| Terra Nova X AS | | 2023 |
| Terrakontakt AS | | 2025 |
| Terrapeut AS | Professional & scientific | 1984 |
| Terravia Da | Arts & recreation | 2025 |
| Terskel AS | Information & communication | 2024 |
| Tesdal Holding AS | Information & communication | 2008 |
| Tesma AS | Real estate | 2005 |
| Tespa Holding AS | Financial services | 2016 |
| Tessemsvei 2 AS | Real estate | 1987 |
| Tessera AS | Information & communication | 2026 |
| Tesso AS | | 2025 |
| Test Holding AS | | 2023 |
| Tettpå! Bemanning AS | Administrative & support | 2007 |
| Tex AS | Wholesale & retail | 2005 |
| Texi AS | Information & communication | 2001 |
| Texicon AS | Information & communication | 2024 |
| Texmo AS | | 2025 |
| Teå Holding AS | | 2014 |
| TF Boligutvikling AS | Real estate | 2015 |
| TF Kompetanse AS | Education | 1992 |
| Tf-Invest AS | Financial services | 2007 |
| TFB Holding AS | | 2022 |
| TFK Produkter AS | Wholesale & retail | 2015 |
| Tge Bygg AS | Real estate | 2004 |
| TGH Holdings AS | Administrative & support | 2000 |
| TGM AS | Financial services | 2012 |
| Tgma Holding AS | | 2025 |
| TH Falkanger AS | Wholesale & retail | 1964 |
| Thai Kjøkken AS | Hospitality | 2012 |
| Thai Klinikk AS | Other services | 2017 |
| Thai Thai Trondheim AS | Hospitality | 2014 |
| Thaithai Trondheim Torg AS | Hospitality | 2017 |
| Thaulowgården AS | Real estate | 2005 |
| Thawornrit Invest AS | | 2026 |
| The Airborne Highfives Da | Arts & recreation | 2013 |
| The Directory/ AS | Wholesale & retail | 2026 |
| The Eye AS | Professional & scientific | 2023 |
| The Golden Leaves Band Da | Arts & recreation | 2023 |
| The Hair Clinic Trondheim AS | Health & social care | 2018 |
| The Hype AS | | 2024 |
| The Impossible Green Da | Arts & recreation | 2023 |
| The Kop Invest AS | Wholesale & retail | 2005 |
| The Leader AS | Other services | 2024 |
| The Life Balance Company AS | Information & communication | 2022 |
| The Norwegian Combat Academy AS | Education | 2024 |
| The Pro Bygg AS | Construction | 2016 |
| The Pro Drift AS | Administrative & support | 2024 |
| The Skin Clinic Norway AS | Health & social care | 2016 |
| The Skin Clinic Trondheim AS | Health & social care | 2016 |
| Thea Meinert Kunst AS | Arts & recreation | 2024 |
| Theia Invest AS | Real estate | 2025 |
| Theisendammen AS | Professional & scientific | 2025 |
| Thelma & Jomar Holding AS | | 2026 |
| Thelma Biotel AS | Information & communication | 2008 |
| Thelma Inneklima & Arbeidsmiljø AS | Professional & scientific | 2014 |
| Theoharis Holding AS | | 2024 |
| Thermadog AS | Wholesale & retail | 2026 |
| Thermophys AS | Professional & scientific | 2024 |
| Thevenin Data AS | Wholesale & retail | 1992 |
| Thevenin Eiendom AS | Real estate | 2000 |
| THF Invest AS | | 2021 |
| THG Holding AS | Professional & scientific | 2019 |
| Thgr Holding AS | | 2025 |
| This Is Juke AS | Administrative & support | 2024 |
| THM AS | Real estate | 2020 |
| Thme Holding AS | | 2020 |
| Thobias Knudsen Holding AS | Information & communication | 2026 |
| Tholok Invest AS | | 2022 |
| Thoma AS | Real estate | 1973 |
| Thoma Bolig AS | Real estate | 2007 |
| Thoma Prosjekt AS | Real estate | 2016 |
| Thoma Utvikling AS | Real estate | 2022 |
| Thomas Angells Gate 1 AS | Real estate | 2019 |
| Thomas Angells Gate 12 AS | Real estate | 2019 |
| Thomas Angells GT 3 AS | Real estate | 1995 |
| Thomas Angellsgt. 13 AS | Real estate | 1986 |
| Thomas AS | Financial services | 1973 |
| Thomas Hirsch GT 11 AS | Households | 1950 |
| Thomas J Borgan AS | Hospitality | 2024 |
| Thomas Myhre Holding AS | | 2025 |
| Thomas Nesser Holding AS | | 2025 |
| Thomas Nilsen Holding AS | Financial services | 2005 |
| Thomona Invest AS | | 2023 |
| Thon AS | Real estate | 2010 |
| Thor Bech Hansen Transport AS | Transport & logistics | 1996 |
| Thor Capital AS | Construction | 2019 |
| Thoragården Næring AS | Real estate | 2010 |
| Thoresen Partner AS | Professional & scientific | 2017 |
| Thorland Capital Management AS | | 2024 |
| Thorod Invest AS | Professional & scientific | 2019 |
| Thorsdag AS | Wholesale & retail | 2008 |
| Thorset Holding AS | | 2024 |
| Thorsø Capital AS | | 2026 |
| THR AS | | 2024 |
| Thrana Øyeklinikk AS | Health & social care | 2025 |
| Three Generations Da | Arts & recreation | 2026 |
| Three Lions Pub AS | Hospitality | 2005 |
| Thronæs-Takservice AS | Construction | 2024 |
| Thruster AS | | 2022 |
| THS Investment Group AS | Financial services | 2016 |