| Stjørdal Optikk AS | Wholesale & retail | 2008 |
| Stjørdal Parkering AS | Transport & logistics | 2015 |
| Stjørdal Rørleggerservice AS | Construction | 2003 |
| Stjørdal Sjøtransport AS | Transport & logistics | 2006 |
| Stjørdal Tannhelsesenter AS | Health & social care | 2008 |
| Stjørdal Utbygging AS | Real estate | 2006 |
| Stjørdal Utleiemaskiner AS | Real estate | 1989 |
| Stjørdal Utmarkslag SA | Arts & recreation | 1957 |
| Stjørdal Utvikling AS | Real estate | 2010 |
| Stjørdal Utvikling Delte Selskaper AS | | 2025 |
| Stjørdal Utvikling Holding AS | Real estate | 2020 |
| Stjørdal Øye AS | Health & social care | 2026 |
| Stjørdalens Blad Og Malvik-Bladet AS | Information & communication | 1989 |
| Stjørdalsnett AS | Information & communication | 1988 |
| Stjørdalsnytt.No AS | | 2021 |
| Stoffhuset AS | Wholesale & retail | 2021 |
| Stokkan Eiendom AS | Financial services | 2012 |
| Stokke Gård Adventure AS | Real estate | 2020 |
| Stokmoen Fysioterapi Da | Health & social care | 2002 |
| Stokmoveien 8 AS | Real estate | 2003 |
| Stolt Leveranse AS | Transport & logistics | 2025 |
| Storlien Hytter AS | Real estate | 2003 |
| Strandveien Auto Stjørdal AS | Other services | 1990 |
| Streetfood Company AS | Hospitality | 2024 |
| Strelitzia AS | Real estate | 2025 |
| Stræte Betongpumping AS | Real estate | 1997 |
| Stræte Holding AS | | 2026 |
| Styrk Eiendom AS | Real estate | 2023 |
| Styrk Reklame AS | Professional & scientific | 2022 |
| Sunchaser Drift AS | Other services | 2013 |
| Sundbotten Eiendom AS | Real estate | 2003 |
| Superia Cars AS | Wholesale & retail | 2025 |
| Sutterø Eiendom AS | Real estate | 2021 |
| Sutterø Næringspark AS | Real estate | 2025 |
| Sutterøy Nord AS | Real estate | 2013 |
| Sutterøygata 121 AS | Real estate | 1997 |
| Sutterøygata 7 AS | Real estate | 2024 |
| Suwo Invest AS | Real estate | 2010 |
| Svartflesa AS | Wholesale & retail | 2016 |
| Sved Kapital AS | | 2025 |
| Svedtech AS | Professional & scientific | 2024 |
| Svera Holding AS | | 2026 |
| Sverre AS | Administrative & support | 2017 |
| SW Consulting AS | Information & communication | 2017 |
| Swamp AS | Financial services | 2018 |
| Sylsjøveien AS | Real estate | 2015 |
| Synlig Optikk AS | Wholesale & retail | 2011 |
| Systudio Solbær AS | Other services | 2026 |
| Sæthers Conditori Ans | Wholesale & retail | 1991 |
| Sæthers Conditori AS | Wholesale & retail | 2006 |
| Sætnan Miljødeponi AS | Mining & quarrying | 2026 |
| Søberg Invest AS | Real estate | 1986 |
| Sølv & Gullsmia AS | Manufacturing | 1994 |
| Søndre Gate 6 AS | Real estate | 2015 |
| Søndre Tannhelse AS | Health & social care | 2010 |
| Søndregate Eiendom AS | Real estate | 2004 |
| Søndregt 2 AS | Real estate | 1990 |
| Sørgård Transport AS | Transport & logistics | 2023 |
| Ta Pro Consulting AS | Professional & scientific | 2000 |
| Tabularis AS | Professional & scientific | 2021 |
| Taka Bygg AS | Professional & scientific | 2014 |
| Takst, Mur Og Ingeniørtjenester AS | Professional & scientific | 2026 |
| Taktila AS | Professional & scientific | 2016 |
| Taktila International AS | Professional & scientific | 2022 |
| Tandem Reklame AS | Professional & scientific | 2012 |
| Tangen Engineering AS | Professional & scientific | 2015 |
| Tangen Innovation AS | Professional & scientific | 2014 |
| Tangen Legekontor AS | Health & social care | 1992 |
| Tangen Næringsbygg AS | Real estate | 1998 |
| Tangskogen Eiendom AS | Real estate | 2014 |
| Tannlege Erik Henriksson AS | Health & social care | 2005 |
| Tannlege Ertsås AS | Health & social care | 2022 |
| Tannlegene Dullum AS | Health & social care | 2026 |
| Tannlegene Dullum AS | Health & social care | 2009 |
| Taraxacum Barnehage Stjørdal AS | Education | 2022 |
| Team GK Mat Ans | Hospitality | 1992 |
| Techconsulting Nuf | Professional & scientific | 2017 |
| Techpro Service AS | Manufacturing | 2023 |
| Techzone AS | Information & communication | 2026 |
| Teglgata 5 AS | Real estate | 2013 |
| Teglgata 8 AS | Real estate | 1990 |
| Teigens Project AS | Arts & recreation | 2004 |
| Teky AS | Professional & scientific | 2015 |
| Tensio AS | Energy | 2019 |
| Tepo AS | Wholesale & retail | 1987 |
| Terje Kilen AS | Arts & recreation | 2013 |
| Terrasonde AS | Professional & scientific | 2011 |
| Tess Invest AS | Financial services | 2016 |
| The Carpenters Da | Construction | 2008 |
| TIKTOKKEBABK1 Da | Hospitality | 2026 |
| Tine Hedsten AS | Wholesale & retail | 2015 |
| Tito-Eiendom AS | Real estate | 2022 |
| TJ & LMG Eiendom 6 AS | Real estate | 2019 |
| TJ & LMG Holding AS | Real estate | 2018 |
| Tjrådgivning AS | Professional & scientific | 2025 |
| Tk-Eiendom AS | | 2018 |
| TMT Raaen AS | Transport & logistics | 1989 |
| Tobiaz AS | Wholesale & retail | 2012 |
| Tod AS | Professional & scientific | 2020 |
| Tode AS | Real estate | 2004 |