| Teeja AS | | 2016 |
| Teh Invest AS | | 2024 |
| Tema Regnskap Øst AS | Professional & scientific | 1991 |
| Temac Invest AS | Real estate | 2017 |
| Tenito AS | Real estate | 2005 |
| Tenstar Simulation Norway AS | Information & communication | 2022 |
| Terabyte AS | Information & communication | 2018 |
| Terabyte Holding AS | Information & communication | 2017 |
| Teracoach AS | Education | 2025 |
| Terminalbygg AS | Real estate | 1986 |
| Testdeg AS | Wholesale & retail | 2014 |
| Tex-Pizzaen AS | Wholesale & retail | 1991 |
| Texo AS | Real estate | 2018 |
| TF Holding AS | Real estate | 1988 |
| TG Takst AS | Professional & scientific | 2020 |
| TG Totalservice AS | Administrative & support | 2017 |
| Tgbe AS | Administrative & support | 2024 |
| TH Catering AS | Hospitality | 2019 |
| TH Service AS | Construction | 2017 |
| Thanstrøm Bil AS | Wholesale & retail | 1992 |
| The Ict Company AS | Energy | 2012 |
| Thinthan Thaifood AS | Hospitality | 2012 |
| Thmno AS | | 2023 |
| Thomas Jahnsen Revisjon Og Eiendom AS | | 2021 |
| Thomas Rimul AS | Arts & recreation | 2022 |
| Thomas Severinsen Transport AS | Transport & logistics | 2021 |
| Thomsen Lie Eiendom AS | Real estate | 2010 |
| Thomsen Lie Holding AS | Wholesale & retail | 2005 |
| Thors Garage AS | Wholesale & retail | 2012 |
| Thors Maskin AS | Construction | 2013 |
| Til Invest AS | Construction | 2018 |
| Timian Eiendom AS | Real estate | 2004 |
| Tista AS | Real estate | 2005 |
| Tista Eiendom AS | Real estate | 2010 |
| Tista Eiendomsselskap AS | Real estate | 2021 |
| Tista Synssenter AS | Wholesale & retail | 2022 |
| TJ Anleggsteknikk AS | Construction | 2023 |
| TJ Service Halden AS | Administrative & support | 2023 |
| Tjernes Holding AS | Wholesale & retail | 2015 |
| TK Service AS | Construction | 2023 |
| TLM Eiendomsutleie AS | Real estate | 2021 |
| Tma Veiassistanse AS | Transport & logistics | 2023 |
| To-Jo Elektro AS | Construction | 2020 |
| Tollbugata Drift AS | Hospitality | 2018 |
| Tollfokus AS | Transport & logistics | 2020 |
| Tom Rådgivning AS | Professional & scientific | 1989 |
| Tomta Transport AS | Transport & logistics | 1991 |
| Ton-Tree AS | Construction | 2022 |
| Toppen Investering AS | Arts & recreation | 2021 |
| Toppen Malerfirma AS | Construction | 1988 |
| Toppen Rådgivning AS | Professional & scientific | 2025 |
| Torget 5 AS | Real estate | 2003 |
| Torp & Torp Holding AS | | 2025 |
| Torpedal Trevare Og Utemiljø AS | Manufacturing | 2015 |
| Torvet Mat AS | Wholesale & retail | 2020 |
| Totalløsning AS | Administrative & support | 2023 |
| Tran Revisjon AS | Professional & scientific | 2015 |
| Tranbok AS | Construction | 2023 |
| Trancorp AS | Information & communication | 2003 |
| Travinfo Norge Ans | Information & communication | 2000 |
| Tre Kokker AS | Hospitality | 2021 |
| Treningssenter AS | Arts & recreation | 2021 |
| Tresgaard Invest AS | Real estate | 1976 |
| Trevi S.P.A Nuf | Construction | 2007 |
| Trevirk AS | Agriculture & fishing | 2023 |
| Tribus Transport AS | Transport & logistics | 2024 |
| Trida AS | Wholesale & retail | 1993 |
| Trolltangen Naturbarnehage AS | Education | 2022 |
| Trovex AS | Wholesale & retail | 2025 |
| Trust IT AS | Information & communication | 2001 |
| Trylo AS | Real estate | 2014 |
| Tuffa Tider Da | Arts & recreation | 2025 |
| Tune AS | Real estate | 2016 |
| Tuneto AS | Health & social care | 2023 |
| Tungservice AS | Transport & logistics | 2018 |
| Tunsli Consult AS | Professional & scientific | 2021 |
| Twice Holding AS | | 2021 |
| Tyven Records Da | Arts & recreation | 2026 |
| Tåkeheimen Eiendom AS | Real estate | 1989 |
| Tøltrider AS | Wholesale & retail | 2016 |
| Tømrerfirma Andreas Nilsen AS | Construction | 2026 |
| Tømrerfirma Christer Wang AS | Construction | 2015 |
| Tømrerfirma Eriksson & Andersen AS | Construction | 2014 |
| Tømrerfirma Magne H Karlsen & Sønn AS | Construction | 2015 |
| Tømrerfirma Rune Olsen AS | Construction | 2004 |
| Tømrermester J a Hansen Eftf AS | Construction | 2008 |
| Tømrermester Ronny Hansen AS | Construction | 2014 |
| Tørst Bryggeri AS | Manufacturing | 2023 |
| Tørvis Hotell AS | Hospitality | 2021 |
| Udda Family AS | Transport & logistics | 2020 |
| Udda Holding AS | Transport & logistics | 2020 |
| Ullevålsveien 116 AS | Real estate | 2016 |
| Ulvås Holding AS | Construction | 2012 |
| Unicare Bakke AS | Health & social care | 2004 |
| Uniped AS | Health & social care | 2011 |
| Unneberg Holding AS | Agriculture & fishing | 2012 |
| Unneberg Invest AS | Real estate | 2015 |
| Unneberg Skogsdrift AS | Agriculture & fishing | 2012 |
| Urban Olsson Bygg & Industriservice AB | Construction | 2011 |
| Vakker Stil Katrine G AS | Other services | 2012 |