| Seso Holding AS | Real estate | 2019 |
| Shredyard AS | Wholesale & retail | 2025 |
| Silje Solheim AS | | 2026 |
| Silver Aqua Marine AS | Wholesale & retail | 2019 |
| Siv Janne Holding AS | | 2020 |
| SJK Holding AS | | 2024 |
| Sjurba Consult AS | Information & communication | 2024 |
| Sjøsiden Farge AS | Wholesale & retail | 2020 |
| SK Næring AS | Real estate | 2021 |
| Skaardalsmo Fuel Consulting AS | Professional & scientific | 2014 |
| Skarheim Invest AS | Financial services | 2015 |
| Skifer Eiendom AS | Real estate | 2012 |
| Skjelstad Holding AS | | 2014 |
| Skjelstadmark Grunneierlag SA | Real estate | 1979 |
| Skjelstadmark Snittelag Da | Agriculture & fishing | 2022 |
| Sklinna Holding AS | Real estate | 2020 |
| Sklinna Invest AS | Real estate | 2020 |
| Skogan/Granviken/Schønberg Da | Real estate | 2016 |
| Skoinvest Alp AS | Wholesale & retail | 1975 |
| Skotnes Bygg AS | Construction | 2005 |
| Skotnes Holding AS | Construction | 2005 |
| Skotnes Likviditet AS | Construction | 2019 |
| Skotnes Prosjekter AS | Professional & scientific | 2020 |
| Skrallans AS | Transport & logistics | 2021 |
| Skrallans Bil AS | Administrative & support | 2023 |
| Skulbørstad Holding AS | Education | 2021 |
| Skurdalsporten AS | Real estate | 2006 |
| Sliper Eiendom AS | Real estate | 2025 |
| Smart Agri Park AS | Professional & scientific | 2025 |
| Smart Mobility Norway AS | Professional & scientific | 2017 |
| Smartheater AS | Professional & scientific | 2022 |
| Smedveien 7 AS | Real estate | 2021 |
| Småge Drift Stjørdal AS | Construction | 2022 |
| Snoro Invest AS | Real estate | 2007 |
| Snurr Stjørdal AS | Manufacturing | 2024 |
| Soja Invest AS | | 2023 |
| Sola Parkering AS | Transport & logistics | 2009 |
| Solhaug Skipselektro AS | Wholesale & retail | 1979 |
| Sonate AS | Real estate | 2005 |
| Sonate Eiendom AS | Real estate | 2001 |
| Sonifish AS | Professional & scientific | 2025 |
| Soodabe AS | Other services | 2022 |
| Sorn Holding AS | Real estate | 2013 |
| Sorte Holding AS | Real estate | 2013 |
| Sortun Industri AS | | 2020 |
| Sortun Invest AS | Financial services | 2005 |
| SORZE4 AS | Wholesale & retail | 2010 |
| Sparegrisen AS | | 2005 |
| Spennarmering AS | Construction | 1988 |
| Spgg AS | Hospitality | 2024 |
| Spinafysio AS | Health & social care | 2025 |
| Spiss Invest AS | Real estate | 2005 |
| Sport 1 Stjørdal AS | Wholesale & retail | 2017 |
| Sportsfiskesenteret AS | Wholesale & retail | 2019 |
| SS Kapital AS | Professional & scientific | 2024 |
| Stall Elvira SA | Agriculture & fishing | 2009 |
| Stand Up Trondheim AS | Arts & recreation | 2014 |
| Stasjon Pizza & Grill AS | Hospitality | 2017 |
| Stasjonstomten AS | Real estate | 2015 |
| Steindalen AS | Mining & quarrying | 2014 |
| Steinsli Holding AS | | 2025 |
| Steinvik Bygg AS | Construction | 2011 |
| Steinvik Holding AS | Construction | 2010 |
| Steinvik Utleie AS | Real estate | 2015 |
| Steinvik-Eiendom AS | Real estate | 2011 |
| Stenborg AS | Financial services | 2005 |
| Stian Grindheim Holding AS | | 2022 |
| Stines Invest AS | | 2022 |
| Stiro Holding AS | Real estate | 2013 |
| Stisa AS | | 2021 |
| Stjernen Sølv AS | Manufacturing | 2026 |
| Stjørdal Autohandel AS | Wholesale & retail | 1984 |
| Stjørdal Autosalg AS | Wholesale & retail | 2004 |
| Stjørdal Barnehage SA | Education | 1994 |
| Stjørdal Bil AS | Wholesale & retail | 2017 |
| Stjørdal Bilglass AS | Other services | 2008 |
| Stjørdal Bilhandel AS | Wholesale & retail | 2025 |
| Stjørdal Bilklargjøring AS | Other services | 2025 |
| Stjørdal Bilpleie Ali AS | Other services | 2026 |
| Stjørdal Bilpleie Da | Other services | 2006 |
| Stjørdal Bilvask AS | Other services | 2016 |
| Stjørdal Boligutvikling AS | Real estate | 2009 |
| Stjørdal Bygdeservice SA | Administrative & support | 2003 |
| Stjørdal Byggutvikling AS | Real estate | 2004 |
| Stjørdal Eiendomsmegling AS | Real estate | 2018 |
| Stjørdal Eiendomsutvikling AS | Real estate | 2001 |
| Stjørdal Elektro AS | Construction | 2026 |
| Stjørdal Forsikringssenter AS | Financial services | 2021 |
| Stjørdal Garn AS | Wholesale & retail | 2017 |
| Stjørdal Hotel Da | Hospitality | 2003 |
| Stjørdal Intermaten AS | Wholesale & retail | 2021 |
| Stjørdal Invest AS | Real estate | 2016 |
| Stjørdal Kamelutleie AS | Real estate | 2014 |
| Stjørdal Kulturutvikling AS | Real estate | 2009 |
| Stjørdal Legesenter AS | Health & social care | 2005 |
| Stjørdal Lyd Ans | Arts & recreation | 1996 |
| Stjørdal Lyd Da | Arts & recreation | 1999 |
| Stjørdal Maskindrift AS | Construction | 2024 |
| Stjørdal Motor Og Fritid Da | Wholesale & retail | 2001 |
| Stjørdal Multiservice AS | Construction | 2024 |