| T Ø Helgesen AS | | 2025 |
| T&K Gruppen AS | Professional & scientific | 2024 |
| T-B Holding AS | Other services | 2005 |
| T-E Holding AS | | 2025 |
| T-Finans AS | Transport & logistics | 2011 |
| T-H-O-M AS | Wholesale & retail | 2020 |
| T. a. Myhre Holding AS | | 2019 |
| T. Aa Holding AS | | 2020 |
| T. Larsen Invest AS | Administrative & support | 2019 |
| T.H Consulting AS | Professional & scientific | 2024 |
| T.I.V.A-Hjem AS | Real estate | 2023 |
| T.I.V.A. Holding AS | Wholesale & retail | 2022 |
| T.R.A.K AS | Financial services | 2005 |
| T.S.Jenssen Holding AS | Financial services | 2005 |
| T3 Eiendom AS | Real estate | 2003 |
| T3 Invest AS | Real estate | 2010 |
| T4LENT AS | Professional & scientific | 2018 |
| T8 Invest AS | Real estate | 2019 |
| Ta Tiden Tilbake AS | Information & communication | 2011 |
| Ta Utvikling AS | Professional & scientific | 2018 |
| Ta-Innsikt AS | Professional & scientific | 2025 |
| Tabarca AS | Real estate | 2020 |
| Tabazco Norup Fashion | Wholesale & retail | 1998 |
| Tacapella AS | Other services | 2024 |
| Tafe Holding AS | | 2023 |
| Taftøy Næringspark AS | Real estate | 2022 |
| Tag Management AS | Hospitality | 2014 |
| Tag Restaurant AS | Hospitality | 2015 |
| Taga Foods AS | Manufacturing | 2000 |
| Taga Holding AS | Real estate | 1997 |
| Taga Invest AS | Real estate | 2004 |
| Tagline AS | Information & communication | 2019 |
| Tags Eiendom AS | Real estate | 2026 |
| Tagwest Eiendom AS | Real estate | 2025 |
| Tailwind Invest AS | Real estate | 2006 |
| Tak Service Trondheim AS | Construction | 2024 |
| Takh Holding AS | Wholesale & retail | 2005 |
| Takk Holding AS | | 2026 |
| Takst Midt-Norge AS | Professional & scientific | 2023 |
| Taksthuset Trøndelag AS | | 2025 |
| Takstingeniør Sigurd Sivertsen AS | Professional & scientific | 2026 |
| Takt Bygg AS | Construction | 2017 |
| Takt Terapeutene AS | Health & social care | 2024 |
| Talberg & Aarvåg Bygg AS | Construction | 2026 |
| Taledrift AS | Information & communication | 2025 |
| Talent One AS | Professional & scientific | 2015 |
| Talera AS | Professional & scientific | 2020 |
| Talera Holding AS | Professional & scientific | 2021 |
| Talk to AS | Professional & scientific | 2000 |
| Talladega AS | | 2021 |
| Tally Iot AS | Wholesale & retail | 2021 |
| Talmo Invest AS | Professional & scientific | 2007 |
| Tan Holding AS | Information & communication | 2002 |
| Tandoori Flame AS | Hospitality | 2026 |
| Tandoorikjøkken AS | Hospitality | 2012 |
| Tanem Eiendom AS | Real estate | 1997 |
| Tangent 007 AS | Professional & scientific | 2022 |
| Tank Design Trondheim AS | Professional & scientific | 2017 |
| Tanngarden Trondheim AS | Health & social care | 2024 |
| Tannklinikken Dent AS | Health & social care | 2021 |
| Tannkraft AS | Health & social care | 2026 |
| Tannlege Ane Amdal AS | Health & social care | 2022 |
| Tannlege Arne-Henrik Finnanger AS | Health & social care | 2013 |
| Tannlege Eivind Skaar AS | Health & social care | 2023 |
| Tannlege Endre Winje AS | Health & social care | 2025 |
| Tannlege Eriksen AS | Health & social care | 2013 |
| Tannlege Eva Børstad AS | Health & social care | 2003 |
| Tannlege Gunnfrid Alrek AS | Health & social care | 1993 |
| Tannlege Hanne Bach AS | Health & social care | 2016 |
| Tannlege Ingunn Omestad Solberg AS | Health & social care | 2024 |
| Tannlege Ivar Morten Fagerholt AS | Health & social care | 2008 |
| Tannlege Johan Svensson AS | Health & social care | 2011 |
| Tannlege MSR AS | Health & social care | 2021 |
| Tannlege Ohm AS | Health & social care | 2020 |
| Tannlege Ola Strugstad Mørkved AS | Health & social care | 2026 |
| Tannlege Pål S. Kvinge AS | Health & social care | 2013 |
| Tannlege Randi Rian Five AS | Health & social care | 2005 |
| Tannlege Raymond De Freitas AS | Health & social care | 2000 |
| Tannlege Siri Ljøkjel AS | Health & social care | 2020 |
| Tannlege Terje Solheim Holding AS | Health & social care | 2022 |
| Tannpleier Trude Brekken Corneliussen AS | Health & social care | 2016 |
| Tannreg AS | Health & social care | 1989 |
| Tano Management Services AS | Professional & scientific | 2023 |
| Tapes of Relation AS | | 2026 |
| Tapper & Co Advokatfirma Ans | Professional & scientific | 1990 |
| Tapper & Co Advokatfirma Da | Professional & scientific | 2002 |
| Tapperietpaadahls AS | Administrative & support | 2016 |
| Taps AS | Wholesale & retail | 2017 |
| Taram AS | Wholesale & retail | 2007 |
| Taris AS | Wholesale & retail | 2022 |
| Tarje Skjefstad AS | Professional & scientific | 2012 |
| Tarto AS | | 2025 |
| Tas Holding AS | Financial services | 2005 |
| Tascon AS | Professional & scientific | 2014 |
| Tast Holding AS | | 2026 |
| Tasto Eiendom AS | Professional & scientific | 2026 |
| Tasty Trondheim AS | Hospitality | 2025 |
| Tatljpæng Investering AS | Information & communication | 2022 |
| Tatooine Holding AS | Financial services | 2016 |
| Tauro Properties AS | Real estate | 2008 |