| Jde Holding AS | Real estate | 2021 |
| JDK Eiendom AS | Real estate | 2010 |
| Jederveien 25 AS | Real estate | 2021 |
| Jef Eiendom AS | Real estate | 1997 |
| Jeløy Apotek AS | Wholesale & retail | 2021 |
| Jeløy Auto AS | Wholesale & retail | 2025 |
| Jeløy Bygg AS | Construction | 1996 |
| Jeløy Bygg Og Eiendom AS | Real estate | 2014 |
| Jeløy Båthavn AS | Transport & logistics | 2014 |
| Jeløy Bær AS | Agriculture & fishing | 2022 |
| Jeløy Eiendom AS | Construction | 1997 |
| Jeløy Eiendomsutvikling AS | Real estate | 1999 |
| Jeløy Elektro AS | Construction | 2017 |
| Jeløy Fisk Og Vilt AS | Wholesale & retail | 2004 |
| Jeløy Frisørsenter AS | Other services | 2019 |
| Jeløy Frukt Og Grønt Da | Wholesale & retail | 1997 |
| Jeløy Fysioterapi Da | Health & social care | 2022 |
| Jeløy Kiropraktorklinikk AS | Health & social care | 2019 |
| Jeløy Regnskap AS | Professional & scientific | 2022 |
| Jeløy Skotøy & Reparasjonsverksted AS | Wholesale & retail | 1994 |
| Jeløy Sushi AS | Hospitality | 2019 |
| Jeløy Tak & Blikkenslagerverksted AS | Construction | 2024 |
| Jeløy Tannklinikk AS | Health & social care | 2017 |
| Jeløy Utvikling AS | Real estate | 2019 |
| Jeløy VVS AS | Construction | 2016 |
| Jeløyfisk AS | Wholesale & retail | 1995 |
| Jensen Herrød Holding AS | Real estate | 2021 |
| Jenssen Bertheussen Holding Ans | Hospitality | 1997 |
| Jepcon AS | Transport & logistics | 2007 |
| Jer Holding AS | Real estate | 2011 |
| Jesper Kristensen AS | Wholesale & retail | 2022 |
| Jet Invest AS | | 2023 |
| JG Group Norge AS | Wholesale & retail | 2004 |
| JK Jensen Holding AS | | 2026 |
| Jncp AS | Professional & scientific | 2022 |
| JND Nordic AS | Wholesale & retail | 2025 |
| Joa Invest AS | Real estate | 2005 |
| Jobe Eiendom AS | Real estate | 2019 |
| Joby AS | Transport & logistics | 2000 |
| Joby Hova AB | Transport & logistics | 1998 |
| Jogn AS | Professional & scientific | 2016 |
| Joh Syvertsen & Sønner AS | Real estate | 1930 |
| Johannsson Holding AS | | 2019 |
| Johansen Transport AS | Transport & logistics | 1998 |
| John Svedman Midtskogen AS | Other services | 2013 |
| Joki AS | Information & communication | 2015 |
| Joma Nilsen Holding AS | Financial services | 2017 |
| Jon Otterbeck AS | Information & communication | 1972 |
| Jona Brynildsrud & Døtre AS | Hospitality | 2023 |
| Jonam AS | Construction | 2014 |
| Jonas & Lars El & Montage AB | Construction | 2004 |
| Jono Invest AS | Construction | 2012 |
| Joppen Invest AS | | 2023 |
| Jordbærpikene Mosseporten AS | Hospitality | 2008 |
| Jordbærpikene Rygge AS | Hospitality | 2026 |
| Jordmor Eriksens Vei 12 AS | Real estate | 2016 |
| Josis Holding AS | Financial services | 2014 |
| Jotek AS | Manufacturing | 1995 |
| Jotimala AS | Professional & scientific | 2026 |
| JP Coolstay AS | Transport & logistics | 2024 |
| JPH Investment AS | | 2025 |
| JR Transport AS | Transport & logistics | 2020 |
| JRL Holding AS | Real estate | 2014 |
| Julebrusen AS | Wholesale & retail | 2018 |
| Julhan AS | | 2025 |
| Juli Holding AS | Financial services | 2004 |
| Jupi-X Holding AS | Education | 2022 |
| Just - Me AS | Professional & scientific | 2014 |
| Justsen Energiteknikk A/S Nuf | Wholesale & retail | 1996 |
| JVS AS | Professional & scientific | 2024 |
| Jwille Holding AS | | 2024 |
| Jersin AS | Real estate | 1977 |
| K & K Eiendom AS | Real estate | 2005 |
| K&A Transport AS | Transport & logistics | 2025 |
| K.J Frisør AS | Other services | 2022 |
| K5 Holding AS | Real estate | 2022 |
| Kabra Invest AS | Real estate | 2005 |
| Kafrima AS | | 2023 |
| Kalenderidis Invest AS | Real estate | 2010 |
| Kalibra Regnskap AS | Professional & scientific | 2020 |
| Kallumveien 16 AS | Real estate | 2009 |
| Kallumveien 28 AS | Real estate | 2005 |
| Kalnes Næringspark 7 AS | Real estate | 2024 |
| Kambo Bolig AS | Real estate | 2020 |
| Kambo Holding AS | | 2021 |
| Kambo Legesenter AS | Health & social care | 2001 |
| Kambo Marina AS | Arts & recreation | 1990 |
| Kambo Marina Eiendom AS | Real estate | 2020 |
| Kambo Marina Holding AS | Arts & recreation | 2020 |
| Kambo Næring AS | Real estate | 2020 |
| Kambo Seniorbolig AS | Real estate | 2021 |
| Kambo Treningssenter AS | Arts & recreation | 2020 |
| Kambobricks.No AS | Wholesale & retail | 2024 |
| Kambobukta Boligutvikling AS | Real estate | 2020 |
| Kambobukta Eiendom AS | Real estate | 2013 |
| Kameni AS | | 2018 |
| Kamilles Holding AS | Wholesale & retail | 2005 |
| Kampenesmosen Lager AS | Real estate | 2025 |
| Kanalen Brygge AS | Real estate | 2016 |
| Kanalen Eiendom Moss AS | Real estate | 2007 |