| 2DESIGN AS | Professional & scientific | 2019 |
| Aage Invest AS | | 2021 |
| Afka AS | Administrative & support | 2019 |
| Alminor AS | Manufacturing | 1996 |
| Alminor Eiendom AS | Real estate | 1988 |
| Alseth Engineering AS | Professional & scientific | 2018 |
| Amh Industriservice AS | Professional & scientific | 2021 |
| Amt Anlegg AS | Administrative & support | 2003 |
| Amt Entreprenør AS | Construction | 1989 |
| Austbygde Bakeri AS | Wholesale & retail | 1984 |
| Austbygde Interiør & Fargehandel AS | Wholesale & retail | 2013 |
| Bakka Eiendom AS | Real estate | 2000 |
| Beck Holding AS | | 2022 |
| BNH Holding AS | Real estate | 2016 |
| Briskeåe Drift AS | Real estate | 2012 |
| Brødrene Fossheim Transport AS | Construction | 1980 |
| Byggmester Olesrud AS | Construction | 2026 |
| Christoffersen AS | Professional & scientific | 2015 |
| Dalebutikken AS | Manufacturing | 2019 |
| DFB AS | Health & social care | 2022 |
| Ecoarc AS | Professional & scientific | 2013 |
| Eggerud Finans AS | Professional & scientific | 2005 |
| Entreprenør Og Reparasjonsservice AS | Manufacturing | 1993 |
| Fjellguten Aktiv AS | Education | 2012 |
| Fjelltroll AS | Construction | 2025 |
| Fossheim Hytteservice AS | Real estate | 2016 |
| Fossheim Maskin Og Tjenester AS | Construction | 2022 |
| Fossheim Vedservice Da | Agriculture & fishing | 2022 |
| Frisørkroken AS | Other services | 2023 |
| Gavlen Fjellhandel AS | Wholesale & retail | 2015 |
| Gold AS | Wholesale & retail | 2011 |
| Hallingporten Properties AS | Real estate | 2021 |
| Haugen Treindustri AS | Manufacturing | 1997 |
| Haukaas Elektro AS | Construction | 2020 |
| Haukaas Utvikling AS | Construction | 2020 |
| Helge Gunnar Luraas AS | Construction | 2005 |
| Hund Og Eier Da | Administrative & support | 2025 |
| Intersport Rjukan AS | Wholesale & retail | 1987 |
| J Entreprenør AS | Construction | 2018 |
| Jkng Holding AS | Financial services | 2015 |
| Jonatinn Høylandsfe AS | Agriculture & fishing | 2015 |
| Kjetil Bakkas Eftf AS | Real estate | 2000 |
| Klehb Holding AS | Real estate | 2005 |
| Kleivan Bygg & Maskin AS | Construction | 2016 |
| Kolbeinsrud AS | Wholesale & retail | 2023 |
| Lurås Transport AS | Transport & logistics | 1998 |
| Manudesign AS | Construction | 2026 |
| MM Transport Og Vedlikehold AS | Administrative & support | 2022 |
| NN Haugen Treindustri AS | Manufacturing | 2021 |
| Obm Consulting AS | Education | 2015 |
| Olesrud AS | Construction | 2018 |
| Olesrud Utvikling AS | Real estate | 2026 |
| PK Øverdal AS | Construction | 2023 |
| Rjukan 360 AS | Professional & scientific | 2011 |
| Rørlegger Bergan AS | Construction | 2022 |
| Sag Holding AS | Construction | 2005 |
| Sandviken Camping AS | Hospitality | 2005 |
| SJ Prosjekt AS | Professional & scientific | 2024 |
| Skirvedalen Fjellservice AS | Construction | 2020 |
| Skiseil AS | Wholesale & retail | 1997 |
| Skrindebakke AS | Wholesale & retail | 2000 |
| Skrindebakke Eiendom AS | Real estate | 2022 |
| Skrindebakke Hus Og Hyttebygg AS | Construction | 2020 |
| STB Bygg AS | Professional & scientific | 2011 |
| Steinsrud Maskin AS | Construction | 1998 |
| Strand Holding AS | Other services | 1989 |
| Subsea Services AS | Administrative & support | 1998 |
| Sud Hjeljord Da | Agriculture & fishing | 2025 |
| Telemark Eigedom AS | Wholesale & retail | 2015 |
| Tessungdalen Bensin SA | Wholesale & retail | 2009 |
| Tessungdalen Utmarkslag SA | Arts & recreation | 2013 |
| Tessungdalen/Sandsetdalen Beitelag | Agriculture & fishing | 1981 |
| Tindefjell Fjellgrend AS | Real estate | 2000 |
| Tinn Husky Omsorg AS | Health & social care | 2026 |
| Tinn Montessoriskole SA | Education | 2010 |
| Tinn Reinhjordselskap AS | Real estate | 1983 |
| Tinn Vikar AS | Education | 2018 |
| Tinnbygg Eiendom AS | Construction | 2005 |
| Tmi Salg AS | Wholesale & retail | 2023 |
| TT Salg & Service AS | Manufacturing | 2018 |
| Tømrer Edvardsen AS | Construction | 2020 |