| Thomas Andre Eike AS | Wholesale & retail | 2023 |
| Thomassen Bygg & Eiendom AS | Construction | 2024 |
| Thomassen Eiendom & Konsulenttjenester AS | Real estate | 2019 |
| Thor Maritime AS | Professional & scientific | 2024 |
| Thor Steinar Byggtjenester AS | Construction | 1998 |
| Thoreas AS | Real estate | 2003 |
| Thoresens Marketing Ans | Wholesale & retail | 2003 |
| Thormodsen Holding AS | Wholesale & retail | 2005 |
| Thorstein Lund Holding AS | Construction | 2018 |
| Thorvig Invest AS | | 2025 |
| THREE60 Energy Norway AS | Mining & quarrying | 2011 |
| THS S Falck AS | Wholesale & retail | 1979 |
| THS. Falck Invest AS | Financial services | 2005 |
| Thundranode AS | Information & communication | 2025 |
| Thunheim Eiendom AS | Real estate | 2018 |
| Thunheim Holding AS | Wholesale & retail | 2018 |
| Thunheim Retail AS | Wholesale & retail | 1978 |
| Thur AS | Real estate | 2009 |
| Thylo AS | Administrative & support | 2022 |
| Tide Spirit AS | Transport & logistics | 2017 |
| Tidesmauet 4 AS | Real estate | 2023 |
| Tidewave Medical AS | Professional & scientific | 2017 |
| Tidy AS | Professional & scientific | 2016 |
| Tiffanys AS | Other services | 2024 |
| Tik Vision AS | Professional & scientific | 2016 |
| Til Leie AS | Administrative & support | 2021 |
| Til Livets Lykke AS | Hospitality | 2016 |
| Tild Norway AS | Information & communication | 2022 |
| Tildeg - Specialty Coffee & Atelier AS | | 2026 |
| Tilhold AS | Real estate | 2014 |
| Tilias AS | Real estate | 2016 |
| Timber Eiendom AS | Real estate | 2001 |
| Time and Date AS | Information & communication | 2005 |
| Time and Date Rights AS | Information & communication | 2020 |
| Timetrader AS | | 2014 |
| Timpelen Holding AS | Professional & scientific | 2014 |
| Tinngata 8 AS | Real estate | 2016 |
| Tinngata 8 Utvikling AS | Real estate | 2019 |
| Tinngata Eiendom AS | Real estate | 2020 |
| Tino Buggisch | Construction | 2006 |
| Tintswalo AS | | 2024 |
| Tintswalo Eiendom AS | Real estate | 2026 |
| Tiny Mobility Group AS | Wholesale & retail | 2021 |
| Tios Crewing AS | Mining & quarrying | 2010 |
| Tipshjørnet AS | Arts & recreation | 1997 |
| Tiral AS | Professional & scientific | 2017 |
| Tiram Invest AS | Real estate | 1989 |
| Tirb Eiendom AS | Real estate | 2007 |
| Tirna Holding AS | Wholesale & retail | 2005 |
| Titom AS | Wholesale & retail | 2000 |
| Tixly AS | Administrative & support | 2017 |
| TJ Finne AS | Financial services | 2007 |
| Tje Invest AS | | 2024 |
| Tjensvold AS | Wholesale & retail | 2023 |
| Tjensvold Investering AS | Arts & recreation | 2005 |
| Tjensvoll Hårdesign AS | Other services | 2000 |
| Tjensvoll Invest AS | Professional & scientific | 2023 |
| Tjentland Holding AS | | 2022 |
| Tjora Utvikling AS | Real estate | 2020 |
| Tjølsen AS | Wholesale & retail | 1998 |
| Tjølsen Holding AS | | 2020 |
| Tjøstheim Consulting AS | Information & communication | 2026 |
| TK Gjerde AS | Professional & scientific | 2014 |
| TK Holdco AS | Education | 2006 |
| TK Sæther AS | | 2020 |
| Tki AS | Professional & scientific | 2013 |
| TKK Digital AS | Information & communication | 2021 |
| Tkop Holding AS | | 2022 |
| Tla AS | Hospitality | 2020 |
| Tlhpro AS | Health & social care | 2020 |
| TM Birkeland Invest AS | Professional & scientific | 2014 |
| Tmbjelland Holding AS | | 2022 |
| TMG Norway AS | Professional & scientific | 2012 |
| TNB Kilden AS | Wholesale & retail | 2021 |
| Tnet Holding AS | Financial services | 2013 |
| TNG Technology AS | Professional & scientific | 2019 |
| Tntea AS | Wholesale & retail | 2024 |
| Tntvn AS | Financial services | 2007 |
| To Skritt Foran AS | Professional & scientific | 2024 |
| To-Mat Og Kjøkken AS | Hospitality | 2000 |
| Toaa Consult & Invest AS | | 2023 |
| Toaa Holding AS | | 2023 |
| Tob AS | Real estate | 2008 |
| Tobias Torstrup Eiendomsselskap AS | Real estate | 2020 |
| Tocap AS | Wholesale & retail | 1998 |
| Toco Eiendom AS | Real estate | 2020 |
| Todareistodo AS | | 2020 |
| Todnem Holding AS | | 2023 |
| Tofa Management AS | Financial services | 2007 |
| Toften Invest AS | | 2025 |
| Toggi Holding AS | | 2025 |
| Toha Holding AS | Hospitality | 2005 |
| Tollefsen Consulting AS | | 2020 |
| Tom Boye Holding AS | Real estate | 2022 |
| Tom Yum AS | | 2020 |
| Tomar AS | Real estate | 1994 |
| Tomat Kapital AS | | 2020 |
| Tomax AS | Administrative & support | 2005 |
| Tommeliten Barnehage SA | Education | 1994 |
| Tommy Ellingsen AS | Professional & scientific | 2024 |