| Mehis avoin yhtiö | Agriculture & fishing | 2004 |
| Mekamonex ky | Professional & scientific | 1990 |
| Menette Oy | Professional & scientific | 2026 |
| Merkai Oy | Information & communication | 2008 |
| Merrylor Oy | Financial services | 2023 |
| MetForce Oy | Manufacturing | 2018 |
| Metatavu Oy | Information & communication | 2016 |
| Metrom Ky | Other services | 2020 |
| Metsä Hiekkaniemi Oy | Agriculture & fishing | 2025 |
| Metsä Tommola Ky | Agriculture & fishing | 1986 |
| Metsä-Kiesit Oy | Agriculture & fishing | 1996 |
| Metsä-Pöysä Oy | Agriculture & fishing | 2013 |
| Metsäkone Hokkanen Oy | Agriculture & fishing | 1992 |
| Metsäosuuskunta Tammi | Agriculture & fishing | 2016 |
| Metsäsairila Oy | Water & waste | 2006 |
| Metsätyö Hänninen Oy | Agriculture & fishing | 2016 |
| Metsätyö Pasi Leinonen Oy | Agriculture & fishing | 2024 |
| Metsätyöt Vlog Oy | Manufacturing | 2020 |
| Metsäunelmat Oy | Agriculture & fishing | 2019 |
| Mevisor Oy | Professional & scientific | 2008 |
| Mexita Oy | Wholesale & retail | 2018 |
| Mi-sukka Oy | Manufacturing | 1989 |
| MiR Invest Oy | Financial services | 2013 |
| MiX Studio Oy | Education | 2022 |
| Miemri Ky | Arts & recreation | 2012 |
| MikLam Trading Oy | Wholesale & retail | 2020 |
| Mika Luukkonen Oy | Information & communication | 1994 |
| Mika Pulkkinen Ky | Transport & logistics | 1996 |
| Mikalo Oy | Real estate | 1972 |
| Mikamar Ky | Real estate | 2010 |
| Mikkeli Siivotaan Oy | Administrative & support | 2013 |
| Mikkelin Arkistotalo Oy - Arkivhuset i S:t Michel Ab | Real estate | 1990 |
| Mikkelin Asumisoikeus Oy | Real estate | 1991 |
| Mikkelin Autokuljetus Oy | Construction | 1948 |
| Mikkelin Autopuhdistus Ky | Other services | 1996 |
| Mikkelin Autotyö Oy | Other services | 1972 |
| Mikkelin Burger Oy | Hospitality | 2005 |
| Mikkelin Car Clean Oy | Other services | 2015 |
| Mikkelin Energia Oy | Energy | 1995 |
| Mikkelin Floora Oy | Real estate | 2013 |
| Mikkelin Fysikaalinen Hoitolaitos Ky | Health & social care | 1975 |
| Mikkelin HL Kotikaluste Oy | Manufacturing | 1997 |
| Mikkelin Hinauskuljetus Oy | Transport & logistics | 1992 |
| Mikkelin Hitsauspalvelu Oy | Manufacturing | 2008 |
| Mikkelin Invataksi Ky | Transport & logistics | 1986 |
| Mikkelin Isännöintipalvelut Oy | Real estate | 2024 |
| Mikkelin Joretuote Oy | Manufacturing | 1983 |
| Mikkelin Juvantie Oy | Financial services | 1982 |
| Mikkelin Kassa- ja AV-palvelu Ky | Other services | 1983 |
| Mikkelin Kate-Team Ky | Construction | 1989 |
| Mikkelin Keittiömyynti Oy | Wholesale & retail | 2012 |
| Mikkelin Kierrätyskeskus Oy | Wholesale & retail | 2026 |
| Mikkelin Kilpi ja Kaiverrus Ky | Wholesale & retail | 1991 |
| Mikkelin Kiviladonta Oy | Construction | 2020 |
| Mikkelin Kiviveistämö Oy | Manufacturing | 2014 |
| Mikkelin Koiraurheilukeskus Oy | Real estate | 2013 |
| Mikkelin Kone- ja Tarvike Kommandiittiyhtiö | Wholesale & retail | 1992 |
| Mikkelin Konsultointi ja Sijoitus Ky | Professional & scientific | 2009 |
| Mikkelin Konttorikone ja Kalusto Vilma Inoranta Kommandiittiyhtiö | Wholesale & retail | 1975 |
| Mikkelin Kopiopiste Oy | Administrative & support | 2012 |
| Mikkelin Laattacenter Oy | Wholesale & retail | 2005 |
| Mikkelin Lasiasennus Oy | Manufacturing | 1979 |
| Mikkelin Laskenta Oy | Professional & scientific | 1994 |
| Mikkelin Liikekiinteistöt Oy | Real estate | 1990 |
| Mikkelin Liikuntahallit Oy | Arts & recreation | 2024 |
| Mikkelin Liikuntakeskus Oy | Arts & recreation | 1996 |
| Mikkelin Lukko ja Avain Oy | Financial services | 1980 |
| Mikkelin Lukkosepät Oy | Wholesale & retail | 2000 |
| Mikkelin Lämpöhuolto Oy | Wholesale & retail | 2000 |
| Mikkelin MSS Oy | Real estate | 2000 |
| Mikkelin Matkailu Oy | Public administration | 1964 |
| Mikkelin Mediaali Oy | Professional & scientific | 1998 |
| Mikkelin Mikaeli Oy | Arts & recreation | 2006 |
| Mikkelin Monipalvelu Oy | Wholesale & retail | 2018 |
| Mikkelin Motopaja Avoin yhtiö | Other services | 1993 |
| Mikkelin Nostajat Oy | Construction | 1975 |
| Mikkelin Nuohoustoimi Ky | Administrative & support | 1985 |
| Mikkelin OMT-Keskus Ky | Health & social care | 2011 |
| Mikkelin OMT-Palvelu Ky | Health & social care | 1983 |
| Mikkelin Omakoti-Rakentajat Ky | Construction | 2008 |
| Mikkelin Omaksi Oy | Transport & logistics | 2017 |
| Mikkelin Oppilaitoskiinteistöt Oy | Real estate | 2012 |
| Mikkelin Palvelutaksit Oy | Transport & logistics | 1996 |
| Mikkelin Piikkaus- ja Porauspalvelu Janne Paasonen Ky | Construction | 1986 |
| Mikkelin Puhelinosuuskunta | Information & communication | 1924 |
| Mikkelin Päänsärkypoliklinikka Oy | Health & social care | 1992 |
| Mikkelin Rakennus ja Elementti Oy | Construction | 1994 |
| Mikkelin Rakennus ja Saneeraus Oy | Construction | 2011 |
| Mikkelin Rauhaniemen LPA-yhtiö Oy | Real estate | 1997 |
| Mikkelin Ravirata Oy | Arts & recreation | 1974 |
| Mikkelin Rengaspiste Oy | Wholesale & retail | 2014 |
| Mikkelin Romu Oy | Water & waste | 2015 |
| Mikkelin Sairaalaparkki Oy | Transport & logistics | 2016 |
| Mikkelin Saja Oy | Real estate | 1990 |
| Mikkelin Seudun Liikennekoulu Ky | Education | 1988 |
| Mikkelin Sisustuspalvelu Ky | Construction | 2006 |
| Mikkelin Sportman Oy | Wholesale & retail | 2000 |
| Mikkelin Sukkulat Oy | Other services | 2024 |
| Mikkelin Sähköhuolto Oy | Construction | 2014 |
| Mikkelin TI-halli Oy | Real estate | 2025 |