| Loistopaljut Oy | Administrative & support | 2022 |
| Loma Oulanka Avoin yhtiö | Hospitality | 1999 |
| Loma-asuntojen huoltopalvelu Säkkinen & Tyni Ay | Administrative & support | 1989 |
| Look7up Oy | Hospitality | 2020 |
| LouhiVakka Oy | Arts & recreation | 2025 |
| Lumi Live Oy | Arts & recreation | 2015 |
| Lumiruka Oy, Rakentamispalvelut | Construction | 1995 |
| Lumo Resorts Oy | Administrative & support | 2025 |
| Lumoe Oy | Other services | 2025 |
| Luola-Aho Oy | Agriculture & fishing | 2026 |
| Lämsä Logistics Oy | Transport & logistics | 2023 |
| Lääkäripalvelut Raittinen Ky | Health & social care | 2000 |
| M HILTULA Oy | Professional & scientific | 2010 |
| MJM Holding Oy | Professional & scientific | 2019 |
| Mm-Pursi Ky | Hospitality | 1993 |
| MRT Holding Oy | Financial services | 2024 |
| MV Huolto ja korjaus Oy | Other services | 2025 |
| Maakaivuu Hannula Oy | Construction | 2021 |
| Maalausliike A. Viinikka Oy | Construction | 1990 |
| Maalausliike Korpua & kumpp. | Construction | 1993 |
| Maalausliike Taisto Seppänen Oy | Real estate | 1978 |
| Maanrakennus Lämsä Oy | Construction | 2019 |
| Maanselän Työpalvelut Oy | Administrative & support | 2020 |
| Maansiirto Y. Teeriniemi Kommandiittiyhtiö | Construction | 1976 |
| Maarakennus Vallioniemi Oy | Construction | 2024 |
| Maaritin Pirssi Ky | Transport & logistics | 2014 |
| Mainostoimisto Davas Oy | Professional & scientific | 2007 |
| Mainostoimisto Feenix Oy | Professional & scientific | 2001 |
| Majoituspalvelut Määttä Oy | Administrative & support | 2026 |
| Mamma & Napero Ky | Wholesale & retail | 1989 |
| Mari Kukka Henriikka Oy | Health & social care | 2023 |
| Matkailu- ja rakennuspalvelu Kari Kallunki Oy | Hospitality | 1996 |
| Matkajoki Camping Oy | Hospitality | 1991 |
| Matovaaran Autopalvelut Ky | Administrative & support | 2012 |
| Matti Siikaluoma Oy | Transport & logistics | 1979 |
| Mediapaja Pohjoinen Oy | Information & communication | 2018 |
| Medisilva Oy | Health & social care | 2020 |
| Meteno Oy | Education | 2007 |
| Metsolan Kiinteistöpalvelu Oy | Administrative & support | 2019 |
| Metsäluhta Oy | Agriculture & fishing | 2019 |
| Metsätyö Palosaaret Oy | Agriculture & fishing | 2018 |
| Metsäurakointi Ervasti Oy | Agriculture & fishing | 2001 |
| Miniq Ky | Wholesale & retail | 2014 |
| Moilaskone Oy | Construction | 2017 |
| Moisen Oy | Professional & scientific | 2024 |
| Monialapalvelut Maarit Nevala Oy | Administrative & support | 2013 |
| Mons Alta Oy | Professional & scientific | 2025 |
| Mummon Herkut Oy | Manufacturing | 2023 |
| Mustosen Seudun Vesiosuuskunta | Water & waste | 1981 |
| MyTrail Finland Oy | Administrative & support | 2025 |
| NFTaide Oy | Information & communication | 2023 |
| Naava Advisory Oy | Professional & scientific | 2026 |
| Naketec Oy | Construction | 2026 |
| Natural klinikka Oy | Health & social care | 2025 |
| Neluapp Oy | Professional & scientific | 2024 |
| Net-Veke avoin yhtiö | Agriculture & fishing | 2020 |
| Nevala I & J Oy | Agriculture & fishing | 2004 |
| Nevipex Oy | Financial services | 2021 |
| Nieticca Oy | Wholesale & retail | 2009 |
| Nilo Market Oy | Wholesale & retail | 2019 |
| Nilon Hiuspiste Ky | Other services | 1989 |
| Nilon Valinta ky | Wholesale & retail | 1986 |
| Niskalan Tila Oy | Agriculture & fishing | 2020 |
| Nissinjokimutka Oy | Construction | 1990 |
| Nopes Oy | Mining & quarrying | 2002 |
| Nordic EMC Finland Oy | Professional & scientific | 2019 |
| Nordic Holiday Services Ltd Oy | Administrative & support | 1999 |
| North Natura Oy | Administrative & support | 2023 |
| Northern Reindeer Oy | Other services | 2018 |
| Note Shot Oy | Information & communication | 2004 |
| Noxisfin Oy | Wholesale & retail | 2025 |
| Nummelan Maa ja Metsä Oy | Agriculture & fishing | 2024 |
| Nuohous & Ilmastointi Karjalainen Oy | Administrative & support | 1997 |
| Nuohous Kuusamo Oy | Administrative & support | 2003 |
| Nuoriso- ja luontomatkailukeskus Oivanki Oy | Hospitality | 2014 |
| OER MTB Oy | Information & communication | 2021 |
| OPK Capital Oy | Professional & scientific | 2022 |
| Osakeyhtiö Six AB | Manufacturing | 2023 |
| OTK Rakennuspalvelu Oy | Construction | 2008 |
| OY VASA Camp Ltd | Administrative & support | 2009 |
| Oijusluoma Oy | Construction | 2020 |
| OispaSiisti Oy | Administrative & support | 2025 |
| Oivangin Lomakartano Oy | Hospitality | 2016 |
| Ollilan Lomamajat Oy | Hospitality | 2021 |
| Ollinlahti Oy | Transport & logistics | 2025 |
| Onnelliset tähdet Oy | Administrative & support | 2025 |
| Onnen Pilke Oy | Administrative & support | 2012 |
| Onnitalot Oy | Professional & scientific | 2021 |
| Osteopatiaklinikka Simo Kurvinen Ky | Other services | 2010 |
| Osuuskunta Biowood | Agriculture & fishing | 1999 |
| Osuuskunta Savotta Kuusamo | Agriculture & fishing | 2000 |
| Oulangan Murske Avoin yhtiö | Mining & quarrying | 2021 |
| Oulangan Taika Oy | Administrative & support | 2022 |
| Oulun Kotiosoite Oy | Wholesale & retail | 1999 |
| Ouluntie 42 Kiinteistö Oy | Real estate | 1997 |
| Outlag Oy | Professional & scientific | 2025 |
| Oy Kuusamon Kämppä Ab | Real estate | 1976 |
| PPP-Köökki Oy | Hospitality | 2022 |
| PRIMAL-AOS Oy | Information & communication | 2025 |
| PTP Skogstransporter AB Filial I Finland | Transport & logistics | 2014 |