| Steirotoppen AS | Hospitality | 2004 |
| Sterico AS | | 2018 |
| Stian Grønbeck AS | | 2019 |
| Store Nordlys Restaurant AS | Hospitality | 2020 |
| Stories of Wonder AS | Professional & scientific | 2021 |
| Storneset Eiendom AS | Real estate | 2018 |
| Stortinden AS | Real estate | 2005 |
| Strand Panorama AS | Real estate | 1995 |
| Strand Utmarkslag SA | Other services | 2012 |
| Strand Vannverk SA | Water & waste | 1964 |
| Strandgata 17 AS | Real estate | 2006 |
| Strandgata 30 Eiendom Sortland AS | Real estate | 2005 |
| Strandgata 31 Sortland AS | Real estate | 2019 |
| Strandgata 34 Sortland AS | Hospitality | 2023 |
| Strandgata 40 AS | Real estate | 2020 |
| Strandgata 44 AS | Real estate | 2017 |
| Strandgata Blå AS | Real estate | 2008 |
| Studio 1 Frisør Sortland AS | Other services | 2018 |
| Stylist-X AS | Other services | 2009 |
| Støversteen Invest AS | Real estate | 2007 |
| Sundbø Produksjoner AS | Professional & scientific | 2021 |
| Suortà Eiendom AS | Real estate | 2018 |
| Suortà Invest AS | Real estate | 2018 |
| Svarholtveien 6 AS | Real estate | 2015 |
| Svartehavet II Da | Real estate | 2006 |
| Svein Vollen AS | Agriculture & fishing | 2006 |
| Sveis & Maskinteknikk AS | Manufacturing | 1998 |
| Sveis & Maskinteknikk Eiendom AS | Manufacturing | 1993 |
| Sylvias Blomster Hjørne AS | Wholesale & retail | 2025 |
| Skipsaksjeselskapet Sirius | Transport & logistics | 1988 |
| Søndre Holand Vannverk SA | Water & waste | 2014 |
| Sørfjorden Skogsveiforening Ba | Construction | 2004 |
| Tab Vista Holding AS | | 2025 |
| Takstteam Nord AS | Professional & scientific | 2016 |
| Takstteam Vesterålen AS | Professional & scientific | 2012 |
| Tannlege Elde AS | Health & social care | 2023 |
| Tannlege Emilie R. Hanssen AS | Health & social care | 2023 |
| Tannlege Mette Bergh AS | Health & social care | 2024 |
| Tare AS | Professional & scientific | 2006 |
| Tare Invest AS | Professional & scientific | 2017 |
| TBH Trockeenbau Hopf | Construction | 2008 |
| Teisten AS | Agriculture & fishing | 2016 |
| Teistevoll Trucking AS | Transport & logistics | 2025 |
| Teknisk Bureau Sortland AS | Other services | 1984 |
| Teknobingo Sortland AS | Arts & recreation | 2004 |
| Terje Steiro Eiendom AS | Real estate | 1999 |
| The Lady Ans | Hospitality | 2020 |
| The Pharma Factory AS | Professional & scientific | 2015 |
| The Storyteller AS | Real estate | 2021 |
| Thomtof AS | | 2020 |
| Thor Johanssen AS | Real estate | 1963 |
| Tide Marine AS | Wholesale & retail | 2000 |
| Tindstinden AS | Professional & scientific | 2005 |
| Tindstinden Holding AS | | 2023 |
| Tingvoll Eiendom AS | Manufacturing | 1994 |
| Tingvoll Holding AS | | 2018 |
| Tip Top Design AS | Other services | 1998 |
| TJ Gruppen AS | Administrative & support | 2026 |
| TJ Konsult AS | Construction | 2023 |
| Tjelta Vinduspuss AS | Administrative & support | 2020 |
| Tjønnvollen Småbåtforening | Arts & recreation | 1991 |
| TKN Eiendom AS | Real estate | 2022 |
| TMS Invest AS | Real estate | 2024 |
| TNB Sortland AS | Wholesale & retail | 2004 |
| Tobiassen Invest AS | Financial services | 2016 |
| Toen AS | Financial services | 2005 |
| Tomforde-Bautenschutz | Construction | 2009 |
| Tonje Toften AS | | 2020 |
| Topsitt Toften AS | Real estate | 2005 |
| Torggata 10A AS | Real estate | 2019 |
| Torleif Steiro AS | Wholesale & retail | 1991 |
| Torleif Steiro Holding AS | Wholesale & retail | 2000 |
| Tortob Consult AS | Professional & scientific | 2019 |
| Totinden AS | Financial services | 2008 |
| Trafikkskolen Vesterålen AS | Education | 2022 |
| Transportmannen AS | Transport & logistics | 2016 |
| Tre-Bo AS | Construction | 1978 |
| Tretinden AS | Real estate | 2008 |
| Trio Eiendom AS | Real estate | 2001 |
| TRL Invest AS | | 2026 |
| Trockenbau Mario Linss | Construction | 2008 |
| Trollura AS | Professional & scientific | 2021 |
| Trollura Eiendom AS | Real estate | 2021 |
| Trond Geir Invest AS | Manufacturing | 2010 |
| True Holding AS | Hospitality | 2023 |
| True Vesterålen Hotel AS | Hospitality | 2023 |
| Truls Hammer AS | Transport & logistics | 2021 |
| Trygve Hansen AS | Real estate | 1987 |
| TV SENTRAL SERVICE OG RALLARENS GAVEHJØRNE Laila og Frank Antonsen | Other services | 1983 |
| Tvedt Optikk AS | Wholesale & retail | 2015 |
| Tømrer Jan Kåre Nyrud AS | Construction | 2011 |
| Tømrer Leon Bolstad AS | Construction | 2012 |
| Tømrer Tommy Johansen AS | Construction | 2017 |
| Ue Maskin & Utleie AS | Construction | 2024 |
| Uhre Invest AS | Real estate | 2021 |
| Umwelttechnik Und Brunnenbau Wöltjen GmbH | Construction | 2008 |
| Unipro Nord AS | Agriculture & fishing | 1992 |
| Utsøkt Norge AS | Wholesale & retail | 2021 |
| V. Eide Holding AS | | 2018 |
| Vann Og Varmeteknikk AS | Construction | 2013 |