| Toyota Bilia AS | Wholesale & retail | 1999 |
| TP Byggentreprenør AS | Construction | 2019 |
| TP Management AS | Professional & scientific | 2017 |
| TP Solutions AS | Professional & scientific | 2016 |
| TP2 Holding AS | Real estate | 2022 |
| TPC Eiendom A/S | Real estate | 1898 |
| TPP Holding AS | Construction | 2022 |
| Tpvh Holding AS | | 2026 |
| TR Råd AS | Professional & scientific | 2025 |
| Traba AS | Health & social care | 2020 |
| Tracato AS | Wholesale & retail | 2022 |
| Traced AS | Information & communication | 2021 |
| Trada AS | Financial services | 2017 |
| Tradeconsult AS | Wholesale & retail | 1995 |
| Trafikksikker AS | Education | 2013 |
| Trakteriet AS | Education | 2025 |
| Traktoli AS | Real estate | 2017 |
| Tramonto AS | Real estate | 2001 |
| Trampa Eiendom AS | Real estate | 2013 |
| Trana Eiendom Holding AS | Real estate | 2005 |
| Trane Holding AS | | 2021 |
| Transitten Eiendom AS | Real estate | 2000 |
| Transittkaia Kvartal 1 AS | Real estate | 2024 |
| Transittkaia Kvartal 2 AS | Real estate | 2024 |
| Transittkaia Kvartal 3 AS | Real estate | 2024 |
| Transport Trøndelag AS | Transport & logistics | 2025 |
| Transporting 24-7 AS | Transport & logistics | 2022 |
| Transportkjøling Midt-Norge AS | Wholesale & retail | 2008 |
| Transportkjøling Norge AS | Construction | 2018 |
| Transportteam Trøndelag AS | Transport & logistics | 2017 |
| Transylvania Tolketjenester AS | Professional & scientific | 2019 |
| Tranås Logistikk Invest AS | Real estate | 2019 |
| Trapdoor Holding AS | Financial services | 2012 |
| Trappvask AS | Administrative & support | 2020 |
| Travbanevegen 7 AS | Real estate | 2020 |
| Travbaneveien 1 AS | Real estate | 2000 |
| Travbaneveien 3 AS | Real estate | 1998 |
| Travbaneveien 5 AS | Real estate | 2000 |
| Travbaneveien Invest AS | Real estate | 2013 |
| Travel-Tek AS | Information & communication | 2020 |
| Travelnet Norway AS | Administrative & support | 2008 |
| Travelnet Reisevarehuset AS | Administrative & support | 1990 |
| Travely Media SA | Professional & scientific | 2022 |
| Trawl Tech AS | Wholesale & retail | 2025 |
| TRD L AS | Transport & logistics | 2020 |
| TRD Live AS | Arts & recreation | 2018 |
| TRD Travel AS | Administrative & support | 1998 |
| Tre AS | Professional & scientific | 2017 |
| Tre Forvaltning AS | | 2018 |
| TRE40FIRE Da | Arts & recreation | 2023 |
| Trebo Bolig AS | Construction | 2016 |
| Tredos Invest AS | Real estate | 1999 |
| Trefjorten AS | Financial services | 2018 |
| Trefolk AS | Administrative & support | 2019 |
| Trefyren AS | | 2019 |
| Tregore Oü | Construction | 2012 |
| Trekanten Eiendom Og Drift AS | Real estate | 2005 |
| Trekanten Invest AS | Real estate | 2005 |
| Trekanttomten Nedre Elvehavn AS | Real estate | 1999 |
| Treklossen AS | Health & social care | 2025 |
| Trend Modellbyrå AS | Professional & scientific | 1988 |
| Trend-Y AS | Wholesale & retail | 2004 |
| Trener Robotics Norge AS | Information & communication | 2025 |
| Trenher AS | Arts & recreation | 2023 |
| Treningsklinikken AS | Health & social care | 2023 |
| Trenpånett.No AS | Education | 2013 |
| Tresbygg AS | Construction | 2012 |
| Tress Utvikling AS | Real estate | 2019 |
| Trevis Consulting AS | Information & communication | 2015 |
| TRH Prosjekt AS | Real estate | 2013 |
| TRH Stage AS | Arts & recreation | 2020 |
| TRH Utvikling AS | Professional & scientific | 2013 |
| TRH Venues AS | Real estate | 2024 |
| TRH X AS | Professional & scientific | 2026 |
| Tribunebygg AS | Real estate | 2015 |
| Tributum AS | Administrative & support | 1986 |
| Trickwik AS | Arts & recreation | 2017 |
| Trilax Center Trondheim Ans | | 1989 |
| Trim IT AS | Other services | 2026 |
| Trine Fossum AS | Professional & scientific | 2025 |
| Trine H-L AS | Financial services | 2017 |
| Trine Invest AS | Financial services | 2005 |
| Trines Hundesalong AS | Agriculture & fishing | 2004 |
| Trio Alpaca Da | Arts & recreation | 2003 |
| Trio Bravo Da | Arts & recreation | 1997 |
| Trio No Treble Da | Arts & recreation | 2018 |
| Triosphere Da | Arts & recreation | 2011 |
| Tripla Invest AS | Real estate | 2016 |
| Triply AS | Wholesale & retail | 2016 |
| Trippel S Invest AS | Real estate | 2023 |
| Tripticon Media Design Da | Information & communication | 1999 |
| Trivionics Technologies AS | Professional & scientific | 2025 |
| TRM Holding AS | Professional & scientific | 2008 |
| Tro Tjenere Da | Information & communication | 2001 |
| Trohld AS | | 2025 |
| Troillan Holding AS | Real estate | 2020 |
| Troisman AS | Construction | 2013 |
| Trojo Holding AS | | 2026 |
| Troka Import Trond Asbølmo Og Karl Lindtner Ans | Wholesale & retail | 1990 |
| Troll Hundefor AS | Wholesale & retail | 1998 |