| Tannlege Eirik Flodin AS | Health & social care | 2012 |
| Tannlege Frestad Andersen AS | Health & social care | 2024 |
| Tannlege Kai B Hannestad AS | Health & social care | 1994 |
| Tannlege Stine Cecilie Magnussen AS | Health & social care | 2020 |
| Tannlegene Grønstad AS | Health & social care | 2006 |
| Tapas I Drammen AS | Hospitality | 2024 |
| Tapas I Fredrikstad AS | Hospitality | 2022 |
| Taproom AS | Hospitality | 2017 |
| Tarkon AS | Wholesale & retail | 2025 |
| Tasty Panda AS | Hospitality | 2023 |
| Tatanka Bygg AS | Construction | 2020 |
| TB Eiendomsinvest AS | Real estate | 2006 |
| TB1 Eiendom AS | Real estate | 2019 |
| TBL AS | Wholesale & retail | 2025 |
| TC Lervik Services AS | Professional & scientific | 2024 |
| TDK Eiendom AS | Real estate | 2014 |
| TDK Invest AS | Professional & scientific | 2014 |
| TDK Media AS | Professional & scientific | 2004 |
| TDK Media Holding AS | Information & communication | 2018 |
| TDK Nett AS | Information & communication | 2012 |
| Team Antonsen Trafikkskole AS | Education | 2011 |
| Team Aonda Da | Construction | 2004 |
| Techweb Holding AS | Professional & scientific | 2021 |
| Teian Eiendom AS | Real estate | 2024 |
| Teian Holding AS | Real estate | 2024 |
| Teis AS | Agriculture & fishing | 2020 |
| Teli Invest AS | Professional & scientific | 2018 |
| Temareiser Fredrikstad AS | Administrative & support | 2018 |
| Terje Andersen Holding AS | Financial services | 2005 |
| Terje Høili AS | Real estate | 2012 |
| Terje Høili Eiendom AS | Real estate | 1998 |
| Terje Langaker AS | Wholesale & retail | 1978 |
| Terje Martinsen Holding AS | | 2019 |
| Terjos AS | Professional & scientific | 2025 |
| Terra Brux Solutions AS | Professional & scientific | 2025 |
| Tev Eiendom AS | Real estate | 2024 |
| Textilcompagniet Ans | Wholesale & retail | 1993 |
| TF Pizzaexpressen Marketing Norge AS | Hospitality | 1995 |
| Tgere AS | | 2020 |
| Tgholding AS | Professional & scientific | 2021 |
| TH Ove Rammsgate AS | Real estate | 2002 |
| TH Ove Rammsgate II AS | Financial services | 2013 |
| Thai Market AS | Hospitality | 2010 |
| Thaisann Market AS | Wholesale & retail | 2025 |
| The Great Escape AS | Arts & recreation | 2018 |
| The Paragon Group AS | | 2024 |
| The Paragon Group Holding AS | | 2024 |
| The Pitch AS | Professional & scientific | 2008 |
| Thella AS | | 2020 |
| Therese Hoff Dame & Herrefrisør AS | Other services | 2013 |
| Thermoprotection AS | Professional & scientific | 2009 |
| They See Me Holding AS | | 2026 |
| Thilde Holding AS | Information & communication | 2025 |
| Thinthan Fredrikstad AS | Hospitality | 2013 |
| Thomas Zakariassen Holding AS | Professional & scientific | 2023 |
| Thomassen R. AS | Manufacturing | 2025 |
| Thomassen R. Holding AS | | 2024 |
| Thor Andre Gretland Holding AS | | 2022 |
| Thorsen Montering AS | Construction | 2026 |
| Thorsen-Holding AS | Construction | 2021 |
| Thrift Group AS | Professional & scientific | 2016 |
| Thsz Invest AS | | 2022 |
| Thunes Invest AS | Real estate | 2017 |
| Ticonsult AS | Professional & scientific | 2026 |
| Tiden Eiendom AS | Real estate | 2016 |
| Tigern Invest AS | | 2020 |
| Til Fots AS | Administrative & support | 2019 |
| Tilpassetopplaering.No Da | Education | 2006 |
| Tim Investment AS | | 2021 |
| Tindra AS | Professional & scientific | 2017 |
| Tiramisu Café & Resturant AS | Hospitality | 2016 |
| TK Eiendomsselskap AS | Real estate | 2006 |
| Tla Retail AS | Wholesale & retail | 2025 |
| TLS Core AS | Wholesale & retail | 2014 |
| TLS Development AS | Real estate | 2017 |
| TLS Salgs Og Tilhengerutleie Da | Wholesale & retail | 2001 |
| TM Byggsystem AS | Construction | 2021 |
| TM Jensen Holding AS | Real estate | 2005 |
| TM Klinikken AS | Health & social care | 2014 |
| TM Legetjenester AS | Health & social care | 2025 |
| Tme Bygg AS | Construction | 2013 |
| To-Fag Nuf | Administrative & support | 2020 |
| Toboli Holding AS | | 2026 |
| Toeno Drift AS | Other services | 2026 |
| Tolk-En AS | Professional & scientific | 2018 |
| Tolketjeneste AS | Professional & scientific | 2025 |
| Tollefsen Grafiske AS | Manufacturing | 1995 |
| Tomteveien 19 Invest AS | Real estate | 1965 |
| Tomteveien 2-4-6 AS | Real estate | 2019 |
| Tomteveien 31 AS | Real estate | 2009 |
| Tool Depot AS | Wholesale & retail | 2011 |
| Tool Depot Norge AS | Wholesale & retail | 2026 |
| Topptind AS | Wholesale & retail | 2018 |
| Tor Erik Flateby AS | | 2018 |
| Torgautar AS | Professional & scientific | 2005 |
| Torgauten AS | Real estate | 2006 |
| Torgauten Asset Management AS | Administrative & support | 2023 |
| Torgauten Holding AS | Real estate | 2019 |
| Torgauten Næringseiendom AS | Real estate | 2024 |
| Torium Konsult AS | Construction | 2017 |