| Institutt for Funksjonell Psykoterapi AS | Real estate | 1994 |
| Institutt for Handelsanalyser AS | Professional & scientific | 1992 |
| Institutt for Helhetsmedisin AS | Education | 2004 |
| Institutt for Holistisk Medisin & Meditasjon AS | Education | 2023 |
| Institutt for Holistisk Medisin Og Meditasjon | Health & social care | 2001 |
| Institutt for Musikerhelse Og Bevegelse AS | Education | 2020 |
| Institutt for Psykologisk Rådgivning Oslo AS | Health & social care | 2017 |
| Instrive Investment AS | | 2021 |
| Instrumentcompaniet AS | Wholesale & retail | 1998 |
| Instrumentservice AS | Other services | 2001 |
| Insulaee Holding Limited | | 2025 |
| Insulife AS | Manufacturing | 2020 |
| Insuran Group AS | | 2018 |
| Insurance Holding AS | Financial services | 2016 |
| Insurance Invest AS | | 2024 |
| Insurance Management Administration & Advisors AS | Financial services | 2006 |
| INT2ACT AS | Professional & scientific | 2025 |
| Intamin Transportation Ltd | Construction | 2005 |
| Intec Norge Øst AS | Professional & scientific | 2021 |
| Inteco AS | Professional & scientific | 2016 |
| Intecture Consulting AS | Professional & scientific | 2014 |
| Intego Digital AS | Professional & scientific | 2019 |
| INTEGR8 Fuels Oslo AS | Wholesale & retail | 2010 |
| Integra International AS | Professional & scientific | 2013 |
| Integra Invest AS | Professional & scientific | 2015 |
| Integra Sikkerhet AS | Administrative & support | 2022 |
| Integral Ad Science Norway AS | Professional & scientific | 2022 |
| Integral Consulting AS | Information & communication | 2022 |
| Integral Da | Information & communication | 2000 |
| Integral Health Star Method Holding Limited | | 2021 |
| Integral Health Star Method Limited | Health & social care | 2021 |
| Integral Manco AS | | 2025 |
| Integrated Cooperative Solutions AS | Wholesale & retail | 2006 |
| Integrated Detector Electronics AS | Professional & scientific | 1992 |
| Integrated Network Systems AS | Information & communication | 1993 |
| Integrated Wind Solutions ASA | Energy | 2020 |
| Integration Diagnostics Sweden AB | Professional & scientific | 2022 |
| Integritech AS | Information & communication | 2018 |
| Integritet Film AS | Information & communication | 2000 |
| Integumentum AS | Health & social care | 2022 |
| Integumentum Commune AS | Wholesale & retail | 2022 |
| Intel Analytics AS | Information & communication | 2025 |
| Intelco AS | Real estate | 2005 |
| Intele AS | Information & communication | 2004 |
| Intelecy AS | Information & communication | 2017 |
| Intellectsoft Norge AS | Information & communication | 2014 |
| Intellectual Capital Group AS | Real estate | 2000 |
| Intellectual Labs Holding AS | Professional & scientific | 2024 |
| Intelli Energi AS | Professional & scientific | 2024 |
| Intellident AS | Health & social care | 2011 |
| Intelligence Tradecraft AS | Education | 2017 |
| Intelligent Agent AS | Professional & scientific | 2009 |
| Intelligent Capital AS | Real estate | 2013 |
| Intelligent Data-Driven Solutions AS | Information & communication | 2025 |
| Intelligent Telecom Services AS | Information & communication | 1999 |
| Intelligent Trading AS | Financial services | 2018 |
| Intelligent Trading Holding AS | | 2018 |
| Intelligizer AS | Information & communication | 2018 |
| Intellika AS | Administrative & support | 2005 |
| Intellis AS | Information & communication | 2026 |
| Intellisec AS | Information & communication | 2016 |
| Intellitech AS | Information & communication | 2016 |
| Intellity AS | Wholesale & retail | 2018 |
| Intello Group AS | Information & communication | 2019 |
| Intense Capital AS | Financial services | 2026 |
| Intense Fund I AS | Financial services | 2026 |
| Intense Productions AS | Administrative & support | 2019 |
| Intento AS | Health & social care | 1989 |
| Intep AS | Construction | 1996 |
| Inter Alia AS | Financial services | 1993 |
| Inter Marked AS | Wholesale & retail | 2017 |
| Inter Pares AS | Real estate | 2005 |
| Inter Pro Data AS | Information & communication | 2012 |
| Inter Revisjon Norge AS | Professional & scientific | 2015 |
| Inter Tax AS | Professional & scientific | 1989 |
| Inter Travel Sport & Event AS | Administrative & support | 2009 |
| Inter-Consulting Europe (UK) Ltd | Information & communication | 2007 |
| Inter-Supply AS | Wholesale & retail | 1970 |
| Inter-Training AS | Education | 1984 |
| Interactive Software AS | Information & communication | 1995 |
| Interago AS | Information & communication | 2014 |
| Interago Holding AS | Information & communication | 2024 |
| Interaktiv Gruppen Ans | | 1992 |
| Interbe AS | Information & communication | 2022 |
| Interbrands Norway AS | Wholesale & retail | 1996 |
| Interbrands Spirits Norway AS | Wholesale & retail | 1978 |
| Interbridge AS | Education | 2015 |
| Interbygg Montering AS | Construction | 2015 |
| Interco Trading Ans | | 1990 |
| Intercom AS | Real estate | 2005 |
| Intercon AS | Professional & scientific | 1993 |
| Interconsult AS | | 2025 |
| Interconsult Medical AS | Health & social care | 2025 |
| Interesse AS | Professional & scientific | 2017 |
| Interest AS | Financial services | 1958 |
| Interestia AS | Information & communication | 2000 |
| Interface AS | Professional & scientific | 1996 |
| Interface Media AS | Manufacturing | 2003 |
| Interface Norge AS | Wholesale & retail | 1969 |
| Interference AS | Education | 2023 |