| J.K Sundheim Holding AS | | 2022 |
| J.Lindeberg Norge AS | Wholesale & retail | 2012 |
| J.London Holding AS | Real estate | 2016 |
| J.Mo AS | | 2020 |
| J.O Eiendom AS | Real estate | 1997 |
| J.P. Morgan SE - Oslo Branch Nuf | Financial services | 2018 |
| J.P.C. Holding AS | Professional & scientific | 2021 |
| J.P.Wallet AS | | 2023 |
| J.R. Holding AS | Professional & scientific | 2023 |
| J.Ray Mcdermott (Norway), AS | Administrative & support | 2009 |
| J.S Sedal Invest AS | Real estate | 2010 |
| J.Sondov Holding AS | Financial services | 2016 |
| J.Sunde Invest AS | | 2019 |
| J.T. Birkeland Holding AS | Information & communication | 2020 |
| J12 Invest AS | Professional & scientific | 2018 |
| J19 Holding AS | Real estate | 2023 |
| J2 Kimchi AS | Wholesale & retail | 2026 |
| J2 Kimchi Holding AS | | 2026 |
| J2KOREANMART AS | Wholesale & retail | 2021 |
| J3M Norge AS | Construction | 2025 |
| J8 Ventures AS | | 2021 |
| Ja 281 Holding AS | | 2023 |
| Ja Botn Invest AS | | 2020 |
| Ja Consult AS | Professional & scientific | 1987 |
| Ja Design Ans | Professional & scientific | 1996 |
| Ja Hatlelid Holding AS | Information & communication | 2020 |
| Ja Industrier AS | Professional & scientific | 2017 |
| Ja Trafikkopplæring AS | Education | 2022 |
| Ja. Holding AS | | 2025 |
| JA2 Holding AS | | 2021 |
| Jaa AS | | 2018 |
| Jaa Invest AS | Real estate | 2020 |
| Jaaa AS | | 2020 |
| Jaaberg AS | Professional & scientific | 2015 |
| Jaae Invest AS | Real estate | 2015 |
| Jaanja AS | Financial services | 2002 |
| Jaas AS | Financial services | 2006 |
| Jaas Holding AS | Real estate | 2020 |
| Jaas Invest AS | | 2020 |
| Jaasund AS | Real estate | 2006 |
| Jab C Holding AS | Administrative & support | 2022 |
| Jab Invest AS | | 2018 |
| Jab Josef Anstoetz KG Nuf | Wholesale & retail | 1995 |
| Jaba Invest AS | Real estate | 2018 |
| Jabbar Invest AS | | 2025 |
| Jabbe Invest AS | | 2020 |
| Jabesk AS | Real estate | 2014 |
| Jablovski AS | Real estate | 2007 |
| Jabo Holding AS | Financial services | 2016 |
| Jabo Management & Consulting AS | Real estate | 2016 |
| Jaca Invest AS | Financial services | 2005 |
| Jacana Holding AS | Financial services | 2015 |
| Jacaranda Eiendom AS | Real estate | 2007 |
| Jaccos Beverage Group AS | Wholesale & retail | 2021 |
| Jacek Gubala | Construction | 2008 |
| Jack AS | Construction | 2022 |
| Jack-Of-All-Trades AS | Professional & scientific | 2008 |
| Jackbow Da | Information & communication | 2018 |
| Jackie AS | Wholesale & retail | 2012 |
| JACKK100 AS | Wholesale & retail | 2025 |
| Jaclie AS | Real estate | 1977 |
| Jaclie Eiendom AS | Real estate | 2024 |
| Jaco Holding AS | | 2020 |
| Jaco Invest AS | Transport & logistics | 1995 |
| Jacob a AS | | 2026 |
| Jacob Aall Parkeringshus AS | Real estate | 2004 |
| Jacob Aalls Gate 17 AS | Households | 1928 |
| Jacob Aalls Gate 27 Eiendom AS | Real estate | 2023 |
| Jacob Aallsgate 28 AS | Real estate | 2017 |
| Jacob Aallsgate 9 Invest AS | Real estate | 2011 |
| Jacob Bergsland Holding AS | Financial services | 2015 |
| Jacob Cafe & Restaurant AS | Hospitality | 1999 |
| Jacob Holding AS | | 2021 |
| Jacob Invest AS | Professional & scientific | 2005 |
| Jacob Johansen Holding AS | | 2025 |
| Jacob K. AS | Financial services | 2015 |
| Jacob Og Vo Ans | Hospitality | 2018 |
| Jacob's Auto Supply AS | Wholesale & retail | 2017 |
| Jacobs & Turner Ltd Nuf | Wholesale & retail | 2005 |
| Jacobs Eiendom AS | Real estate | 1934 |
| Jacobs Norge AS | Professional & scientific | 2024 |
| Jacobs Viine AS | Wholesale & retail | 2013 |
| Jacobsen Coaching AS | Education | 2019 |
| Jacobsen Dental AS | Wholesale & retail | 1968 |
| Jacobsen Gravferd AS | Other services | 1932 |
| Jacobsen Kapital AS | Professional & scientific | 2024 |
| Jacobsen's Eftf. AS | Wholesale & retail | 2003 |
| Jacon A/S | Professional & scientific | 1982 |
| Jaconsult AS | Administrative & support | 2022 |
| Jacquis AS | Real estate | 2006 |
| Jactosol Holding AS | Financial services | 2020 |
| Jada AS | Real estate | 2004 |
| Jada Invest AS | Professional & scientific | 2016 |
| Jadah Holding AS | | 2025 |
| Jadani AS | | 2021 |
| Jadda Holding AS | | 2024 |
| Jade Eiendom AS | Professional & scientific | 2006 |
| Jaeger AS | Hospitality | 2010 |
| Jaegerbombom AS | | 2022 |
| Jaegerbooking AS | Professional & scientific | 2014 |