| Jakob Opdal AS | Construction | 1999 |
| Jakobsen Geoconsult AS | Professional & scientific | 2026 |
| Jakobsen Norman Holding AS | Construction | 2025 |
| Jakobsli Group AS | | 2021 |
| Jakobslivegen 1 AS | Real estate | 2017 |
| Jakobslivegen 65 AS | Real estate | 2017 |
| Jakobslivegen 7 Eiendom AS | Real estate | 2018 |
| Jaly Holding AS | | 2022 |
| Jamarka Invest Da | Financial services | 2009 |
| James AS | Hospitality | 2018 |
| Jameson Holding AS | | 2026 |
| Jan & Hans Trading Da | Wholesale & retail | 2003 |
| Jan Anders Syltern Invest AS | | 2020 |
| Jan Arve Service AS | Manufacturing | 2023 |
| Jan De Nul NV | Construction | 2010 |
| Jan Henrik Dahl Holding AS | Professional & scientific | 2020 |
| Jan Inge Solem Holding AS | | 2020 |
| Jan Magne Førde AS | Arts & recreation | 1990 |
| Jan Melvold Holding AS | Real estate | 2015 |
| Jan P Holding AS | Real estate | 2008 |
| Jan Schanke Frisørsalong AS | Other services | 1974 |
| Jan Syltern Invest AS | | 2005 |
| Jan Ulvan AS | Real estate | 1982 |
| Jani Engros AS | Wholesale & retail | 2000 |
| Jani Holding AS | Wholesale & retail | 2005 |
| Jani Restaurantdrift AS | Hospitality | 2024 |
| Janicke Marita Syltern Invest AS | | 2020 |
| Janyberg AS | | 2026 |
| Jara Invest AS | Financial services | 2017 |
| Jarala AS | Mining & quarrying | 2005 |
| Jarl Eiendom AS | Real estate | 2021 |
| Jarle Bjørstad Agenturer AS | Wholesale & retail | 1998 |
| Jarle Skaanes Holding AS | Real estate | 2007 |
| Jarleveien 4 AS | Real estate | 2014 |
| Jarleveien 44 AS | Real estate | 2011 |
| Jarleviktor Holding AS | | 2022 |
| Jarlheim AS | Professional & scientific | 2008 |
| Jarlheimsletta AS | Real estate | 2017 |
| Jarlheimsletta Holding AS | Real estate | 2022 |
| Jarls AS | | 2023 |
| Jarlsborgveien 2 B AS | Real estate | 2010 |
| Jash AS | Real estate | 2023 |
| Jaspis AS | | 2026 |
| Jator AS | Real estate | 1997 |
| Jatro AS | Real estate | 2000 |
| Jayko AS | Financial services | 2015 |
| JB Gruppen AS | | 2026 |
| Jba Invest AS | Professional & scientific | 2014 |
| JBJ Holding AS | | 2020 |
| JBJ Sunde Eiendom AS | Real estate | 2016 |
| JBS Partners AS | Professional & scientific | 2025 |
| JC Fitness AS | Wholesale & retail | 2021 |
| Jcdahls AS | Hospitality | 2025 |
| Jcdahls Holding AS | Hospitality | 2025 |
| JCG Invest AS | | 2021 |
| JCH Holding AS | Real estate | 2011 |
| JCK Holding AS | | 2019 |
| JCK Invest AS | | 2023 |
| Jddinvest AS | | 2024 |
| JDT Invest AS | | 2025 |
| Je-Bo AS | | 2021 |
| Je. Dahl Holding AS | Financial services | 2005 |
| Jebeveien 15 AS | Real estate | 2024 |
| Jebs Da | Information & communication | 2011 |
| Jedi Bar AS | Hospitality | 2006 |
| Jefr Invest AS | Financial services | 2012 |
| Jegerbruden Holding AS | | 2025 |
| Jeha AS | Administrative & support | 1998 |
| Jeha Invest AS | Financial services | 2005 |
| Jehi AS | Professional & scientific | 2005 |
| Jeje AS | Hospitality | 2006 |
| Jelle Venture AS | Real estate | 2010 |
| Jemi Eiendom AS | Real estate | 2025 |
| Jenfa AS | | 2005 |
| Jens Hoff AS | Wholesale & retail | 2008 |
| Jensbu AS | | 2019 |
| Jensen Bil AS | Wholesale & retail | 2019 |
| Jensen Bil Holding AS | Wholesale & retail | 2019 |
| Jensen Snekker Og Tømrerservice AS | Construction | 2016 |
| Jensen TXT AS | Professional & scientific | 2024 |
| Jensenholding AS | | 2023 |
| Jenssen Capital AS | | 2018 |
| Jenssen Invest & Holding AS | Information & communication | 2016 |
| Jernbanegaten 17 Eiendom AS | Real estate | 2006 |
| Jerome & Brit Catering Ans | Hospitality | 2002 |
| Jervbekken Holding AS | Wholesale & retail | 2005 |
| Jespersen AS | Professional & scientific | 2018 |
| Jess Sande Holding AS | | 2023 |
| Jest Invest AS | Financial services | 2011 |
| Jeth Consulting AS | Professional & scientific | 2012 |
| JFF Holding AS | | 2024 |
| JFP Eiendom AS | Real estate | 2019 |
| JG Invest AS | | 2022 |
| JGS Consult AS | Professional & scientific | 2004 |
| JH Technical AS | | 2019 |
| Jhalvorsen AS | Professional & scientific | 2025 |
| JHK AS | Arts & recreation | 2017 |
| JHK Holding AS | Arts & recreation | 2017 |
| Jhkpom AS | | 2022 |
| JHL Holding AS | | 2019 |