| 13 Eiendom AS | Real estate | 2020 |
| Alexander Elvheim AS | Agriculture & fishing | 2013 |
| Arne Og Gunnar Sagmoen Ans | Agriculture & fishing | 1997 |
| AS Gjødselservice | Transport & logistics | 1989 |
| Autosenteret Tretten AS | Wholesale & retail | 2012 |
| Bjørnstad Granholt Eiendom Ans | Real estate | 2002 |
| Brannvern Innlandet AS | Professional & scientific | 2019 |
| Brede Stalsberg AS | Transport & logistics | 1990 |
| Bygg & Boligservice AS | Construction | 2025 |
| Bådstø AS | Real estate | 1997 |
| Dale Gudbrands Trykkeri AS | Manufacturing | 1985 |
| DC Bygg Service AS | Construction | 2022 |
| Det Norske Vaffelstekeriet AS | Hospitality | 2013 |
| Diner 13 AS | Hospitality | 2024 |
| Drivedge AS | Professional & scientific | 2025 |
| Dual Skogservice Da | Agriculture & fishing | 2011 |
| Dulven Friluftsbarnehage SA | Education | 1991 |
| Eco Solutions AS | Wholesale & retail | 2017 |
| Eik Økonomi AS | Wholesale & retail | 2005 |
| Enkelt Utført AS | Manufacturing | 2022 |
| Envecon AS | Manufacturing | 2023 |
| Felleskjerningen Eiendom AS | Real estate | 2013 |
| Fjellglede AS | Administrative & support | 2019 |
| Fotograf 13 AS | Professional & scientific | 2021 |
| Fullbrakt AS | Manufacturing | 2017 |
| Furuhaugen Eiendomsselskap AS | Real estate | 1995 |
| Glomstad Gjestehus AS | Hospitality | 2014 |
| Godt Skodd AS | Agriculture & fishing | 2020 |
| GS Eie AS | | 2022 |
| Gudbrandsdal Betongteknikk AS | Construction | 2022 |
| Gudbrandsdal Leiekjøring Da | Administrative & support | 2026 |
| Gudbrandsdal Steinindustri AS | Mining & quarrying | 2013 |
| Gummi Tak Gruppa Da | Construction | 2007 |
| HKB Turbuss AS | Transport & logistics | 2014 |
| Holmsetervegen SA | Real estate | 1931 |
| Hong AS | Real estate | 2005 |
| Hong Samdrift Ans | Agriculture & fishing | 1998 |
| Hundbergslia Avløp Utbygging SA | Construction | 2025 |
| Jakobsen Da | Wholesale & retail | 2003 |
| Jakobsen Maskinsalg AS | Manufacturing | 2025 |
| Jan Kristian Engen AS | Construction | 2026 |
| Jat Eiendom AS | Real estate | 2014 |
| K-E.L Energi AS | Construction | 2019 |
| K.M.Olsen AS | Real estate | 2013 |
| Kongsvegen 1569 AS | Real estate | 2017 |
| Kraft Eiendom AS | Real estate | 2022 |
| Kristianstuen Byggeservice AS | Construction | 2006 |
| Laugen Eiendom AS | Real estate | 2013 |
| Mageli Camping Og Hytter AS | Hospitality | 2002 |
| Murer Jan Helge Mosveen AS | Construction | 2014 |
| Musdal Brøytelag AS | Construction | 2022 |
| Musdal Eiendom AS | Real estate | 2007 |
| Musdal Sagservice Da | Agriculture & fishing | 2007 |
| Musdal Samdrift Da | Agriculture & fishing | 2007 |
| Musdalsetervegen SA | Real estate | 2013 |
| Musdalsæter Drift AS | Administrative & support | 2025 |
| Musdalsæter Hyttegrend AS | Real estate | 2007 |
| Myhren Murhåndverk AS | Construction | 2015 |
| Nord-Tretten Jaktforvaltning SA | Arts & recreation | 1921 |
| Northwave Group AS | | 2025 |
| Odin Eiendom Holding | Real estate | 2010 |
| Odin Eiendomsselskap AS | Real estate | 2001 |
| Offigstad AS | | 2026 |
| Pinnoy AS | Professional & scientific | 2017 |
| Robocraft AS | Agriculture & fishing | 2022 |
| Roåker Hyttegrend AS | Real estate | 2019 |
| Roåker Utmarkslag SA | Administrative & support | 1995 |
| Roåker-Vegen SA | Real estate | 1934 |
| Shell Tretten Da | Wholesale & retail | 2005 |
| Skog & Bio AS | Agriculture & fishing | 2024 |
| Skrekkens Hus Forlag AS | Information & communication | 2026 |
| Solby Tegnestue AS | Professional & scientific | 2023 |
| Stalsberg Samdrift Da | Agriculture & fishing | 1996 |
| Stav Fysikalske Vet.Senter AS | Health & social care | 2022 |
| Stav Næringsbygg AS | Professional & scientific | 2008 |
| Stav Veterinærsenter AS | Professional & scientific | 1998 |
| Stavsplassen SA | Administrative & support | 1997 |
| Steffen Engeland Holding AS | | 2023 |
| Strangstad Gard Da | Agriculture & fishing | 2006 |
| Strangstadstuen Samdrift Da | Agriculture & fishing | 2003 |
| Sverre Gjefsen AS | Manufacturing | 2005 |
| Sør-Tretten Eiendom AS | Real estate | 2005 |
| Sør-Tretten Jakt- Og Fiskelag SA | Other services | 1921 |
| Sør-Tretten Samdrift Da | Agriculture & fishing | 2004 |
| Tandac AS | Wholesale & retail | 1998 |
| Thomas Lieng AS | Other services | 2015 |
| Thomas Lieng Holding AS | Other services | 2022 |
| Tore Hagen Maskin AS | Construction | 2016 |
| Trettcon AS | Other services | 2024 |
| Tretten Betongsaging AS | Construction | 2023 |
| Tretten Blikkenslager Og Rørlegger AS | Construction | 1993 |
| Tretten Byggservice AS | Construction | 2016 |
| Tretten Frisørsalong AS | Other services | 2007 |
| Tretten Innkjøpslag SA | Wholesale & retail | 1958 |
| Tretten Lagerutleie AS | Real estate | 2016 |
| Tretten Mat AS | Wholesale & retail | 2019 |
| Tretten Minipris AS | Wholesale & retail | 1989 |
| Tretten Tannlegesenter AS | Health & social care | 2020 |
| Trettenkro AS | Hospitality | 2014 |
| Vang Samdrift Da | Agriculture & fishing | 2003 |