| Instituttet for Fremtidsforskning | 1364 København K | 2012 |
| Instructure Sweden AB Nuf | 103 25 Stockholm | 2015 |
| Instrument Commissioning Services AS | Haugesund | 1992 |
| Insu El Tech AS | Narvik | 2019 |
| Insub AS | Stavanger | 2009 |
| Insvivia Technologies AS | Hidrasund | 2014 |
| Int'L Association of Scientific, Technical and Medical Publishers (STM) | 2595Be Den Haag | 2022 |
| INT2ACT AS | Oslo | 2025 |
| Intact Sport AS | Drammen | 2019 |
| Intactor AS | Moss | 2015 |
| Intark AS | Drammen | 2014 |
| Intco Power AS | Trondheim | 2025 |
| Intcon AS | Strusshamn | 2023 |
| Intec Norge Øst AS | Oslo | 2021 |
| Intech AB | 652 23 Karlstad | 2012 |
| Intech AS | Sandvika | 2000 |
| Intechs AS | Grimstad | 2013 |
| Inteco AS | Oslo | 2016 |
| Intecture Consulting AS | Oslo | 2014 |
| Integ AS | Engelsviken | 2021 |
| Intego Digital AS | Oslo | 2019 |
| Intego GmbH | 91058 Erlangen | 2009 |
| Integra International AS | Oslo | 2013 |
| Integra Invest AS | Oslo | 2015 |
| Integra PM Gruppen AS | Høvik | 2026 |
| Integraf AS | Verdal | 2022 |
| Integral Ad Science Norway AS | Oslo | 2022 |
| Integral Business Development AS | Skedsmokorset | 2008 |
| Integral Eda AS | Stavanger | 2025 |
| Integralis AS | Tromsø | 2018 |
| Integrate Consulting AS | Sirevåg | 2020 |
| Integrated Community Development Initiative | Loddefjord | 2010 |
| Integrated Detector Electronics AS | Oslo | 1992 |
| Integrated Solar AS | Trondheim | 2008 |
| Integration Diagnostics Sweden AB | Oslo | 2022 |
| Integrert Byggrådgivning AS | Kråkerøy | 2006 |
| Integrity Heat AS | Bryne | 2024 |
| Integrity Offshore Resources Ltd | Aberdeenshire Ab42 3Pq Scotland | 2017 |
| Integrotek AS | Stavanger | 2022 |
| Integrum AS | Kråkerøy | 2017 |
| Intek AS | Sandefjord | 1988 |
| Intekto AS | Sørumsand | 2025 |
| Intel Invest AS | Randaberg | 1999 |
| Intel Sampling AS | Randaberg | 1987 |
| Intelegal AS | Morvik | 2016 |
| Intellectual Capital Serv Norw AS | Billingstad | 1998 |
| Intellectual Labs AS | Vettre | 2019 |
| Intellectual Labs Holding AS | Oslo | 2024 |
| Intellectus AS | Stjørdal | 2020 |
| Intelli AS | Hamar | 2012 |
| Intelli Energi AS | Oslo | 2024 |
| Intelli Services AS | Trollåsen | 2022 |
| Intelli Solutions AS | Drammen | 2022 |
| Intellia AS | Ås | 2024 |
| Intellicess AS | Stavanger | 2025 |
| Intelligate AS | Raufoss | 2017 |
| Intelligent Agent AS | Oslo | 2009 |
| Intelligent Energy Solutions AS | Stavanger | 2016 |
| Intelligent Mud Solutions AS | Stavanger | 2010 |
| Intelligent Well Controls Ltd | Aberdeen Ab12 4Yd | 2015 |
| Intelligunt AS | Kristiansand S | 2016 |
| Intellilift AS | Kristiansand S | 2016 |
| Intellimar Consulting AS | Gullaug | 2025 |
| Intellion AS | Stavanger | 2026 |
| Intellution AS | Vigrestad | 2022 |
| Intend AS | Asker | 2021 |
| Intenor AS | Sandnes | 2022 |
| Intensjonell Holding AS | Trondheim | 2024 |
| Intent AS | Trondheim | 2021 |
| Intentional Design AS | Nøtterøy | 2019 |
| Intentium AS | Larvik | 2007 |
| Inter Aqua Advance Iaa | Dk-8250 Egå | 2014 |
| Inter Konsult AS | Billingstad | 1997 |
| Inter Regnskap AS | Trondheim | 2006 |
| Inter Regnskap Og Data AS | Hamar | 2011 |
| Inter Revisjon Norge AS | Oslo | 2015 |
| Inter Revisor AS | Gjøvik | 2005 |
| Inter Tax AS | Oslo | 1989 |
| Inter-Data AS | Halden | 1969 |
| Inter-Data Trondheim AS | Heimdal | 1985 |
| Inter-N Invest AS | Ålesund | 1997 |
| Interact AS | Melhus | 2000 |
| Interactor AS | Billingstad | 2019 |
| Interaktiv Design AS | Kolbotn | 2013 |
| Interaktiv Markedsføring AS | Steinkjer | 2023 |
| Interbooking AS | Løten | 2015 |
| Intercon AS | Oslo | 1993 |
| Interconcept AS | Sande I Vestfold | 1988 |
| Intercultural Management Consulting AB | 10216 Stockholm | 2012 |
| Intercultural Settlement and Communication Da | Nesttun | 2012 |
| Interesse AS | Oslo | 2017 |
| Interface AS | Oslo | 1996 |
| Interface Engineering Solutions Limited | Gb - Ab15 7Up Aberdeenshire | 2013 |
| Interfinance AS | Drammen | 2014 |
| Intergest Norge AS | Vøyenenga | 2012 |
| Intergraph (UK) Limited | Asker | 2014 |
| Intergraph France | Asker | 2014 |
| Intergrid OY Nuf | Fi-00100 Helsinki | 2026 |
| Intergroup AS | Siggerud | 2013 |
| Interhaus AS | Lysaker | 1987 |