| Innomhus AS | Nesttun | 2003 |
| Innomotics GmbH Weiss Spindeltechnologie | De-96126 Maroldsweisach | 2026 |
| Innopro AS | Alta | 2011 |
| Innosafe AS | Roa | 2016 |
| Innotech EU GmbH | De-68307 Mannheim | 2024 |
| Innoterm | Dk-6000 Kolding | 2019 |
| Innoterm Nuf | 6000 Kolding | 2014 |
| Innova Bygg AS | Østerås | 1990 |
| Innovano AS | Risør | 2019 |
| Innovasjon Elektro AS | Bjørkelangen | 2015 |
| Innovasjonsbygg AS | Drøbak | 1986 |
| Innovatek AS | Glomfjord | 2013 |
| Innovation Spectrum Nuf | Lt-08457 Vilnius | 2023 |
| Innovatøren AS | Løken | 2024 |
| Innvær Mur & Betong AS | Nedre Vats | 2019 |
| Innvær Plast AS | Rubbestadneset | 1971 |
| Inoform AS | Sylling | 2023 |
| Inok AS | Oslo | 2012 |
| Inovativ Bygg AS | Mo I Rana | 2023 |
| Inoventio Geoteknikk AS | Langhus | 2017 |
| Inox Glass AS | Lommedalen | 2019 |
| Inp Bygg AS | Morvik | 2023 |
| Inpipe Bygg Og Rørfornyelse AS | Oslo | 2026 |
| Inpro Brunnsborrning AB | 22530 Sund | 2007 |
| Inredningsforum Byggentreprenad AB Nuf | Se-452 92 Strømstad | 2022 |
| Inselo Norge AS | Kristiansand S | 2015 |
| Inser AS | Stavanger | 2019 |
| Insert Glass Og Fasademontasje AS | Hølen | 2018 |
| Inserv AB | Se-364 33 Åseda | 2019 |
| Inspectify AS | Saltnes | 2022 |
| Inspira Maling AS | Oslo | 2026 |
| Inspiras AS | Ringebu | 2022 |
| Inspirations | Molde | 2007 |
| Inspo Bygg AS | Strømmen | 2024 |
| Insta Rør&Rehab AS | Vestby | 2023 |
| Instal Volt Jakub Ignatowicz Nuf | 63-210 Zerkow | 2025 |
| Instalatorstwo Sanitarne Co I Gaz Krzysztof Nowak | Langesund | 2006 |
| Install AS | Oslo | 2013 |
| Install Windows Maciej Przemielewsk | Pl-16-402 Sukalki | 2018 |
| Installasjon Og Salg AS | Tromsø | 1992 |
| Installasjons Partner AS | Råde | 2016 |
| Installasjonsbyrået Ingebrigtsen & Co Ans | Bardu | 1984 |
| Installasjonsfirmaet Owesen AS | Hvalstad | 1983 |
| Installasjonsservice AS | Løten | 1991 |
| Installationsgruppen AS | Oslo | 2022 |
| Installatør Bjørnar Eriksen AS | Sørstraumen | 2012 |
| Installatør Magne Ro AS | Tingvatn | 1998 |
| Installatør Olav Jordet AS | Torpo | 2010 |
| Installatør Ove E Thoresen AS | Drammen | 1992 |
| Installatør Per Øverland AS | Porsgrunn | 1971 |
| Installatør R Hansen AS | Breivikbotn | 2004 |
| Installatør Stig Lind AS | Myre | 1995 |
| Installatør Witzø AS | Tverlandet | 2011 |
| Installatøren Fredrikstad AS | Rolvsøy | 2013 |
| Installatøren Oslo AS | Oppegård | 2003 |
| Installatørene AS | Oslo | 2012 |
| Installatørservice AS | Nesttun | 1987 |
| Installere Elektro AS | Tromsø | 2022 |
| Instalsos AS | Trondheim | 2023 |
| Instant Service AS | Langhus | 2020 |
| Instant VVS AS | Skedsmokorset | 2016 |
| Instatak AS | Svelvik | 2025 |
| Instatech AS | Jessheim | 2021 |
| Instaworks AS | Vaksdal | 2023 |
| Instefjord Asfalt AS | Leikanger | 2006 |
| Instefjorden AS | Storebø | 2023 |
| Insula Energikompetanse AS | Hønefoss | 2018 |
| Insultech No | 3133Kg Vlaardingen | 2026 |
| Insuru AS | Tysværvåg | 2005 |
| Intamin Transportation Ltd | Oslo | 2005 |
| Intec GMK GmbH Nuf | De-18211 Ot Bargeshagen | 2024 |
| Integración Tecnológica Empresarial, S.L | Es-6 28670 Madrid | 2021 |
| Integral Bygg AS | Tromsdalen | 2018 |
| Intelliglass AS | Mjøndalen | 2026 |
| Intep AS | Oslo | 1996 |
| Inter Art AS | Viggja | 2025 |
| Inter Bygg AS | Rådal | 2022 |
| INTER MAJA Jan Malczewski | 42-200 Czestochowa | 2005 |
| Inter Moda AS | Skåla | 2020 |
| Inter Rør AS | Langevåg | 2023 |
| Inter-Bygg AS | Glesvær | 1987 |
| Inter-Mont Holding AS | Sande I Vestfold | 2005 |
| Inter-Tech Maskin AS | Oppdal | 2022 |
| Interactive AS | Drammen | 2003 |
| Interbygg Montering AS | Oslo | 2015 |
| Interbygg Nord AS | Bodø | 2020 |
| Intercontinental Modular Systems | Knarrevik | 2013 |
| Interflex Medizintechnik GmbH | Oslo | 2017 |
| Intergas AS | Risør | 2002 |
| Intergas Holding AS | Risør | 2005 |
| Interhall Spolka Z Organiczona Odpowiedzialnocia | Pl-40-144 Katowice | 2014 |
| Interiør & Malerfirma Tjelta Gulv Og Bad AS | Hauge I Dalane | 2023 |
| Interiør Consult Arendal AS | Kolbjørnsvik | 1994 |
| Interiør Ekspert AS | Oslo | 2020 |
| Interiør Og Budservice AS | Greåker | 2019 |
| Interiør Service Helgeland AS | Sandnessjøen | 2001 |
| Interiør-Snekkern AS | Barkåker | 2015 |
| Interiørfaghuset T. Lund AS | Stavanger | 2018 |
| Interiørgården AS | Sandnes | 2000 |
| Interiørmetall AS | Drammen | 1997 |