | | 2025 |
| J Herlofsen Holding AS | | 2021 |
| J. E. Røsstad Bilverksted AS | Other services | 2021 |
| J. Hjorth Holding AS | | 2020 |
| J. Moe Holding AS | | 2026 |
| J.A.L Transport AS | Transport & logistics | 2025 |
| J.L Invest AS | Administrative & support | 2022 |
| J.Ws Da | Other services | 2024 |
| Ja Ma AS | Real estate | 2008 |
| Ja-Pe Eiendom AS | Real estate | 2022 |
| Jac & Em Holding AS | Information & communication | 2005 |
| Jac & Em Sports AS | | 2025 |
| Jac Invest AS | Real estate | 2011 |
| Jacek Bilservice AS | Other services | 2022 |
| Jacobsen Bygg & Design AS | Professional & scientific | 2023 |
| Jacobsen Konsulentfirma AS | Professional & scientific | 2023 |
| Jadri AS | Hospitality | 2021 |
| Jaf Eiendom AS | Real estate | 2025 |
| Jaggi AS | | 2022 |
| JAH7 Invest AS | Financial services | 2018 |
| Jahera Invest AS | Wholesale & retail | 2023 |
| Jakk Eiendom AS | Real estate | 1999 |
| Jalla Jalla AS | Administrative & support | 2019 |
| Jalø AS | | 2022 |
| Jamo Property AS | Real estate | 2021 |
| Jams Invest AS | Real estate | 2019 |
| Jan Erik Aas AS | Construction | 2016 |
| Jan Sangvik Service Og Invest AS | | 2025 |
| Janho AS | | 2007 |
| Janne Mesel Holding AS | Real estate | 2018 |
| Janse Kommunikasjon AS | Professional & scientific | 2005 |
| Janssons Elektro Aktiebolag Nuf | Construction | 2009 |
| Janus Invest AS | | 2002 |
| Jarle Børrestad AS | Real estate | 2015 |
| Jarlsby Invest AS | Real estate | 2006 |
| Jasmine AS | Hospitality | 2023 |
| Jass Investering AS | Real estate | 2005 |
| Jatbygg AS | Professional & scientific | 2018 |
| Jatomi AS | Real estate | 2017 |
| Jatumark AS | Financial services | 2004 |
| Javel Oslo AS | Hospitality | 2022 |
| Jaz AS | Wholesale & retail | 2016 |
| JB Reme AS | Real estate | 2005 |
| Jb-Design AS | Professional & scientific | 2014 |
| Jbkri Invest AS | | 2019 |
| Jbmp AS | Information & communication | 2022 |
| JBS Eiendom AS | Real estate | 2012 |
| Jcc-Holding AS | | 2023 |
| Jealt Invest AS | Real estate | 2017 |
| Jedi Eiendom AS | Real estate | 2005 |
| Jegersberg Barnehagedrift AS | Education | 2012 |
| Jekas Invest AS | | 2019 |
| Jekmo AS | Real estate | 2014 |
| Jekyll Holding AS | Real estate | 2012 |
| Jema Holding AS | Financial services | 2014 |
| Jengax AS | Information & communication | 2021 |
| Jengen Invest AS | Financial services | 2019 |
| Jengos Invest AS | Administrative & support | 2012 |
| Jenny AS | Hospitality | 2014 |