| Inter Invest AS | Real estate | 1999 |
| Interimpartner AS | Professional & scientific | 2017 |
| Interiør & Design AS | Wholesale & retail | 2023 |
| Interiørforum AS | Professional & scientific | 2000 |
| Interiørhuset Larvik AS | Wholesale & retail | 2013 |
| Intuition Sync AS | Information & communication | 2026 |
| Invest 2 Reinvest AS | Real estate | 2013 |
| Isaksen Flis Og Våtrom AS | Construction | 2010 |
| Islann Trading AS | Wholesale & retail | 2014 |
| Isoklima AS | Construction | 2019 |
| Isola Solar AS | Wholesale & retail | 2020 |
| Isso AS | Professional & scientific | 2024 |
| It-Tek AS | Professional & scientific | 2003 |
| Itec AS | Wholesale & retail | 2016 |
| Itec Eiendom AS | Real estate | 2018 |
| Itec Holding AS | Real estate | 2013 |
| Itec Utleie AS | Administrative & support | 2022 |
| Ivekst AS | Health & social care | 1990 |
| Ivekst Kommune AS | Health & social care | 2023 |
| Iver Bugge Ans | Transport & logistics | 1906 |
| J & K Eiendom AS | Real estate | 2018 |
| J Skalleberg AS | | 2022 |
| J&C Kompani AS | Health & social care | 2023 |
| Ja Bolig AS | Real estate | 2020 |
| Jacco Holding AS | Real estate | 2021 |
| Jacknit AS | Wholesale & retail | 1994 |
| Jaerson Eiendom AS | Real estate | 1997 |
| Jaerson Holding AS | Real estate | 2005 |
| Jais Holding AS | | 2025 |
| Jama Losen AS | Hospitality | 2024 |
| Jan Bergan Rettshjelper AS | Professional & scientific | 2016 |
| Jango AS | Other services | 2024 |
| Jani-Gruppen Ans | Real estate | 1996 |
| Janis Skujins Transport AS | Transport & logistics | 2014 |
| Janne Kristin Aase Hansen AS | Health & social care | 2005 |
| Jappis Kebab & Pizza AS | Hospitality | 2021 |
| Jaran Nilsen Holding AS | | 2024 |
| Jath AS | | 2019 |
| Jazz Frisør AS | Other services | 1989 |
| JB Invest Holding AS | Financial services | 2005 |
| Jbiz AS | Information & communication | 2004 |
| Jegh Holding AS | | 2022 |
| Jei Invest AS | Wholesale & retail | 2005 |
| Jen Investment AS | Financial services | 2005 |
| Jens Bilvask AS | Other services | 2026 |
| Jensens Conditori AS | Manufacturing | 1999 |
| Jernbanegata 10 Larvik AS | Real estate | 2025 |
| Jernverket Utvikling AS | Real estate | 2018 |
| Jerpeveien 13 AS | Real estate | 2015 |
| JG Creative AS | Professional & scientific | 2024 |
| JGB Holding AS | Construction | 2024 |
| JGP Bygg AS | Construction | 2026 |
| JHS Construction AS | Manufacturing | 2007 |
| JHS Holding AS | Real estate | 2005 |
| Jiangsu AS | Hospitality | 2023 |
| JK Krognes AS | Professional & scientific | 2014 |
| Jktb Holding AS | | 2024 |
| Jlhorst AS | Arts & recreation | 2019 |
| Jloj Holding AS | | 2026 |
| JNM AS | | 2025 |
| Jo-El Holding AS | Wholesale & retail | 2019 |
| Joakim Magnussen Holding AS | Wholesale & retail | 2005 |
| JOB4U.NO AS | Administrative & support | 2016 |
| Jobcar AS | Wholesale & retail | 1997 |
| Johansson Invest AS | Real estate | 2012 |
| Johnsen Transport AS | Transport & logistics | 1985 |
| Johs Kristiansen Eftf AS | Manufacturing | 1984 |
| Jonsson Bygg & Gård AS | Administrative & support | 2026 |
| Jonsul AS | Financial services | 2005 |
| Joska Invest AS | | 2006 |
| Jotron AS | Manufacturing | 1967 |
| JPB Invest AS | Professional & scientific | 2016 |
| JS Industry AS | | 2026 |
| Juno Larvik AS | Manufacturing | 1991 |
| JVD AS | | 2023 |
| JVG Holding AS | Wholesale & retail | 2018 |
| JVH Eiendom AS | Real estate | 2020 |
| JVH Eiendomsdrift AS | Real estate | 2021 |
| JVH Utvikling 01 AS | Real estate | 2024 |
| JVN Holding AS | Financial services | 2017 |
| Jø-Tek Ans | Transport & logistics | 1994 |
| Jønni Maskin AS | Professional & scientific | 1994 |
| Jørn Nordkvelde AS | Construction | 1998 |
| K a Enqvist Ans | Professional & scientific | 1986 |
| K Hurlen Invest AS | Real estate | 2017 |
| K K Import and Consulting Da | Wholesale & retail | 2003 |
| K Sandnes Eiendom AS | Real estate | 1976 |
| Ka Flessum AS | Real estate | 2020 |
| Ka Olsen Holding AS | | 2021 |
| Ka-Service AS | Professional & scientific | 2018 |
| Kaare Mortensen AS | Construction | 1990 |
| Kabelspesialistene AS | Construction | 2013 |
| Kaca AS | Wholesale & retail | 2007 |
| Kaffelykken AS | Wholesale & retail | 2024 |
| Kafé Hjørnet Larvik AS | Hospitality | 2026 |
| Kalstadsenteret AS | Real estate | 1992 |
| Kama Solutions Holding AS | Construction | 2024 |
| Kama Solutions Larvik AS | Construction | 2024 |
| Kamiline AS | Financial services | 2005 |
| Kanalgata 4/5 AS | Real estate | 1990 |