| Isola AS | Manufacturing | 1983 |
| Isola Holding AS | Manufacturing | 1968 |
| Istanbul Steakhouse Cafe Og Bar AS | Hospitality | 2017 |
| It-Firma AS | Information & communication | 2024 |
| Itb Holding AS | Water & waste | 2005 |
| Iveti Oppdrag AS | Administrative & support | 2024 |
| J Holmen Holding AS | | 2007 |
| J.E Thingstad AS | | 2021 |
| J.K Invest AS | Real estate | 2019 |
| Jaktfall AS | Wholesale & retail | 2010 |
| Jala Buss AS | Wholesale & retail | 2018 |
| Jala Eiendom AS | Real estate | 1988 |
| Jan's AS | Wholesale & retail | 2012 |
| Jansen, Thom AS | Other services | 2016 |
| Jato Holding AS | Financial services | 2005 |
| JC Joy Holding AS | | 2026 |
| Jehco Holding AS | | 2026 |
| Jensen Support AS | Administrative & support | 2024 |
| Jernbanegata 11B AS | Real estate | 2021 |
| Jernbanegata 12 AS | Real estate | 2006 |
| Jernbanegata 14 AS | Real estate | 2024 |
| Jernbanegata 15 AS | Real estate | 2016 |
| Jernverkstomta Utbygging AS | Real estate | 2019 |
| Jeta Concept AS | Other services | 2018 |
| JH Halvorsen Service AS | Transport & logistics | 2021 |
| Jil Eiendom AS | Real estate | 2011 |
| JK Energy AS | Wholesale & retail | 2025 |
| JNW Holding AS | Information & communication | 2019 |
| Joc Holding AS | Real estate | 2008 |
| Joey's Bygg Og Transport AS | Transport & logistics | 2021 |
| Johan Steenks AS | Wholesale & retail | 2005 |
| John Hagen AS | Wholesale & retail | 2015 |
| John Morgan Telemark AS | Wholesale & retail | 2012 |
| Jon Helge Helgerud Holding AS | Real estate | 2008 |
| Jonnys Interiør AS | Wholesale & retail | 1998 |
| Jons Dekk & Felg AS | Wholesale & retail | 2003 |
| Joo Invest AS | Financial services | 2017 |
| Jovo Invest AS | Financial services | 2005 |
| JS Bygg & Undervisning AS | Education | 2023 |
| JS Invest Holding AS | | 2026 |
| JS Property AS | Real estate | 2026 |
| JSP Holding AS | | 2026 |
| JTL Holding AS | Wholesale & retail | 2021 |
| Just Living AS | | 2022 |
| Jøllstein Holding AS | | 2024 |
| Jønholtdalen Garasjelag SA | Real estate | 2010 |
| K - Konsult Invest AS | Professional & scientific | 2004 |
| K Skogen AS | Wholesale & retail | 2016 |
| K- Konsult Eiendom AS | Real estate | 2014 |
| K-A Holding AS | | 2024 |
| K-Konsult Bensindrift AS | Wholesale & retail | 2007 |
| K.Kaalstad Invest AS | | 2023 |
| K/A Entreprenør AS | Construction | 2025 |
| Kaalstad Eiendom AS | Real estate | 2020 |
| Kaalstad Holding AS | Real estate | 2020 |
| Kaass Discovery AS | Professional & scientific | 2017 |
| Kaffe & Thespesialen AS | Wholesale & retail | 2000 |
| Kai Andersen Eiendom AS | Real estate | 1999 |
| Kaia Solutions AS | Energy | 2010 |
| Kaldstack AS | Information & communication | 2026 |
| Kalland Elkrafttjeneste AS | Professional & scientific | 2016 |
| Kallarberget Va AS | Water & waste | 2020 |
| Kamagra Eiendom AS | Real estate | 2001 |
| Kamagra Holding AS | Real estate | 2009 |
| Kammerherreløkka 1 AS | Real estate | 2026 |
| Karavoilin AS | Information & communication | 2021 |
| Kariolas Holding AS | | 2005 |
| Karjolen Pub AS | Hospitality | 2007 |
| Karjolen Pub Da | Hospitality | 1995 |
| Karlsen Rød Reklameservice Ans | Professional & scientific | 1989 |
| Katrina Kaye Da | Arts & recreation | 2012 |
| Katro Holding AS | | 2024 |
| KB Takst AS | Professional & scientific | 2015 |
| KC Invest AS | Real estate | 2019 |
| KCH Invest AS | Real estate | 2023 |
| Kdfe AS | Real estate | 2021 |
| Kdfi AS | Real estate | 2016 |
| Ke Båtservice AS | Manufacturing | 2024 |
| Kebab Grillen AS | Hospitality | 2021 |
| Keims Gård AS | Real estate | 2004 |
| Kelda Automation Technology AS | Professional & scientific | 2016 |
| Kelda Dynamics AS | Professional & scientific | 2013 |
| Kelda Kraft AS | Information & communication | 2022 |
| Kemaro AS | Construction | 2026 |
| Kenmar AS | Financial services | 2014 |
| Kenneth Jacobsen Holding AS | Real estate | 2011 |
| Kerli Holding AS | Wholesale & retail | 2007 |
| Kerli Polymers AS | Wholesale & retail | 2023 |
| Kevin HJ Holding AS | | 2023 |
| Khai Holding AS | Real estate | 2005 |
| Khang Invest AS | Construction | 2016 |
| Kilden Eiendom AS | Real estate | 2025 |
| Kim Arne Invest AS | Real estate | 2016 |
| Kirkebukta Utbygging AS | Real estate | 2020 |
| Kirketjernet Tomt AS | Real estate | 2023 |
| Kirketjernet Utvikling AS | Real estate | 2013 |
| Kjell Dahlsrud Vvs-Senter AS | Construction | 1986 |
| Kjelleveien 23 AS | Real estate | 2010 |
| Kjennskogen Drift AS | Mining & quarrying | 2018 |
| Kjølnes Kiosk Da | Wholesale & retail | 1990 |