| Munna AS | Wholesale & retail | 2007 |
| Mur & Bo AS | Construction | 2010 |
| Mur Og Anlegg AS | Construction | 2017 |
| Myceleriet AS | Agriculture & fishing | 2021 |
| Myk Hygge AS | Wholesale & retail | 2021 |
| Må Invest AS | Wholesale & retail | 2008 |
| Mæhle AS | Transport & logistics | 2021 |
| Mælia/Losliveien SA | Real estate | 1955 |
| Møllen Restaurant Og Pizzeria AS | Hospitality | 1998 |
| Mønstr AS | Professional & scientific | 2021 |
| Naess & Lihaug AS | Hospitality | 2021 |
| Nerviken Eiendom AS | Real estate | 1996 |
| Nestuggu Oppdal AS | Real estate | 2017 |
| Netor Holding AS | Real estate | 2015 |
| Nikla AS | Financial services | 2011 |
| Nonshøa AS | Professional & scientific | 2011 |
| Norbeck & Strand Minimaskiner Da | Administrative & support | 2001 |
| Norbeck Ent AS | Construction | 2009 |
| Norbeck Entreprenør AS | Construction | 2024 |
| Nordvia AS | Wholesale & retail | 2018 |
| Norgeshus Oppdal Bygg AS | Construction | 2016 |
| Norheim Natursten AS | Real estate | 2010 |
| Norheim Natursten Eiendom AS | Real estate | 2012 |
| Norheim Natursten Skifer AS | Construction | 2010 |
| Norheim Natursten Vest AS | Construction | 2013 |
| Norrøn Laft Oppdal AS | Construction | 2006 |
| Norway Rock AS | Arts & recreation | 2007 |
| Numerik AS | Transport & logistics | 2012 |
| Ny Fritid AS | Real estate | 2016 |
| Nye Bjerkaker Eiendom AS | Real estate | 2022 |
| Nyveien Eiendom AS | Real estate | 2005 |
| Nyvold Eiendom AS | Real estate | 2023 |
| Nyvold Installasjon AS | Construction | 1990 |
| O. Johnsen AS | Construction | 2018 |
| O23 Consult AS | Professional & scientific | 2011 |
| Odd Fellow Huset Sletvold AS | Real estate | 2013 |
| Oer Invest AS | | 1991 |
| Okla AS | Real estate | 2006 |
| Olav Solberg AS | Construction | 1986 |
| Olendt AS | Construction | 2022 |
| Onkel Skrue Holding AS | Real estate | 2005 |
| Oorts AS | Professional & scientific | 2022 |
| Opalis Nord AS | Information & communication | 2026 |
| Opdals Sparebank | Financial services | 1856 |
| Opp Fryseri AS | Transport & logistics | 2021 |
| Opp Media Ans | Manufacturing | 2001 |
| Opp Og Opdalingen AS | Information & communication | 2002 |
| Oppcamp AS | Hospitality | 2021 |
| Oppconsult AS | Professional & scientific | 2014 |
| Oppdal & Rennebu Begravelsesbyrå AS | Other services | 2003 |
| Oppdal 3D-PRINT Da | Professional & scientific | 2026 |
| Oppdal Alpin Idrettsanlegg AS | Arts & recreation | 2021 |
| Oppdal Auto AS | Transport & logistics | 2013 |
| Oppdal Betong AS | Manufacturing | 1989 |
| Oppdal Bilberging AS | Transport & logistics | 2001 |
| Oppdal Bilberging Eiendom AS | Real estate | 2020 |
| Oppdal Bilskade AS | Other services | 2015 |
| Oppdal Bo Og Fritid Ans | Health & social care | 2005 |
| Oppdal Bowling AS | Arts & recreation | 2011 |
| Oppdal Bygdeservice SA | Administrative & support | 2015 |
| Oppdal Bygg Eiendom AS | Real estate | 2016 |
| Oppdal Bygg Holding AS | Construction | 2022 |
| Oppdal Bygg Utvikling AS | Real estate | 2007 |
| Oppdal Dyreklinikk AS | Professional & scientific | 2004 |
| Oppdal Eiendomsmegling AS | Real estate | 2014 |
| Oppdal Event AS | Hospitality | 2011 |
| Oppdal Fjellservice AS | Other services | 2023 |
| Oppdal Fysioterapi AS | Health & social care | 2020 |
| Oppdal Garasjeanlegg AS | Real estate | 2019 |
| Oppdal Golfsimulator AS | Arts & recreation | 2021 |
| Oppdal Graving Og Transport AS | Construction | 2013 |
| Oppdal Helsekost AS | Wholesale & retail | 2026 |
| Oppdal Hotelldrift AS | Hospitality | 2009 |
| Oppdal Hotellinvest AS | Real estate | 2009 |
| Oppdal Hudklinikk AS | Other services | 2023 |
| Oppdal Interiør & Arkitektur AS | Professional & scientific | 2023 |
| Oppdal Landbrukstjenester SA | Agriculture & fishing | 1982 |
| Oppdal Maskinkompani AS | Construction | 1969 |
| Oppdal Mat AS | Wholesale & retail | 1998 |
| Oppdal Minilager AS | Real estate | 2024 |
| Oppdal Motell AS | Hospitality | 1998 |
| Oppdal Næringsutvikling AS | Real estate | 2004 |
| Oppdal Og Omegn Eiendomsmegling AS | Real estate | 2025 |
| Oppdal Pizza AS | Hospitality | 2020 |
| Oppdal Restaurantdrift AS | Hospitality | 2001 |
| Oppdal Skiheiser AS | Arts & recreation | 1984 |
| Oppdal Spekemat AS | Manufacturing | 2009 |
| Oppdal Sport Invest AS | Wholesale & retail | 2005 |
| Oppdal Sten AS | Mining & quarrying | 1993 |
| Oppdal Sten Eiendom AS | Real estate | 1998 |
| Oppdal Synsenter AS | Wholesale & retail | 2022 |
| Oppdal Taxi SA | Transport & logistics | 1965 |
| Oppdal Thermotransport Ans | Transport & logistics | 2001 |
| Oppdal Treningssenter AS | Arts & recreation | 1995 |
| Oppdal Turisthotell AS | Real estate | 2000 |
| Oppdal Turisthotell Drift AS | Hospitality | 2017 |
| Oppdal Uteliv AS | Hospitality | 2007 |
| Oppdal VVS A/S | Construction | 1988 |
| Oppdal-Bil AS | Wholesale & retail | 2012 |
| Oppdalsegg AS | Agriculture & fishing | 2012 |