| Sállir Natur AS | Professional & scientific | 2020 |
| Sæterelva Eiendom AS | Real estate | 2015 |
| Sætermo AS | Real estate | 2015 |
| Sæteråsen Holding AS | Administrative & support | 2021 |
| Sæteråsen Maskin AS | Construction | 2012 |
| Sæteråsen Sag Og Høvleri AS | Manufacturing | 2006 |
| Sæteråsen Utleie AS | Administrative & support | 2021 |
| Søndre Kilbotn Grunneierlag SA | Real estate | 2011 |
| Sønner Og Datter AS | Real estate | 2021 |
| Sør-Troms Elektro AS | Construction | 2025 |
| Sørensen Bilskade Service AS | Other services | 2012 |
| Sørensen Invest AS | Real estate | 1997 |
| Sørheia Invest AS | Real estate | 2019 |
| Sørsia Eiendom AS | Real estate | 1992 |
| Sørsia-Fysioterapi AS | Health & social care | 2024 |
| T Berset Holding AS | Health & social care | 1999 |
| T Erlandsen Holding AS | Construction | 2021 |
| T Henriksen Invest AS | | 2025 |
| T Henriksen Transport AS | Transport & logistics | 2025 |
| T-M Holding AS | Real estate | 2005 |
| T. Hatteberg Iversen Eiendom AS | Health & social care | 2012 |
| T.Edvardsen Holding AS | Administrative & support | 2020 |
| T.N. Invest AS | Real estate | 2016 |
| Tais Holding AS | Professional & scientific | 2012 |
| Tak Service AS | Construction | 2018 |
| Takstingeniør Tore Rekkedal AS | Professional & scientific | 2013 |
| Takstteam Harstad AS | Professional & scientific | 2025 |
| Talga Cosmetics AS | Manufacturing | 2026 |
| Talga Invest AS | | 2026 |
| Tandesjøvoll AS | Financial services | 2017 |
| Tannlege Christine Jarling AS | Health & social care | 2014 |
| Tannlege Ina Lindahl Halvorsen AS | Health & social care | 2021 |
| Tannlege Lasse Johansen AS | Health & social care | 2012 |
| Tannlege Marthe Berg Isaksen AS | Health & social care | 2020 |
| Tannlege Tone-Lise Karlsen AS | Health & social care | 2025 |
| Tannpleier Janne Igeland AS | Health & social care | 2021 |
| Tapp Harstad AS | Hospitality | 2023 |
| Taste of the Arctic AS | Arts & recreation | 2022 |
| Tbaar Invest AS | Real estate | 2007 |
| Team Eriksen Drift AS | Construction | 2025 |
| Teamlind.No AS | Other services | 2012 |
| Teknisk Bureau Harstad AS | Other services | 2015 |
| Teknisk Bureau Last Harstad AS | Other services | 2017 |
| Teknisk Drift AS | Real estate | 2022 |
| Teknobingo Harstad AS | Arts & recreation | 2004 |
| Teneo Infra AS | Information & communication | 2014 |
| Tennvassåsen-Sørli Grunneierlag SA | Real estate | 2015 |
| Tennøy AS | | 2017 |
| Tequila Sports Beyond AS | Wholesale & retail | 2006 |
| Terje Killi AS | Construction | 2018 |
| Terminaldrift Nord AS | Manufacturing | 2018 |
| TGS Investa AS | Education | 2012 |
| Thermo Control Nord AS | Wholesale & retail | 1988 |
| Thinlight Norge AS | Wholesale & retail | 2013 |
| THN Tannpleie AS | Health & social care | 2026 |
| Thomas Johnsen Dagligvare AS | Wholesale & retail | 2025 |
| Ti Multiservice AS | Administrative & support | 2018 |
| Tian AS | Professional & scientific | 2017 |
| Tian Eiendom Gimsøy AS | Real estate | 2026 |
| Tian Helse AS | Health & social care | 2019 |
| Tian Helse Eiendom AS | Real estate | 2020 |
| Tian Helse Holding AS | Health & social care | 2020 |
| Tian Holding AS | Health & social care | 2007 |
| Tian Invest AS | | 2016 |
| Tian Næringseiendom AS | Health & social care | 2017 |
| Tib Holding AS | Real estate | 2005 |
| Tico Invest AS | | 2021 |
| Tid Og Penger AS | Professional & scientific | 2005 |
| Tiketalen 4 AS | Real estate | 2023 |
| Tine Kristiansen Holding AS | Financial services | 2014 |
| Tinja AS | Health & social care | 2003 |
| Tjeldsund Tide AS | Hospitality | 2025 |
| Tjeldsundveien 565 AS | Real estate | 2023 |
| Tjeldsundveien Holding AS | Transport & logistics | 2022 |
| Tke Eiendom AS | Real estate | 2019 |
| TKM Holding AS | Construction | 2018 |
| TLB Holding AS | Financial services | 2017 |
| TN Eiendom Narvik AS | Real estate | 2018 |
| TN Mølnholtet 42 AS | Real estate | 2016 |
| TN Storåkeren AS | Health & social care | 2017 |
| TNB Harstad AS | Wholesale & retail | 2006 |
| Tni-Drift AS | Hospitality | 2024 |
| Tni-Eiendomsinvest AS | Real estate | 2024 |
| Tni-Holding AS | Real estate | 2024 |
| To-Foto AS | Information & communication | 1971 |
| Tom Fossheim AS | Wholesale & retail | 2023 |
| Tommys Flytteservice AS | Transport & logistics | 2025 |
| Topcoat Ans | Arts & recreation | 2003 |
| Topp Treindustri AS | Manufacturing | 2023 |
| Toppskarven Holding AS | | 2024 |
| Toppsundet Havfiske AS | Hospitality | 2013 |
| Toppsundet Maskin & Transport AS | Transport & logistics | 2015 |
| Tor & Bjørns Autoservice AS | Wholesale & retail | 1986 |
| Torbjørns Catering AS | Hospitality | 2008 |
| Tore Hunds Gate 5 AS | Real estate | 2014 |
| Tore Hunds GT 7 AS | Real estate | 2013 |
| Tore Killi AS | Administrative & support | 2014 |
| Tore Mevik Holding AS | Financial services | 2015 |
| Torgeir Killi AS | Real estate | 2015 |
| Tors Møbler AS | Wholesale & retail | 1992 |