| Interak AS | Information & communication | 2011 |
| Intercon AS | Real estate | 1988 |
| Invitare AS | Real estate | 2009 |
| Iotix Systems AS | Information & communication | 2014 |
| Itventure AS | | 2021 |
| Ix Emperor AS | Professional & scientific | 2018 |
| Jan G. Holding AS | | 2021 |
| JB - 20 Invest AS | Health & social care | 2020 |
| JBC Invest AS | Financial services | 2013 |
| Jessa Holding AS | Real estate | 2005 |
| Jetson AS | Wholesale & retail | 2017 |
| JHF AS | | 2023 |
| Jo Bruun Holding AS | Real estate | 2014 |
| Jodfabrikken AS | Professional & scientific | 2015 |
| Joggevogner Norge AS | Wholesale & retail | 1998 |
| Jongdal AS | Real estate | 1995 |
| Jonny Skrivarhaug Holding AS | Real estate | 2008 |
| Jonson Consulting AS | Administrative & support | 1993 |
| Josefinevogt AS | Professional & scientific | 2022 |
| JRN Holding AS | | 2022 |
| Jubalica AS | Real estate | 2007 |
| Juheba Invest AS | Real estate | 2016 |
| Jumm Eiendom AS | Real estate | 1988 |
| Jumm Invest AS | Real estate | 2004 |
| Junico AS | Financial services | 2005 |
| Jørgengård Holding AS | | 2023 |
| Jørgensens Instrumentverksted AS | Manufacturing | 2015 |
| K17 Holding AS | Wholesale & retail | 2007 |
| K9 Invest AS | Real estate | 2006 |
| Kaatsu Fitness & Rehab AS | Health & social care | 2023 |
| Kahaga AS | Financial services | 2016 |
| Kaj AS | Transport & logistics | 2023 |
| Kamm Invest AS | | 2013 |
| Kanobi AS | Real estate | 1997 |
| Kapinor AS | Real estate | 2017 |
| Karsten Invest AS | Real estate | 2005 |
| Kbra Holding AS | | 2021 |
| Kbu Holding AS | Professional & scientific | 2016 |
| Kek Holding AS | Financial services | 2005 |
| KHH Consulting Nuf | Professional & scientific | 2006 |
| King Investments AS | | 2019 |
| Kingo Eiendom AS | | 2000 |
| Kire Invest AS | Real estate | 2014 |
| Kirkeveien 226 Ans | Professional & scientific | 2004 |
| Kirksæter Invest AS | Financial services | 2015 |
| Kirurg Kjetil Misje AS | Health & social care | 2005 |
| Kleco AS | | 2014 |
| Klim-Jas Holding AS | | 2025 |
| Klim-Jas Ventilasjon AS | Construction | 2026 |
| Klippene AS | Education | 2018 |
| Klpa AS | | 2022 |
| Kmir AS | Financial services | 2014 |
| KNB Eiendom AS | Real estate | 2011 |
| Knewy AS | | 2016 |
| Knus P Leadership AS | Professional & scientific | 2021 |
| Kompetanse-Invest AS | Professional & scientific | 1984 |
| Korall Holding AS | | 2023 |
| Korn Kapital AS | | 2021 |
| KR Investment Capital AS | Real estate | 2020 |
| Kracing AS | Professional & scientific | 2026 |
| Kranka AS | Financial services | 2008 |
| Kreativ Byggutvikling AS | Professional & scientific | 2016 |
| Kris AS | Wholesale & retail | 2001 |
| Kristina Aarvold Holding AS | Professional & scientific | 2018 |
| Krt-Holding AS | Professional & scientific | 2024 |
| Kuhle Opplevelser AS | Administrative & support | 2022 |
| Kvadrat Holding AS | Real estate | 2006 |
| Kvervel AS | Professional & scientific | 2016 |
| KWG Holding AS | Financial services | 2015 |
| L M Dahl Ingeniørfirma AS | Wholesale & retail | 1993 |
| L16 Seksjon 9 AS | Real estate | 2025 |
| Lab-Tech AS | Wholesale & retail | 2009 |
| Lacolle Holding AS | Financial services | 2017 |
| Lailas Agenturer Ans | Wholesale & retail | 1994 |
| Lamp Services AS | Professional & scientific | 2012 |
| Lars Erik Hoel & Co AS | Professional & scientific | 1993 |
| LDK Bygg AS | Construction | 2024 |
| Lelia AS | Professional & scientific | 2019 |
| Li-Li Holding AS | | 2019 |
| Lindberg Invest AS | | 2010 |
| Lindebergveien 34A AS | | 2022 |
| Lindholmen AS | | 2005 |
| Linksted AS | Construction | 2021 |
| Linnea Shipping AS | Transport & logistics | 1998 |
| Linord AS | Health & social care | 2026 |
| Lisa Rolèn AS | Real estate | 2019 |
| Liseapotekene Lillestrøm AS | Wholesale & retail | 2021 |
| Live Foyn Friis AS | Arts & recreation | 2009 |
| Live IT Hegstad AS | Real estate | 2015 |
| Loba Holding AS | | 2025 |
| Loge Resources AS | Mining & quarrying | 2005 |
| Loraax AS | | 2024 |
| Luca Wines AS | Wholesale & retail | 2026 |
| Lucus AS | Real estate | 2012 |
| Lupo AS | | 2025 |
| Lykkestua AS | Hospitality | 2026 |
| Lysium AS | Professional & scientific | 2025 |
| Løvenskiolds Terrasse AS | Construction | 2016 |
| Ma-Si AS | Professional & scientific | 2005 |
| Mack Bygg Prosess AS | Professional & scientific | 2005 |