| Treservice Froland AS | Froland | 2022 |
| Tresfjord Vevstove Ans | Tresfjord | 1998 |
| Treskalle AS | Sandnes | 2018 |
| Treskjærerverkstedet AS | Lalm | 2015 |
| Tresleden AS | Verdal | 2024 |
| Trestokken Snekkerverksted AS | Kvinesdal | 2012 |
| Trestubben AS | Sand | 1995 |
| Tresystem AS | Koppang | 2015 |
| Tretec Byggsystemer AS | Stavanger | 2022 |
| Tretema AS | Nessane | 2001 |
| Trettemo Holding AS | Algarheim | 2012 |
| Trettemo Verksteddrift AS | Algarheim | 2012 |
| Treungen Sveis Og Service AS | Treungen | 2022 |
| Trevaren Eydehavn AS | Eydehavn | 2002 |
| Trevel AS | Nesøya | 2012 |
| Treverkstedet AS | Oslo | 1991 |
| Trevig AS | Klepp Stasjon | 2015 |
| Trevirkelaget Snekkeri AS | Buvika | 2022 |
| Trevita AS | Måløy | 2014 |
| Trewil AS | Kristiansund N | 2013 |
| Trez Grafisk AS | Oslo | 2001 |
| Triconor Norge AS | Oslo | 1980 |
| Trieye AS | Klokkarstua | 2017 |
| Trikag AS | Oslo | 2009 |
| Trimatic AS | Kleppe | 2020 |
| Trine Hundeartikler AS | Torp | 2005 |
| Tringa AS | Henningsvær | 1998 |
| Trinity Maritime Services Eood | Bg 9010 Varna | 2021 |
| Trinn Tre AS | Jevnaker | 2003 |
| Trio Dataservice AS | Stange | 1995 |
| Trio Food Processing Machinery AS | Stavanger | 1997 |
| Trio Treindustri Ans | Vistdal | 1999 |
| Triple-Energy AS | Kongshavn | 2008 |
| Triplenine Vedde AS | Langevåg | 1991 |
| Trippel H Holding AS | Eiken | 2018 |
| Triton Project Support AS | Kleppestø | 2009 |
| Trivest AS | Ågotnes | 2021 |
| Triway AS | Sandnessjøen | 2008 |
| Trobe AS | Ål | 2021 |
| Trofors Bil Og Landbruksverksted AS | Trofors | 2009 |
| Trofors Byggemontering AS | Trofors | 2020 |
| Trojan Norway AS | Bodø | 2015 |
| Troldmyr Møbelfabrikk AS | Eidsvåg I Romsdal | 1989 |
| Troll Elementer AS | Larvik | 2024 |
| Troll Salmon AS | Vestby | 1987 |
| Troll Systems AS | Bodø | 2015 |
| Trollblokk AS | Sandnes | 2016 |
| Trollbryggeriet AS | Liabygda | 2011 |
| Trollbua Eggedal AS | Eggedal | 2013 |
| Trollcard AS | Ski | 2010 |
| Trollfugl Holding AS | Vinterbro | 2023 |
| Trollheim Eiendom AS | Levanger | 2006 |
| Trollholmen AS | Lakselv | 2021 |
| Trolltunga Lille Bakeri AS | Odda | 2001 |
| Tromek Produksjon AS | Trondheim | 2016 |
| Tromek Service AS | Trondheim | 2016 |
| Trommedalsjordet Vest Eiendom AS | Skien | 2016 |
| Troms Maskin Og Service AS | Tromsdalen | 2021 |
| Tromsø Bakeri AS | Tromsø | 2000 |
| Tromsø Fiskeindustri AS | Tromsø | 2009 |
| Tromsø Fiskemat AS | Krokelvdalen | 1991 |
| Tromsø Marine Service AS | Tromsø | 2006 |
| Tromsø Mekaniske AS | Tromsø | 2001 |
| Tromsø Mikrobryggeri AS | Tromsø | 2015 |
| Tromsø Motor & Diagnoseservice AS | Tromsø | 2017 |
| Tromsø Motorservice AS | Tomasjord | 2008 |
| Tromsø Møbelstopp AS | Tromsø | 2020 |
| Tromsø Skipsservice AS | Tromsø | 2023 |
| Tromsø Stålindustri AS | Tomasjord | 1978 |
| Tromsø Tannteknikk AS | Tromsø | 1994 |
| Trond Egeland Holding AS | Sandnes | 2008 |
| Trond Geir Invest AS | Sortland | 2010 |
| Trond Haugvaldstad AS | Mosterøy | 2021 |
| Trond Helland Holding AS | Tysnes | 2024 |
| Trondheim Alu Og Eloksering AS | Heimdal | 2018 |
| Trondheim Estate AS | Trondheim | 1998 |
| Trondheim Gravmonumenter AS | Bosberg | 1995 |
| Trondheim Holding AS | Sandnes | 2025 |
| Trondheim Maskinverksted AS | Charlottenlund | 2022 |
| Trondheim Slaktehus AS | Trondheim | 2015 |
| Trondheim Steinindustri AS | Melhus | 1997 |
| Trondheim Stål AS | Melhus | 1989 |
| Trondheim Tek AS | Trondheim | 2023 |
| Trondsen Maskin & Sveiseteknikk AS | Bodø | 2012 |
| Tronrud Engineering AS | Hønefoss | 1989 |
| Tronrud Engineering Moss AS | Moss | 1987 |
| Trontek AS | Trondheim | 1986 |
| Trontveit Gard AS | Treungen | 2025 |
| Trosterud Holding AS | Oslo | 2013 |
| Trosterud Mekaniske Verksted AS | Vestby | 1983 |
| Trostrud - Freno AS | Lena | 1980 |
| Trosvik AS | Brevik | 2012 |
| Trosvik Yard AS | Brevik | 2020 |
| Trotan AS | Trondheim | 2016 |
| Trox Auranor AS | Jaren | 1996 |
| TRS B.V. | 1921Cx Akersloot | 2024 |
| Tru På Tre AS | Øystese | 2014 |
| Truck & Marine Service AS | Stathelle | 2007 |
| Truck & Service AS | Mosby | 1981 |
| Truck & Trailer Service AS | Oslo | 2018 |