| Tgcm AS | Administrative & support | 2005 |
| TGR Tech Ventures AS | Information & communication | 2017 |
| TH Utvikling AS | Real estate | 1975 |
| Thamm Holding AS | | 2024 |
| The Arctic Resort Company AS | Administrative & support | 2025 |
| The Arctic Resort Company Holding AS | | 2026 |
| The Arctic Travel Company AS | | 2024 |
| The Box of Mothers Ans | Arts & recreation | 2008 |
| The Front Tromsø AS | Real estate | 1943 |
| The Gem Rentals AS | Real estate | 2022 |
| The Gift Box AS | Wholesale & retail | 2026 |
| The Norwegian Travel Company AS | Administrative & support | 2019 |
| The Norwegian Travel Company Holding AS | Transport & logistics | 2021 |
| Themine AS | | 2019 |
| Thereses Trafikkskole AS | Education | 2018 |
| Thermaltech AS | Energy | 2024 |
| Thewan AS | Professional & scientific | 2021 |
| THG AS | Professional & scientific | 2016 |
| Thodan Holding AS | | 2026 |
| THP Eiendom AS | Real estate | 2023 |
| Thranes Invest AS | | 2026 |
| Ti-Holding AS | Financial services | 2016 |
| Tiggerstaven AS | | 2023 |
| Til Fotball AS | Arts & recreation | 2009 |
| Tillitum AS | Professional & scientific | 2025 |
| Tilo Holding AS | Professional & scientific | 2019 |
| Tilpasset Bolig AS | Real estate | 2014 |
| Tind Holding Tromsø AS | Real estate | 2019 |
| Tistaad AS | Real estate | 2024 |
| Tistaad Swift AS | Real estate | 2026 |
| Tja AS | Information & communication | 2018 |
| Tje Holding AS | Financial services | 2017 |
| Tjo Consulting AS | Real estate | 1989 |
| TLH Holding AS | Real estate | 2020 |
| TM & Baltha AS | Hospitality | 2021 |
| Tmek Eiendom AS | Real estate | 2022 |
| TMH Kapital AS | Real estate | 2026 |
| TMT Music AS | Arts & recreation | 2019 |
| TNB Jekta AS | Wholesale & retail | 2005 |
| Tobeha AS | | 2023 |
| Tocatel AS | | 2001 |
| Tocatel Invest AS | Real estate | 2023 |
| Toccata AS | Administrative & support | 2023 |
| Tof-Huset SA | Real estate | 1986 |
| Toftveien Barnehage SA | Education | 1991 |
| Toha Eiendom AS | Real estate | 2005 |
| Tollbodstranda AS | Real estate | 2017 |
| Tollefsen Eiendom AS | Real estate | 2021 |
| Tolou AS | Information & communication | 2024 |
| Tom & Mona AS | Arts & recreation | 2023 |
| Tom-Erik Nyborg Holding AS | Construction | 2017 |
| Toma Eiendom AS | Real estate | 1997 |
| Tomallo Holding AS | Real estate | 2019 |
| Tomasjordnes Eiendom AS | Real estate | 2013 |
| Tomasjordnes Marina AS | Real estate | 2015 |
| Tomei Holding AS | | 2023 |
| Tomt 666 AS | Real estate | 2014 |
| Tomt 680 AS | Real estate | 2017 |
| Tonto AS | Real estate | 2014 |
| Tonto Boligutleie AS | Real estate | 2020 |
| Tonto Utvikling AS | Real estate | 2019 |
| Top G Consulting AS | Professional & scientific | 2023 |
| Tor Sebergsen AS | Wholesale & retail | 1985 |
| Tor-Steinar's Trafikkskole AS | Education | 2013 |
| Torghatten Nord AS | Transport & logistics | 2008 |
| Torherold AS | Professional & scientific | 2020 |
| Torshov Sport Tromsø AS | Wholesale & retail | 2013 |
| Torsk Development AS | Information & communication | 2024 |
| Torunn Tøllefsen Interiørarkitekt AS | Professional & scientific | 2006 |
| Tos AS | Real estate | 2025 |
| Tos Lab AS | Professional & scientific | 1998 |
| Tosi Transport AS | Transport & logistics | 2012 |
| Tosom Invest AS | Real estate | 2018 |
| Total Apartments AS | Hospitality | 2021 |
| Total Eiendom AS | Real estate | 1996 |
| Total Prosjekt AS | Real estate | 1999 |
| Total Renovering - Franko Service AS | Construction | 2022 |
| TOTAL2025 AS | Real estate | 2025 |
| TOTAL2026 AS | Real estate | 2025 |
| Totalrenovering AS | Construction | 1996 |
| Totalteq AS | Real estate | 2018 |
| Toucan AS | Administrative & support | 2020 |
| Touring Cars Norway AS | Wholesale & retail | 2021 |
| Touristshop Tromsø AS | Wholesale & retail | 2025 |
| Touristshop Tromsø Havn AS | Administrative & support | 2025 |
| Tourphotos AS | Wholesale & retail | 2017 |
| TR. Holding AS | Administrative & support | 2015 |
| TR. Invest AS | Real estate | 2015 |
| Traasdahl AS | Wholesale & retail | 1999 |
| Traasdahl Eiendom AS | Wholesale & retail | 1991 |
| Traasdahl Invest AS | | 2026 |
| Transport Og Graveservice AS | Transport & logistics | 2017 |
| Transportsentralen Tromsø Eiendom AS | Real estate | 2015 |
| Transportsentralen Tromsø SA | Transport & logistics | 1969 |
| TRD Holding AS | | 2025 |
| Tre - Kløver Ans | Transport & logistics | 2015 |
| Trefoten Film AS | Information & communication | 2025 |
| Trening Nord AS | Arts & recreation | 2019 |
| Treningsforum Da | Information & communication | 2008 |
| Treningskompis Da | Health & social care | 2024 |