| Loma-Kainuu Oy | Administrative & support | 1997 |
| Lomafi Oy | Real estate | 2022 |
| Lomps Oy | Information & communication | 2022 |
| Loowa Oy | Professional & scientific | 2024 |
| Louhirinne Oy | Wholesale & retail | 2020 |
| Luonnollisesti Oulujärvi Oy | Administrative & support | 2006 |
| Luontaistuote Vitaminna Oy | Wholesale & retail | 1998 |
| Luontokuva Pekka Helo Ky | Arts & recreation | 1982 |
| LähiTapiola Kainuu - Koillismaa Keskinäinen Vakuutusyhtiö | Financial services | 1945 |
| Lähiruokatori Kaisun Kahveri Oy | Wholesale & retail | 2014 |
| Lämpö Oy Käenpolku 2-4 | Energy | 1974 |
| MAVIMA Oy | Real estate | 2019 |
| MEA Group Oy | Professional & scientific | 2020 |
| MG Innovaatiot Oy | Manufacturing | 1994 |
| MH Solutions Oy | Professional & scientific | 2026 |
| MJK Transport Oy | Transport & logistics | 1997 |
| MK Clinic Oy | Other services | 2016 |
| MKP Huusko Oy | Agriculture & fishing | 2019 |
| MSK Service Oy | Real estate | 2021 |
| Maalausliike E. Mononen Ky | Construction | 1991 |
| Maalausliike Värihovi Oy | Construction | 2020 |
| Maanrakennus J.T.J. Väisänen Oy | Administrative & support | 1979 |
| Maanrakennus MAP-Kone Oy | Construction | 2014 |
| Maansiirto Junttila Oy | Construction | 1977 |
| Maarakennus Jan Kone Oy | Construction | 1995 |
| Maemi Oy | Wholesale & retail | 2019 |
| Maija Karjalainen Ky | Hospitality | 1984 |
| Mainos21 Oy | Professional & scientific | 2010 |
| Mainoskolmio Oy | Professional & scientific | 2012 |
| Mainoslähde Oy | Professional & scientific | 2007 |
| Mainospalvelu M Oy | Professional & scientific | 2008 |
| Mainostoimisto Närhi Oy | Professional & scientific | 1997 |
| Mainuan Turve Oy | Mining & quarrying | 1982 |
| Mainuan vesiosuuskunta | Water & waste | 2012 |
| Maisemakallio Oy | Real estate | 2024 |
| Make It Easy Oy | Wholesale & retail | 2021 |
| Maken Vuokraus & Finanssit Oy | Administrative & support | 2012 |
| Mappiapp Oy | Information & communication | 2025 |
| Mari Ja Tuukka Huusko avoin yhtiö | Wholesale & retail | 2015 |
| Marko Karppinen inspirium Oy | Health & social care | 2013 |
| Martti Jaatinen Oy | Information & communication | 2003 |
| Mask Realms Oy | Real estate | 2024 |
| Massiwe Oy | Construction | 2022 |
| Matti Kanniainen Oy | Transport & logistics | 1981 |
| Mattoasennus Karjalainen Oy | Construction | 2018 |
| Maximum Welding Oy | Construction | 2022 |
| Medi-Lehtis Oy | Wholesale & retail | 2024 |
| Medikierukka Oy | Health & social care | 2007 |
| Meoline Oy | Professional & scientific | 2015 |
| Meri-Lapin Huolto oy | Other services | 2022 |
| Mestarimaalaus Seppänen & Toikka Oy | Construction | 1991 |
| Metallikoneistamo E. Moilanen Ky | Manufacturing | 1983 |
| Meteriot Oy | Information & communication | 2021 |
| Metsä- ja koneyhtymä Haarapuro Oy | Agriculture & fishing | 2022 |
| Metsäkonetyö Lappalainen Ky | Agriculture & fishing | 1999 |
| Miilu Games Oy | Information & communication | 2019 |
| Mikeon Oy | Professional & scientific | 2005 |
| Millery Oy | Manufacturing | 2019 |
| Mintun Leipomukset Oy | Manufacturing | 2026 |
| Mittaturkis E. Kauppinen & U. Moilanen | | 1990 |
| MoBa Sol Oy | Hospitality | 2020 |
| Modulo Services Oy | Construction | 2020 |
| Monitra Production avoin yhtiö | Health & social care | 2021 |
| Mono Race Oy | Administrative & support | 2023 |
| Montessoripäiväkoti Kiva Paikka Oy | Education | 2005 |
| Mosari Oy | Manufacturing | 1994 |
| Moto Team Tauriainen Oy | Agriculture & fishing | 1995 |
| Mountain Productions Oy | Arts & recreation | 2023 |
| Mpi-Edustus Oy | Wholesale & retail | 2019 |
| Murtovoima Oy | Construction | 2019 |
| Musiikki Matti avoin yhtiö | Administrative & support | 1986 |
| Musiikki Sulus Raimo Kelho Kommandiittiyhtiö | | 1963 |
| Musiikki-Vuorela Ky | Arts & recreation | 1979 |
| Myllykoski Consulting Oy | Professional & scientific | 2022 |
| Myynninkasvattajat Oy | Wholesale & retail | 2023 |
| Myyntipalvelu J. Lukkari Ky. | Wholesale & retail | 2009 |
| Next Level Padel OY | Arts & recreation | 2021 |
| NK Välitys Oy | Other services | 2012 |
| Nakkilan Matkailu Oy | Arts & recreation | 2024 |
| Need More Bullets Oy | Information & communication | 2024 |
| Neliöfix Oy | Construction | 2024 |
| Nerve Oy | Wholesale & retail | 2016 |
| Ninnukka Ky | Wholesale & retail | 1985 |
| Nivalan Puskutyö Oy | Construction | 1995 |
| Nopeaa Digital Oy | Information & communication | 2025 |
| Nordavera Oy | Financial services | 2026 |
| Nordic R-Tec Oy | Wholesale & retail | 2021 |
| Nordrec Henkilöstöpalvelut Oy | Administrative & support | 2022 |
| Nordrec Mining Oy | Administrative & support | 2025 |
| Nordrec Pohjois-Savo Oy | Administrative & support | 2023 |
| Nordrec Rakennus Oy | Administrative & support | 2026 |
| Normaint Oy | Manufacturing | 2013 |
| Normal Invest Oy | Professional & scientific | 2015 |
| North Shore Oy | Real estate | 2026 |
| Northland Kiinteistöt Oy | Real estate | 2012 |
| Nuottijärvi Oy | Hospitality | 2018 |
| Nälkämaan pizza Avoin yhtiö | Hospitality | 2018 |
| O-Market Oy | Wholesale & retail | 2022 |
| OHLAS Consulting Oy | Construction | 2021 |
| OHLAS Group Oy | Construction | 2025 |