| Skibs AS Varp | Real estate | 1942 |
| Skipsaksjeselskapet Ingrid | Financial services | 1951 |
| Skogveien 19 AS | Real estate | 2015 |
| Skyactive AS | Transport & logistics | 2023 |
| Sletta 11 AS | Construction | 2011 |
| Smokkiz AS | | 2023 |
| Snah Holding AS | Other services | 2013 |
| Snakk Tromsdalen AS | Wholesale & retail | 2001 |
| Snarby Invest AS | | 2021 |
| Snekkerbygg AS | Construction | 2003 |
| Snusnord AS | Wholesale & retail | 2021 |
| Snæcks AS | Wholesale & retail | 2024 |
| Solbakken Anlegg AS | Construction | 2019 |
| Solbu Holding AS | Professional & scientific | 2006 |
| Soler Eiendom AS | Real estate | 2023 |
| Solhaug Gård AS | Health & social care | 2023 |
| Sollied Security AS | Administrative & support | 2024 |
| Solutleie Tromsø Ans | Administrative & support | 2004 |
| Sorin Holding AS | Administrative & support | 2023 |
| Sportnord Gruppen AS | Wholesale & retail | 2005 |
| Sr-Eiendom AS | Real estate | 2024 |
| ST Multiservice AS | Construction | 2026 |
| Staff-Invest AS | Financial services | 2022 |
| Stangnes AS | Real estate | 2013 |
| Statnor AS | | 2013 |
| Stein Ivar Invest AS | | 2023 |
| Stensland Transport AS | Transport & logistics | 2022 |
| Stien Holding AS | | 2023 |
| Stien&Fredheim AS | Professional & scientific | 2023 |
| Stine Brandt Nilsen Trafikkopplæring AS | Education | 2025 |
| STK Transport AS | Transport & logistics | 2025 |
| Stokmo Media AS | Professional & scientific | 2020 |
| Studio - 7 AS | Arts & recreation | 2020 |
| Studiobox AS | Information & communication | 2018 |
| Styrmannsvegen 13 AS | Real estate | 2016 |
| Stødig Partner AS | Professional & scientific | 2022 |
| Svarthammeren Eiendom AS | Real estate | 2022 |
| Sveda Eiendom AS | | 2018 |
| Sverresvold Holding AS | Real estate | 2019 |
| Sykt Langt Nord AS | | 2023 |
| Systemutleie AS | Real estate | 2023 |
| Sørensen Takst AS | Professional & scientific | 2023 |
| Sørum Trading AS | Hospitality | 2009 |
| T En AS | Wholesale & retail | 2020 |
| T.A. Eiendom AS | Administrative & support | 2005 |
| T.E. Eiendom AS | Real estate | 1995 |
| Taddei Holding AS | | 2023 |
| Taico AS | Professional & scientific | 2015 |
| Taj-Holding AS | | 2023 |
| Takst Heimen AS | Real estate | 2024 |
| Tannlege Synne Mikkelsen AS | Health & social care | 2020 |
| TBN AS | | 2013 |
| Tefrum/Stark Eiendom AS | Real estate | 2024 |
| Terna Invest AS | Real estate | 2005 |
| The Arctic Villa AS | Real estate | 2020 |
| The Honest Travel AS | Information & communication | 2025 |
| Thomas Hay AS | Education | 2018 |
| Thorkildsen AS | Professional & scientific | 1998 |
| Thp-Holding AS | | 2023 |
| Tidens AS | Real estate | 2019 |
| Tind Bygg AS | Construction | 2026 |
| Tind Konsult AS | Real estate | 1989 |
| Tinden Byggservice AS | Construction | 2017 |
| Tindtunnelen Tromsø AS | Professional & scientific | 2016 |
| Tj-Invest AS | | 2023 |
| TL Sveis AS | Manufacturing | 2024 |
| TNB Pyramiden AS | Wholesale & retail | 2025 |
| Toarja Holding AS | | 2008 |
| Tole Invest AS | Professional & scientific | 2020 |
| Tomerich Holding AS | Health & social care | 2021 |
| Torneus Utvikling AS | Real estate | 2018 |
| Torstind Eiendom AS | Real estate | 2024 |
| Torvtak AS | | 2022 |
| Trademan AS | Wholesale & retail | 2003 |
| Tre Kokker På Hjul AS | Hospitality | 2026 |
| Trem Holding AS | Real estate | 2017 |
| Triumf Rør AS | Construction | 2018 |
| Troms Boligselskap AS | Real estate | 2020 |
| Troms Bygg Og Eiendoms Service AS | Construction | 2021 |
| Troms Fryseterminal AS | Transport & logistics | 1997 |
| Troms Lagerutleie AS | Real estate | 2013 |
| Troms Maskin Og Service AS | Manufacturing | 2021 |
| Troms Seafood AS | Wholesale & retail | 1999 |
| Tromsdalen Byutvikling AS | Real estate | 2001 |
| Tromsdalen Dekk Og Oljeservice AS | Other services | 2021 |
| Tromsdalen Elektro AS | Construction | 2010 |
| Tromsdalen Invest AS | | 2019 |
| Tromsdalen Legesenter Da | Health & social care | 2024 |
| Tromsdalshavna SA | Transport & logistics | 1975 |
| Tromsø Budget Tours AS | Administrative & support | 2017 |
| Tromsø Bygg Og Renovering AS | Construction | 2021 |
| Tromsø Dyreklinikk AS | Professional & scientific | 2022 |
| Tromsø Engineering AS | Professional & scientific | 1988 |
| Tromsø Fastland Beitelag SA | Agriculture & fishing | 2021 |
| Tromsø Håndverkerlag AS | Construction | 2015 |
| Tromsø Minilager AS | Real estate | 2019 |
| Tromsø Powder Guides AS | Administrative & support | 2026 |
| Tromsø Rental AS | Administrative & support | 2024 |
| Tromsø Sweater Shop Ans | Wholesale & retail | 1998 |
| Tromsø Takmontering AS | Construction | 1989 |