| HT Holdingselskap AS | | 2023 |
| HTC Holding AS | | 2024 |
| Hubra AS | Information & communication | 2026 |
| Hulaas AS | Real estate | 2020 |
| Hus & Håndverkstjenester AS | Construction | 2007 |
| Hypatia AS | Education | 1994 |
| Hypatia Learning AS | Information & communication | 2017 |
| Hysj AS | Administrative & support | 2026 |
| Hést AS | Wholesale & retail | 2014 |
| Høytrykk & Vakumteknikk AS | Administrative & support | 2015 |
| Høyvak Eiendom AS | Real estate | 2015 |
| Høyvak Holding AS | Administrative & support | 2016 |
| Ibalanse Regnskap & Rådgivning AS | Professional & scientific | 2021 |
| Inno Invest AS | | 2019 |
| Integrert Byggrådgivning AS | Professional & scientific | 2006 |
| Integro Produkt & Prosjekt AS | Wholesale & retail | 2018 |
| Integrum AS | Professional & scientific | 2017 |
| International Creativity Workshop AS | Arts & recreation | 2016 |
| Investerings Aksjeselskapet Onega AS | Real estate | 2008 |
| Isasol AS | Wholesale & retail | 2014 |
| Isegran Drift AS | Real estate | 2016 |
| Isegran Fartøyvernsenter AS | Manufacturing | 2000 |
| Isegran Fasadeprodukter AS | Wholesale & retail | 1998 |
| J2 Invest AS | | 2019 |
| Jacobs T. Design AS | Professional & scientific | 2024 |
| Jacobs Tonset Holding AS | Construction | 2023 |
| Jacobsen Autoinvest AS | Wholesale & retail | 2026 |
| Jan Amundsen Båtservice AS | Manufacturing | 2025 |
| Japan Auto AS | Wholesale & retail | 2003 |
| Jasa Holding AS | | 2020 |
| JC Bygg AS | Construction | 2018 |
| JC Kapital AS | | 2026 |
| Jernbanegata 12. AS | Real estate | 2022 |
| Jesper Arntzen Holding AS | | 2020 |
| JHB Music Production AS | Education | 2008 |
| Jme Consult AS | Professional & scientific | 2013 |
| Jobemi AS | Financial services | 2014 |
| Johi AS | Transport & logistics | 2020 |
| Join International AS | Information & communication | 2018 |
| Jonas Becken AS | Health & social care | 2021 |
| Jonas Bendik Holding AS | | 2026 |
| Jordbærpikene Værste AS | Hospitality | 2024 |
| Jotne FMV Vest 1 AS | Real estate | 1997 |
| Jotne FMV Vest 2 AS | Real estate | 2023 |
| JP Consulting AS | Health & social care | 2026 |
| JPG Investeringscompagnie AS | Wholesale & retail | 2005 |
| Just-Larsen Holding AS | Financial services | 2018 |
| Justerini Eiendom Ans | Real estate | 1997 |
| Jøtul AS | Manufacturing | 2006 |
| Jøtul Stoves AS | | 2026 |
| K B L Armering Østfold Ans | Manufacturing | 1991 |
| K Jespersen AS | | 2023 |
| Kampsporthuset Fredrikstad AS | Arts & recreation | 2025 |
| Kanonkule Media AS | Information & communication | 2021 |
| Karl Willy Holding AS | Financial services | 2005 |
| Karlsen Møbler AS | Wholesale & retail | 2018 |
| Kaya & Co AS | Professional & scientific | 2021 |
| Kebab House Ski AS | Hospitality | 2012 |
| Kinabolle Fredrikstad AS | Hospitality | 2024 |
| Kjellvik Holding AS | Other services | 2014 |
| Kjelsrud AS | Professional & scientific | 2019 |
| Kjøttværste AS | Wholesale & retail | 2024 |
| KK. Bygg AS | Construction | 2026 |
| Knud Bryns Vei 15 AS | Real estate | 2018 |
| Knud Bryns Vei 9 AS | Real estate | 2018 |
| Knut Larsen Agenturer AS | Wholesale & retail | 2009 |
| Knut Larsen AS | Wholesale & retail | 1996 |
| Kom Igjen AS | Information & communication | 2022 |
| Kosten AS | | 2023 |
| Kran Holding AS | Professional & scientific | 2023 |
| Kreativ Puls AS | Professional & scientific | 2020 |
| Krima Invest AS | | 2022 |
| Krona Invest AS | Real estate | 2005 |
| Kråkeby Barnehage AS | Education | 2022 |
| Kråkerøy Bygg AS | Construction | 2016 |
| Kråkerøy Byggkompetanse AS | Construction | 2021 |
| Kråkerøy Eiendomsutvikling AS | Real estate | 2018 |
| Kråkerøy Entreprenør Og Eiendom AS | Construction | 2021 |
| Kråkerøy Film AS | Information & communication | 2026 |
| Kråkerøy Fysioterapi Da | Health & social care | 1972 |
| Kråkerøy Holding AS | Real estate | 2023 |
| Kråkerøy Legesenter AS | Health & social care | 2007 |
| Kråkerøy Tak AS | Construction | 2024 |
| Kråkerøy Trafikkskole AS | Education | 2012 |
| Kråkerøytannlegene AS | Health & social care | 2013 |
| Kråkerøyveien 65 AS | Real estate | 2023 |
| Kullberg AS | Health & social care | 2015 |
| Kåre Pettersen Holding AS | Financial services | 2005 |
| Langthon Maritime AS | Wholesale & retail | 2017 |
| Langøy Consult AS | Professional & scientific | 2012 |
| Larsen Glassmontering Ltd Nuf | Construction | 2008 |
| Lavprisvvs Da | Wholesale & retail | 2005 |
| Lca.No AS | Information & communication | 2016 |
| Lekia Fredrikstad AS | Wholesale & retail | 2024 |
| Lend Invest AS | Financial services | 2004 |
| Lene's Kake Og Kaffebar Nuf | Wholesale & retail | 2009 |
| Lenmar AS | | 2019 |
| Lervik Revisjon AS | Professional & scientific | 1994 |
| Liefting Arkitektur & Restaurering AS | Professional & scientific | 2012 |
| Lineage Norway Holdings 2 AS | Real estate | 2020 |