| Sondre Moen AS | Construction | 2020 |
| Sporty Outdoor AS | Wholesale & retail | 2024 |
| Stanarhaugen AS | Real estate | 2005 |
| Storlegda Skog Og Seter Ans | Agriculture & fishing | 2010 |
| Storm Performance AS | Hospitality | 2023 |
| Stormora AS | Construction | 2004 |
| Storvegen 18 AS | Real estate | 2019 |
| Storvegen 26 Ans | Real estate | 2006 |
| Stranda Panorama AS | Real estate | 2019 |
| Strandvold AS | Real estate | 2006 |
| Studio Håret Da | Other services | 2005 |
| Studio Slakteri Ans | Information & communication | 2022 |
| Støpa Viltstellområde SA | Agriculture & fishing | 1986 |
| Sundet Fotball AS | Arts & recreation | 2000 |
| Sune Gøran Bengtsson | Agriculture & fishing | 2000 |
| Svein Karlsmoen Transport AS | Transport & logistics | 2013 |
| Svingen Transport AS | Transport & logistics | 2023 |
| Sønsthagen Nedre AS | Real estate | 2019 |
| Sør-Østerdal Media AS | Information & communication | 1998 |
| T Lien Invest AS | Real estate | 2005 |
| T.M.C Invest AS | Real estate | 2015 |
| Talas Holding AS | Real estate | 2016 |
| Tannlegene I Trysil AS | Health & social care | 2020 |
| TDR Varmepumper AS | Construction | 2023 |
| Teamtrysil AS | Wholesale & retail | 2015 |
| Tekstilen Trysil AS | Wholesale & retail | 2008 |
| Tepas AS | Health & social care | 1971 |
| Tepas Industrier AS | Health & social care | 1992 |
| Tepas Kompetanse AS | Health & social care | 2017 |
| The Atmosphere AS | Wholesale & retail | 2021 |
| THT Terapi AS | Health & social care | 2016 |
| TK 26 Eiendom AS | Real estate | 2024 |
| Tobb Holding AS | Wholesale & retail | 2017 |
| Toms Utleie AS | Real estate | 2023 |
| Torgalnup AS | Real estate | 2016 |
| TPT Holding AS | Wholesale & retail | 2005 |
| Tretopphytter Trysil AS | Hospitality | 2018 |
| Trollhetta Innovation AS | Administrative & support | 2012 |
| Trudvanggata Eiendom AS | Real estate | 2022 |
| Truenorth Life AS | Hospitality | 2025 |
| Tryblikk AS | Construction | 1987 |
| Trybo AS | Real estate | 2005 |
| Trysil 1 AS | | 2023 |
| Trysil 860 AS | Construction | 2013 |
| Trysil Aktiv AS | Arts & recreation | 2022 |
| Trysil Alpine Eiendom AS | Real estate | 2022 |
| Trysil Alpine Lodge AS | Real estate | 2018 |
| Trysil Bil & Bilutleie AS | Wholesale & retail | 2024 |
| Trysil Bil & Motor Ans | Administrative & support | 2007 |
| Trysil Bilberging AS | Other services | 2000 |
| Trysil Blomsterforretning AS | Wholesale & retail | 2012 |
| Trysil Boligutvikling AS | Real estate | 2019 |
| Trysil Booking AS | Real estate | 2025 |
| Trysil Bryggeri AS | Manufacturing | 2015 |
| Trysil Bygg & Vaktmesterservice AS | Real estate | 2020 |
| Trysil Byggprodukter AS | Manufacturing | 1994 |
| Trysil Dyreklinikk AS | Professional & scientific | 2004 |
| Trysil Eiendom & Utleie AS | Real estate | 2025 |
| Trysil Eiendoms Partner AS | Real estate | 2010 |
| Trysil Elektro AS | Construction | 1999 |
| Trysil Elektroservice AS | Wholesale & retail | 1986 |
| Trysil Element AS | Manufacturing | 2018 |
| Trysil Energistasjon AS | Wholesale & retail | 2026 |
| Trysil Engerdal Transport Og Spedisjon SA | Real estate | 1986 |
| Trysil Entreprenør AS | Construction | 2018 |
| Trysil Event AS | Professional & scientific | 2017 |
| Trysil Fjellbooking AS | Administrative & support | 2017 |
| Trysil Fjellhandel AS | Wholesale & retail | 2014 |
| Trysil Fjernvarme AS | Energy | 2001 |
| Trysil Flis & Malersenter AS | Construction | 1997 |
| Trysil Freelance Ans | Wholesale & retail | 2007 |
| Trysil Fritidseiendom AS | Real estate | 2018 |
| Trysil Fysioterapi AS | Health & social care | 2006 |
| Trysil Graving Og Traktor AS | Agriculture & fishing | 2020 |
| Trysil Handelseiendom AS | Real estate | 2021 |
| Trysil Helse Hud & Spa AS | Other services | 2013 |
| Trysil Helse Og Trening AS | Arts & recreation | 2016 |
| Trysil Holding AS | | 2020 |
| Trysil Industribygg AS | Real estate | 2021 |
| Trysil Industrihus AS | Real estate | 1964 |
| Trysil Innovator AS | | 2005 |
| Trysil Invest AS | Real estate | 1996 |
| Trysil Kommune Holding AS | Financial services | 2006 |
| Trysil Kontor Og Data AS | Wholesale & retail | 2005 |
| Trysil Leiligheter Resort AS | Real estate | 2018 |
| Trysil Liftutleie AS | Administrative & support | 2016 |
| Trysil Løpet AS | Administrative & support | 2024 |
| Trysil Maskinutleie AS | Construction | 2017 |
| Trysil Mountain Restaurants AS | Hospitality | 2020 |
| Trysil Multirep AS | Manufacturing | 2014 |
| Trysil Mur Og Puss AS | Construction | 2000 |
| Trysil Næringsforum SA | Professional & scientific | 2021 |
| Trysil Park AS | Real estate | 2023 |
| Trysil Pizza AS | Hospitality | 2006 |
| Trysil Pizza Og Grill AS | Hospitality | 2020 |
| Trysil Private Omsorgstjeneste AS | Health & social care | 2009 |
| Trysil Prosjektinvest AS | Real estate | 1990 |
| Trysil Prosjektutvikling AS | Construction | 2019 |
| Trysil Pukkverk AS | Mining & quarrying | 2010 |
| Trysil Race Academy AS | Education | 2019 |