| Torp Kontorinvest AS | Real estate | 2014 |
| Torplien AS | Real estate | 2021 |
| Tors Vei Garasjelag SA | Real estate | 1979 |
| Torsby Drift AS | Information & communication | 2023 |
| Toss AS | Transport & logistics | 2018 |
| Total Coating AS | Manufacturing | 2013 |
| Total Entreprenør Partner AS | Real estate | 2017 |
| Totorina AS | Wholesale & retail | 2024 |
| Touch of Heaven AS | Arts & recreation | 2018 |
| Tourmentum AS | Real estate | 2026 |
| Tovslid Invest AS | | 2023 |
| Toyota Buskerud AS | Other services | 1988 |
| Toyota Insurance Management Nuf | Financial services | 2022 |
| Toyota Kreditbank GmbH Nuf | Financial services | 1997 |
| Toyota Logistics Services Norway AS | Transport & logistics | 2002 |
| Toyota Motor Europe Nv/Sa | Wholesale & retail | 2000 |
| Toyota Norge AS | Wholesale & retail | 1996 |
| TP Miljøteknikk AS | Professional & scientific | 1988 |
| Tp-Products AS | Manufacturing | 1968 |
| Trac Holding AS | Professional & scientific | 2011 |
| Trackson AS | Professional & scientific | 2012 |
| Tradeadvantix AS | Information & communication | 2026 |
| Trading by the River AS | Wholesale & retail | 2022 |
| Trafico AS | Real estate | 1992 |
| Trafikklærer Erna AS | Education | 2021 |
| Trankaur AS | Wholesale & retail | 2024 |
| Transformation Consulting AS | Professional & scientific | 2026 |
| Transigo AS | Transport & logistics | 2025 |
| Transport Og Anleggsservice AS | Administrative & support | 2018 |
| Transportsenteret AS | Transport & logistics | 1990 |
| Transportweb AS | Information & communication | 2023 |
| Transtor Shipping AS | Transport & logistics | 2003 |
| Trappeconsult AS | Administrative & support | 1989 |
| Tre Ganger Steen AS | Real estate | 1981 |
| Trebo AS | Construction | 2020 |
| Trebo Drift AS | Administrative & support | 2020 |
| Trebo Holding AS | Construction | 2020 |
| Trelleborg Byggeprodukter AB | Wholesale & retail | 1996 |
| Trend Eiendomsinvest AS | Construction | 2018 |
| Trend Hus AS | Construction | 2014 |
| Trendsetters AS | Wholesale & retail | 2025 |
| Tres Hombres Invest AS | Real estate | 2021 |
| Treschowsgate 1 Og 3 AS | Real estate | 2021 |
| Treschowsgate 1-3 AS | Real estate | 2020 |
| Treschowsgate AS | Real estate | 2010 |
| Trevirket Eiendom AS | Real estate | 2021 |
| Triaden Trafikkskole AS | Education | 2025 |
| Tribunen AS | | 2021 |
| Trilde AS | Professional & scientific | 2020 |
| Trim Team AS | Education | 2019 |
| Trimakk Nor AS | Wholesale & retail | 2007 |
| Trimmen AS | Real estate | 2008 |
| Trimmeren Drammen AS | Real estate | 2026 |
| Trimromeksperten Da | Wholesale & retail | 1997 |
| Trio Import Og Export Da | Wholesale & retail | 2021 |
| Trippel Eiendom AS | Real estate | 2000 |
| Trippel Holding AS | Real estate | 2016 |
| Trippel Næringseiendom AS | Real estate | 2019 |
| Trippelseven AS | Wholesale & retail | 2025 |
| Trisway Bygg Nuf | Construction | 2020 |
| Troll Teko Holding AS | Real estate | 2023 |
| Trollsrudmoen Deponi AS | Water & waste | 2022 |
| Trolsrud Elektro AS | Construction | 2018 |
| Trolsrud Holding AS | Construction | 2016 |
| Trommeveien AS | Real estate | 2019 |
| Tromsøya Eiendomsinvest AS | Real estate | 2021 |
| True North PMM Ltd Nuf | Professional & scientific | 2024 |
| Trust Few Clothing AS | Wholesale & retail | 2020 |
| Try Aagesen Invest AS | | 2020 |
| Try Norway AS | Administrative & support | 1998 |
| Trygg Helse AS | Wholesale & retail | 2020 |
| Trygg Malerservice AS | Construction | 2022 |
| Trygg Vei AS | Transport & logistics | 2026 |
| Trykk Service AS | Manufacturing | 1973 |
| Trykon Boligutvikling AS | Real estate | 2017 |
| Tryllepapp AS | Wholesale & retail | 2025 |
| Trysilbygg AS | Construction | 1990 |
| Trysilhus Akershus AS | Real estate | 2001 |
| Trysilhus Areal AS | Real estate | 1986 |
| Trysilhus AS | Real estate | 1990 |
| Trysilhus Boligservice AS | Construction | 2015 |
| Trysilhus Buskerud AS | Real estate | 2019 |
| Trysilhus Nordøst AS | Real estate | 2006 |
| Trysilhus Partner AS | Real estate | 2014 |
| Trysilhus Sørøst AS | Real estate | 2006 |
| Trysilhus Tomt AS | Real estate | 2006 |
| Trysilhus Trykon AS | Real estate | 2014 |
| Trysilhus Unibo AS | Real estate | 2014 |
| Trysilhus Øst AS | Real estate | 1999 |
| Trysilhusgruppen Ansatte AS | | 2019 |
| Trysilhusgruppen AS | Real estate | 2007 |
| Tryterud Skog V/Falck-Pedersen Ans | Agriculture & fishing | 2010 |
| Tråkka 5 AS | Real estate | 2019 |
| TSB Invest AS | | 2018 |
| TT Auto AS | Wholesale & retail | 2023 |
| TT Dalen AS | Administrative & support | 2015 |
| TT Hans AS | Wholesale & retail | 2021 |
| TT Helse & Rådgivning AS | Arts & recreation | 2024 |
| TT Investment AS | | 2008 |
| Tudor Holding AS | Wholesale & retail | 2015 |