| Takst Team Trøndelag Da | Real estate | 1999 |
| Takst Union AS | Professional & scientific | 2017 |
| Takst-Forum Trøndelag AS | Real estate | 2022 |
| Taxitjeneste AS | Transport & logistics | 2018 |
| Te Be AS | Financial services | 2005 |
| Team Ada AS | Administrative & support | 2024 |
| Tegnspråkhjerte AS | Wholesale & retail | 2022 |
| Teigesen Savings AS | Professional & scientific | 2020 |
| Teknisk Trefelling Og Transport AS | Agriculture & fishing | 2018 |
| Teknisk Ventilasjon AS | Construction | 1998 |
| Teknobingo Heimdal AS | Arts & recreation | 2007 |
| Teknotomten 3 Holding AS | Real estate | 2017 |
| Teknotomten 3 Næring AS | Real estate | 2017 |
| Teknotomten 3 PK AS | Real estate | 2025 |
| Teknotomten Holding AS | Real estate | 2016 |
| Teknotomten PK AS | Real estate | 2025 |
| Tempeveien 41 AS | Real estate | 2012 |
| Tempeveien 43 AS | Real estate | 2002 |
| Tempeveien 45 AS | Real estate | 2012 |
| Tempo Transport AS | Transport & logistics | 2010 |
| Terminalen 1 B AS | Real estate | 2012 |
| Terminalen 10 AS | Real estate | 2023 |
| Terminalen 10 Holding AS | Real estate | 2023 |
| Terminalen 12-14 AS | Real estate | 2022 |
| Terminalen 4 AS | Real estate | 1989 |
| Terminalen 7 AS | Real estate | 2012 |
| Terminalen Drift AS | Wholesale & retail | 2019 |
| Terminalen Entreprenør AS | Construction | 2013 |
| Terminalen Heimdal Holding AS | Real estate | 2023 |
| Terminalen Rigg AS | Real estate | 2013 |
| Terra Transport AS | Administrative & support | 2011 |
| Tess Holding AS | Financial services | 2005 |
| Thermomax Trondheim AS | Transport & logistics | 2002 |
| Thio AS | Manufacturing | 1999 |
| Thrios Bygg AS | Construction | 2024 |
| Tiller Blomster Nye AS | Wholesale & retail | 2018 |
| Tiller Utbyggingsselskap AS | Real estate | 2012 |
| Tillerli Holding AS | Professional & scientific | 1993 |
| Tiur Invest AS | Real estate | 2010 |
| Tmp-Holding AS | | 2026 |
| TNT Music Limited Nuf | Arts & recreation | 2008 |
| Toan Invest AS | | 2021 |
| Tomroy Lagerutleie AS | Real estate | 2023 |
| Tor Osvald Lund AS | Wholesale & retail | 1994 |
| Tores Transport AS | Transport & logistics | 2015 |
| Torgardsvegen 18 AS | Real estate | 2022 |
| Torgård 2 AS | | 2007 |
| Torgård 2 Holding AS | | 2025 |
| Torgård 3 AS | Real estate | 2019 |
| Torgård 3 Holding AS | | 2025 |
| Torgård Tomt 4 AS | | 2025 |
| Torgård Tomt 5A AS | Real estate | 2026 |
| Tosam Management AS | Professional & scientific | 2019 |
| Total-Uteservice AS | Administrative & support | 2018 |
| Totalsystem Finans AS | Administrative & support | 2017 |
| TR Tech AS | Professional & scientific | 2026 |
| Treigil Holding AS | | 2026 |
| Trekanten Lierne Ans | Real estate | 2009 |
| Trepro AS | Construction | 2013 |
| Tresnes Eiendom Drivenesvåg AS | Financial services | 2016 |
| Troll Under Brua AS | | 2025 |
| Trolltindan Invest AS | Professional & scientific | 2022 |
| Trolltindan Økonomi AS | Professional & scientific | 2022 |
| Trondheim Alu Og Eloksering AS | Manufacturing | 2018 |
| Trondheim Bygg Og Bad AS | Construction | 2018 |
| Trondheim Engineering AS | Professional & scientific | 2014 |
| Trondheim Hestesenter AS | Education | 2017 |
| Trondheim Kobber & Blikkslager AS | Construction | 1989 |
| Trondheim Marine AS | Wholesale & retail | 2012 |
| Trondheim Mur Og Våtrom II AS | Construction | 2023 |
| Trondheim Naprapati AS | Health & social care | 2019 |
| Trondheim Renholdsverk AS | Water & waste | 2005 |
| Trondheim Salg Og Utleie AS | Wholesale & retail | 2015 |
| Trondheim Syd Eiendom AS | Real estate | 2006 |
| Trygg Eiendomsmegling AS | Real estate | 2015 |
| Trygg Tak AS | Construction | 2025 |
| Trøan VVS AS | Construction | 2025 |
| Trøndelag Betongtransport AS | Transport & logistics | 2021 |
| Trøndelag Boligtakst AS | Professional & scientific | 2023 |
| Trøndelag Lakkpleie Da | Other services | 2008 |
| Trøndelag Transport Nuf | Transport & logistics | 2023 |
| Trønderbetong AS | Manufacturing | 2017 |
| Trønderburet AS | Manufacturing | 1991 |
| Trønderkjøkken AS | Wholesale & retail | 1999 |
| Trøndertrappa AS | Construction | 2025 |
| Trøndervask AS | Administrative & support | 2011 |
| TSB Takst Skade & Bygg AS | Real estate | 2013 |
| TTF Andersen Holding AS | | 2025 |
| Tuttis Holding AS | | 2024 |
| TVL Holding AS | | 2025 |
| Tørset Holding AS | Real estate | 2015 |
| Tørset Trading AS | Wholesale & retail | 2015 |
| Ulstadløkkveien 8 AS | Real estate | 2014 |
| Unitec AS | Construction | 2025 |
| Univital AS | Wholesale & retail | 2016 |
| Urmakermester Arne Asklund AS | Wholesale & retail | 1987 |
| Ut Events AS | Administrative & support | 2018 |
| Uttian Utvikling AS | Real estate | 2006 |
| V Foss Holding AS | Construction | 2022 |
| Valtec AS | Construction | 2015 |