| Tromsø Ice Domes AS | | 2024 |
| Tromsø III AS | Hospitality | 2025 |
| Tromsø Industripark AS | Real estate | 2008 |
| Tromsø Jernbanestasjon AS | Hospitality | 2010 |
| Tromsø Julemagasin AS | Wholesale & retail | 2026 |
| Tromsø Karaoke AS | Administrative & support | 2019 |
| Tromsø Kiropraktikksenter AS | Health & social care | 2013 |
| Tromsø Kirurgiske Senter AS | Real estate | 2024 |
| Tromsø Kjøkken & Interiør AS | Wholesale & retail | 2018 |
| Tromsø Klatresenter AS | Arts & recreation | 2019 |
| Tromsø Kulkran AS | Real estate | 1928 |
| Tromsø Lodge AS | Administrative & support | 2019 |
| Tromsø Marine Service AS | Manufacturing | 2006 |
| Tromsø Maritime Næringspark AS | Real estate | 2012 |
| Tromsø Maskin Og Transport AS | Transport & logistics | 2016 |
| Tromsø Maskin Og Utemiljø AS | Construction | 2014 |
| Tromsø Maskin Team AS | Construction | 2021 |
| Tromsø Maxitaxi Ans | Transport & logistics | 2015 |
| Tromsø Media AS | Information & communication | 2011 |
| Tromsø Medisinske Senter AS | Real estate | 2005 |
| Tromsø Mekaniske AS | Manufacturing | 2001 |
| Tromsø Mikrobryggeri AS | Manufacturing | 2015 |
| Tromsø Motor & Diagnoseservice AS | Manufacturing | 2017 |
| Tromsø Musikkskole AS | Arts & recreation | 2012 |
| Tromsø Møbelstopp AS | Manufacturing | 2020 |
| Tromsø Nohafa AS | Hospitality | 2005 |
| Tromsø Næringseiendom AS | Real estate | 2017 |
| Tromsø Næringsmegling AS | Real estate | 2004 |
| Tromsø Offentlige Parkering AS | Transport & logistics | 2014 |
| Tromsø Optikk AS | Wholesale & retail | 2007 |
| Tromsø Osteopati AS | Health & social care | 2024 |
| Tromsø Outdoor AS | Arts & recreation | 2016 |
| Tromsø Parkering AS | Transport & logistics | 2013 |
| Tromsø Parkett- Og Golvservice Ans | Construction | 1987 |
| Tromsø Properties AS | Real estate | 2024 |
| Tromsø Psykologtjeneste AS | Health & social care | 2025 |
| Tromsø Rengjøring AS | Administrative & support | 2020 |
| Tromsø Rental Hub AS | Hospitality | 2023 |
| Tromsø Restaurantdrift Da | Hospitality | 2004 |
| Tromsø Rettshjelp AS | | 2024 |
| Tromsø Rørleggerforretning AS | Construction | 1997 |
| Tromsø Rørservice AS | Construction | 2022 |
| Tromsø Seafood AS | Wholesale & retail | 2021 |
| Tromsø Sentrum AS | Professional & scientific | 2017 |
| Tromsø Ski & Sykkel AS | Wholesale & retail | 2009 |
| Tromsø Ski Guides AS | Administrative & support | 2020 |
| Tromsø Skipsmegling AS | Transport & logistics | 2025 |
| Tromsø Skipsservice AS | Manufacturing | 2023 |
| Tromsø Skipsverft AS | Real estate | 2000 |
| Tromsø Skomakerverksted Rolf Aarberg & Sønn Ans | Other services | 1998 |
| Tromsø Skotøimagasin AS | Wholesale & retail | 1928 |
| Tromsø Sosiale Entreprenørskap AS | Hospitality | 2015 |
| Tromsø Spesialistlegedrift Da | Health & social care | 2007 |
| Tromsø Sport AS | Wholesale & retail | 2005 |
| Tromsø Stein Invest AS | | 2019 |
| Tromsø Takst Nord Allertsen.No AS | Professional & scientific | 2016 |
| Tromsø Tannkirurgi Og Narkosesenter AS | Health & social care | 2018 |
| Tromsø Tannlegesenter AS | Health & social care | 2020 |
| Tromsø Tannteknikk AS | Manufacturing | 1994 |
| Tromsø Tapet & Linoleumslager AS | Wholesale & retail | 1980 |
| Tromsø Taxi AS | Transport & logistics | 2001 |
| Tromsø Trafikkskolesenter AS | Education | 1994 |
| Tromsø Utbygging AS | Real estate | 2006 |
| Tromsø Utleie AS | Administrative & support | 2015 |
| Tromsø Utvikling AS | Real estate | 2016 |
| Tromsø Varmepumpeservice AS | Construction | 2023 |
| Tromsø Verktøy & Industri AS | Wholesale & retail | 2026 |
| Tromsø Vikarbyrå AS | Administrative & support | 2011 |
| Tromsø VVS AS | Construction | 2025 |
| Tromsø World Festival AS | Arts & recreation | 2022 |
| Tromsøadvokatene AS | Professional & scientific | 2007 |
| Tromsøhallen Da | Administrative & support | 1997 |
| Tromsøterminalen AS | Transport & logistics | 1999 |
| Tromsøterminalen Eiendom AS | Real estate | 2017 |
| Tromsøya Eiendom AS | Real estate | 2008 |
| Tromsøya Legesenter AS | Health & social care | 2024 |
| Tromsøysundvegen 5 AS | Real estate | 2015 |
| Tromsøysundvegen 80 AS | Real estate | 1998 |
| Tromsøysundveien 266 AS | Real estate | 2018 |
| Tromtind AS | Real estate | 2024 |
| Trond Arntsen Eiendom AS | Real estate | 2011 |
| Trond B. Kristoffersen AS | Health & social care | 2016 |
| Trond Mikalsen Holding AS | | 2021 |
| Trondongan AS | Financial services | 2022 |
| Trondsen Auto AS | Wholesale & retail | 2021 |
| Trondsen Holding AS | Real estate | 2005 |
| Trones Holding AS | Financial services | 2005 |
| Trones Invest AS | Real estate | 2017 |
| Trosaf AS | Construction | 2025 |
| Trova AS | Professional & scientific | 2017 |
| TRP - Bygg AS | Construction | 2023 |
| Trurask Holding AS | | 2025 |
| Trves 551 Holding AS | | 2023 |
| Tråkk 9000 AS | Other services | 2020 |
| Tse Event AS | Administrative & support | 2020 |
| TT Finans Tromsø AS | | 2021 |
| TT Tekniske Tjenester AS | Construction | 2018 |
| Ttcom AS | Wholesale & retail | 2011 |
| TTR Invest AS | Administrative & support | 2022 |
| Tuesday AS | Real estate | 2019 |