| Henriksen Rørleggerbedrift A/S | Construction | 1987 |
| Hådem Helse & Holdings AS | | 2025 |
| Håkon Gamles Gate 2 AS | Real estate | 1990 |
| Håkon Samnøy AS | Information & communication | 2020 |
| Håndverkergaten 1A AS | Real estate | 2007 |
| Hårbølger AS | Other services | 2023 |
| Høglund Holding AS | Mining & quarrying | 2005 |
| Høglund Power Solutions AS | Professional & scientific | 2008 |
| Høyjord Eiendom AS | Real estate | 2026 |
| Ibenholt AS | Real estate | 2006 |
| Ibh Holding AS | Real estate | 2020 |
| Ibze AS | Real estate | 2018 |
| Ice Nyrerød Da | Real estate | 2003 |
| Ichi Retail Norway AS | Wholesale & retail | 2010 |
| Icm Holding AS | Real estate | 2005 |
| Ida Dahl Holding AS | Education | 2021 |
| Ido House Nuf | Administrative & support | 2022 |
| Idrettsregnskap AS | Professional & scientific | 2016 |
| Ikke Et Hvilket Som Helst Holding AS | Wholesale & retail | 2020 |
| Ilebrekkeveien 44 AS | Real estate | 2025 |
| Imagex AS | Professional & scientific | 2019 |
| Imeo AS | Professional & scientific | 2025 |
| Immitec Norge AS | Wholesale & retail | 1990 |
| Impact Consulting AS | Professional & scientific | 2016 |
| Imt AS | Professional & scientific | 2017 |
| Imzh AS | | 2018 |
| In-Vesta Bygg AS | Construction | 2016 |
| In-Vesta Eiendom AS | Real estate | 2017 |
| Inak 3 AS | Financial services | 2013 |
| Independent Investor Nuf | Financial services | 2006 |
| Indima AS | Real estate | 2005 |
| Indonor Eiendom AS | | 2025 |
| Infra AS | Agriculture & fishing | 2013 |
| Infravelo AS | Wholesale & retail | 2018 |
| Ingeniørfirmaet Rekon Da | Professional & scientific | 1996 |
| Ingenkommerihågenfegis Holding AS | | 2026 |
| Inglis Invest AS | Real estate | 2005 |
| Inknor Da | Water & waste | 2001 |
| Inndalsveien 1B AS | Real estate | 2021 |
| Inneklimaeksperten AS | Wholesale & retail | 2004 |
| Innlagveien 2 AS | Real estate | 2015 |
| Innotech AS | Professional & scientific | 2017 |
| Innz Medical AS | Wholesale & retail | 2013 |
| Inr Norge AS | Wholesale & retail | 2008 |
| Inside Productions Da | Arts & recreation | 1999 |
| Inspect Elektro AS | Professional & scientific | 2020 |
| Inst AS | Wholesale & retail | 2018 |
| Instrumentmaker Gro Hinna AS | Wholesale & retail | 2012 |
| Instrumentpartner AS | Wholesale & retail | 2018 |
| Integrio AS | | 2026 |
| Intercode AS | Information & communication | 2018 |
| Interi AS | Wholesale & retail | 2021 |
| International Development Partners AS | Information & communication | 2005 |
| Invent Design AS | Manufacturing | 2015 |
| Invest & Konsulenttjenester Henning Heimtun AS | Real estate | 1996 |
| Invest Omp AS | Education | 2021 |
| Invest Tørring AS | | 2022 |
| Investoralliansen AS | | 2024 |
| Investoralliansen Holding AS | Professional & scientific | 2023 |
| Invvst AS | Professional & scientific | 2016 |
| Inwessel AS | Real estate | 2017 |
| Inwestern AS | Financial services | 2014 |
| Irellis AS | Wholesale & retail | 2024 |
| Isdamveien AS | Real estate | 2022 |
| Isprint AS | Real estate | 2021 |
| IT Brekketoppen AS | Real estate | 2005 |
| Italian Design AS | Wholesale & retail | 1998 |
| Itel AS | Construction | 2019 |
| Ivk AS | Professional & scientific | 2012 |
| Izmailova Holding AS | | 2024 |
| J. Was Byggservice AS | Construction | 2026 |
| J.Nordli Holding AS | | 2022 |
| J.W Holding AS | | 2025 |
| J2P Eiendom AS | Real estate | 2005 |
| Jabs Norway AS | Wholesale & retail | 2008 |
| Jaby Holding AS | Real estate | 2000 |
| Jagjot Mann AS | Wholesale & retail | 2024 |
| Jahre Holding AS | | 2020 |
| Jajja AS | | 2020 |
| Jaktslottet AS | Other services | 2020 |
| Jamo Trading Da | Wholesale & retail | 2002 |
| Jan-Tore Stien AS | Other services | 2014 |
| Jarlsberg Bygg AS | Construction | 2019 |
| Jarlsberg Legesenter AS | Health & social care | 2025 |
| Jarlsø Eiendom AS | Real estate | 1994 |
| Jarlsø Invest AS | Real estate | 2013 |
| Jarlsø Marina AS | Manufacturing | 1996 |
| Jarlsø Mathus AS | Wholesale & retail | 2011 |
| Jarlsø Stål AS | Professional & scientific | 2021 |
| JARLSØ50 AS | Hospitality | 2022 |
| Jarlsøveien 12 AS | Real estate | 2013 |
| Jasu Holding AS | Wholesale & retail | 2024 |
| Jean & Marthinsen AS | Professional & scientific | 2002 |
| Jens Petter Zetlitz AS | Construction | 2004 |
| JENS1 Motorsport AS | Arts & recreation | 2026 |
| Jernbanetorget 1 AS | Real estate | 2002 |
| Jethold AS | | 2018 |
| Jht-Holding AS | Information & communication | 2010 |
| Jie Group AS | Wholesale & retail | 2024 |
| JMR Eiendom Invest AS | Real estate | 2022 |