| Onkl K AS | Transport & logistics | 2024 |
| Ophuus AS | Transport & logistics | 2020 |
| Opplev Røros AS | Administrative & support | 2008 |
| Optimalisert AS | Information & communication | 2025 |
| Optimus AS | Health & social care | 1991 |
| Optimus Utvikling AS | Professional & scientific | 2026 |
| Optimus Vekst AS | Health & social care | 2026 |
| Orvos Beitelag SA | Agriculture & fishing | 1980 |
| Orvos Vannverk SA | Water & waste | 1938 |
| Osloveien 32 AS | Real estate | 2023 |
| Otnes Eiendom AS | Real estate | 2016 |
| Our Innovation AS | Professional & scientific | 2025 |
| Pakkhuset Ute Depot AS | Real estate | 2018 |
| Peder Hiortgata 6 AS | Real estate | 2020 |
| Pels Holding AS | Financial services | 2005 |
| Pikasu AS | | 2022 |
| PMH Holding AS | Other services | 2016 |
| Potteriet Røros AS | Manufacturing | 1997 |
| Pressit AS | Arts & recreation | 1998 |
| Pro Cosmetique AS | Health & social care | 2020 |
| Progress Consult AS | Professional & scientific | 1995 |
| Prøsch Veterinærservice AS | Professional & scientific | 1986 |
| Puma Holding AS | Financial services | 2013 |
| Parfymeriet AS | Real estate | 1988 |
| Påsken Fjøsdrift Da | Agriculture & fishing | 2006 |
| Påsken Gård Ans | Agriculture & fishing | 2004 |
| R.K. Betongpartner AS | Administrative & support | 2018 |
| Rauma Tweed Eiendom AS | Real estate | 2012 |
| RB-1 Holding AS | Manufacturing | 2021 |
| Reflekta AS | | 2009 |
| Reimersberget AS | Construction | 2005 |
| Ren Røros AS | Energy | 1976 |
| Ren Røros Batteri AS | Energy | 2026 |
| Ren Røros Digital AS | Information & communication | 2024 |
| Ren Røros Eiendom AS | Real estate | 2016 |
| Ren Røros El-Service AS | Construction | 2017 |
| Ren Røros Strøm AS | Energy | 2017 |
| Reneo AS | Professional & scientific | 2021 |
| RETENK-247 AS | Information & communication | 2025 |
| Riddervold Holding AS | Construction | 2021 |
| RM Bygg Aksje AS | Real estate | 2023 |
| RM Bygg AS | Real estate | 2005 |
| Rocket Sport AS | Wholesale & retail | 2025 |
| Roec Holding AS | Financial services | 2017 |
| Rør På Røros AS | Construction | 2002 |
| Rør På Røros Eiendom AS | Real estate | 2024 |
| Rørlegger Martin Bakke AS | Construction | 2020 |
| Rørlegger Ola Langmo AS | Construction | 2021 |
| Rørleggermester Kjell Aunmo AS | Construction | 2002 |
| Røros Auto AS | Other services | 1997 |
| Røros Bandasje AS | Wholesale & retail | 2002 |
| Røros Barnehage Ba | Education | 1989 |
| Røros Bilutleie AS | Administrative & support | 2018 |
| Røros Bryggeri Og Mineralvannfabrikk AS | Manufacturing | 2013 |
| Røros Burger & Beers AS | Hospitality | 2024 |
| Røros Bygg AS | Real estate | 2000 |
| Røros Chocolate AS | Manufacturing | 2025 |
| Røros Container Og Miljø AS | Water & waste | 2007 |
| Røros Dyreklinikk AS | Professional & scientific | 2012 |
| Røros Dyretransportservice AS | Transport & logistics | 2024 |
| Røros Dører Og Vinduer AS | Manufacturing | 1996 |
| Røros Elektrohandel AS | Wholesale & retail | 2015 |
| Røros Flyservice RRS AS | Transport & logistics | 2001 |
| Røros Folkehøgskole Eiendom AS | Real estate | 2019 |
| Røros Fritid AS | | 2005 |
| Røros Garn AS | Wholesale & retail | 2026 |
| Røros Gjensidige Heste- Og Kreaturforsikringsselskap | Financial services | 1885 |
| Røros Golfpark AS | Arts & recreation | 1997 |
| Røros Gym AS | Arts & recreation | 2015 |
| Røros Holding AS | | 2025 |
| Røros Hotell AS | Hospitality | 1986 |
| Røros Hotell Eiendom AS | Real estate | 1947 |
| Røros Indoor Golf AS | Arts & recreation | 2024 |
| Røros Invest AS | | 2010 |
| Røros Kobberverk AS | Real estate | 2011 |
| Røros Konserter AS | Arts & recreation | 2021 |
| Røros Kultur Og Konferansesenter AS | Administrative & support | 1986 |
| Røros Kunstformidling AS | Wholesale & retail | 2015 |
| Røros Malerservice AS | Construction | 2016 |
| Røros Malerservice Eiendom AS | Real estate | 2007 |
| Røros Mat Og Catering AS | Manufacturing | 2017 |
| Røros Metall Aksje AS | | 2023 |
| Røros Metall AS | Manufacturing | 2002 |
| Røros Metall Eiendom AS | Real estate | 1989 |
| Røros Metall Holding 1 AS | | 2005 |
| Røros Metall Holding 2 AS | Financial services | 2005 |
| Røros Møbler AS | Wholesale & retail | 2003 |
| Røros Og Omland Begravelsesbyrå AS | Other services | 2008 |
| Røros Opticon AS | Construction | 2013 |
| Røros Optikk AS | Wholesale & retail | 2005 |
| Røros Parfymeri & Mini AS | Other services | 2023 |
| Røros Parkering AS | Transport & logistics | 2001 |
| Røros Porten Eiendom AS | Real estate | 2000 |
| Røros Produkter AS | Manufacturing | 2008 |
| Røros Produkter Eiendom AS | Real estate | 2022 |
| Røros Rengjøringsbyrå AS | Administrative & support | 2012 |
| Røros Slakteri AS | Manufacturing | 1988 |
| Røros Solfilm Og Tuningservice Da | Other services | 2024 |
| Røros Stallen Da | Arts & recreation | 2025 |
| Røros Stasjon Pizza Og Grill AS | Hospitality | 2026 |