| Kirvesmiespalvelu Saukkonen Oy | Construction | 2007 |
| Kituuttamo Oy | Professional & scientific | 2022 |
| Kivi-Group Oy | Construction | 2021 |
| Kivityö Miikkulainen Oy | Construction | 2026 |
| Klako Oy | Financial services | 2022 |
| Kodin Kattokumppanit Oy | Construction | 2016 |
| Koivu Invest Oy | Professional & scientific | 2021 |
| Kojopower Oy | Wholesale & retail | 2012 |
| Kokkoma Oy | Construction | 1990 |
| Kone ja Kaivu Matti Heikkinen Ky | Construction | 2001 |
| Konehovi Oy | Administrative & support | 1988 |
| Konetyö Heino & Peuranpää Oy | Construction | 2023 |
| Konsultointi Jarmo Hiltunen Oy | Professional & scientific | 2025 |
| Korsisaari Oy | Transport & logistics | 1979 |
| Korsisaari-Yhtymä, E. Korsisaari & Co Kommandiittiyhtiö | Professional & scientific | 1978 |
| Kortemaa Oy | Professional & scientific | 1995 |
| Koti- ja hoivapalvelu Hoitorinki Oy | Health & social care | 2014 |
| Kotinikkari JJ Lehto Oy | Construction | 2000 |
| Kristian Blom Oy | Transport & logistics | 2002 |
| Kruunuhaan Kauppahuone Oy | Real estate | 1997 |
| Kuikkalan Marjat Oy | Agriculture & fishing | 2025 |
| Kuljetus Janne Tiljander Oy | Transport & logistics | 2010 |
| Kuljetus Pekka Rintala Oy | Transport & logistics | 1997 |
| Kuljetus Riiheläinen Oy | Transport & logistics | 2017 |
| Kuljetusliike Eino Vasenius Ky | Transport & logistics | 1987 |
| Kuljetusliike Hyvönen Ky | | 1986 |
| Kuljetusliike Patova Oy | Transport & logistics | 1983 |
| Kuljetusliike Pentti Vuoriheimo Oy | Transport & logistics | 1984 |
| Kuljetusliike T & J Rönkkö Oy | Transport & logistics | 1980 |
| Kulko Group Oy | Other services | 2010 |
| Kuorma-autokorjaamo Selekon Oy | Other services | 2014 |
| Kuusio Asiantuntijat Oy | Health & social care | 2024 |
| Kuva - Kirja Osakeyhtiö | Wholesale & retail | 1941 |
| Ky Optikko Veikko Paulin | Wholesale & retail | 1960 |
| Kärcher Oy | Wholesale & retail | 1983 |
| Kökkelin Hörppis Oy | Other services | 1992 |
| LP Telineet Oy | Construction | 2019 |
| LSN-Group Oy | Administrative & support | 2020 |
| LSP Consulting Oy | Professional & scientific | 2021 |
| LTZ Group Oy | Wholesale & retail | 2024 |
| LVI 25 Oy | Construction | 2025 |
| LVI-Insinööritoimisto HEUER Oy | Professional & scientific | 2013 |
| LVI-Väisänen Oy | Construction | 2008 |
| La-He-Invest Oy | Financial services | 1987 |
| LabStore Oy | Wholesale & retail | 2023 |
| Lagerhus Oy | Wholesale & retail | 2013 |
| Lahnuksen Vapaa-ajan Palvelut Oy | Real estate | 2004 |
| Lanium Oy | Information & communication | 1999 |
| Lattia Laatikainen Oy | Construction | 2020 |
| Lauris Trading Oy | Wholesale & retail | 1991 |
| Laxorm Oy | Wholesale & retail | 1990 |
| Leedi Oy | Other services | 2023 |
| Lets Camp Finland Oy | Administrative & support | 2023 |
| Li Yin Oy | Hospitality | 2021 |
| LindMed Oy | Wholesale & retail | 2024 |
| Living 24/7 Oy | Professional & scientific | 2022 |
| Living Types Oy | Professional & scientific | 1994 |
| Lommi Digital Oy | Information & communication | 2025 |
| Lorin Food Oy | Manufacturing | 2022 |
| Louhinta-Ässät Oy | Construction | 2004 |
| Lounas- ja tilausravintola MakuPata Oy | Hospitality | 2015 |
| Lumo Automotive Oy | Other services | 2022 |
| Lundahn Oy | Administrative & support | 2020 |
| Lynx Mountain Oy | Administrative & support | 2021 |
| M8 Auto Oy | Wholesale & retail | 2020 |
| MB Logistics & Services Oy | Other services | 2018 |
| MH-Urakointi Oy | Administrative & support | 2024 |
| MHN group Oy | Manufacturing | 2023 |
| MJM Handling Oy | Financial services | 2024 |
| MK Elementti Oy | Manufacturing | 2016 |
| MK-Louhinta Oy | Construction | 1989 |
| MS-Universal Oy | Wholesale & retail | 1999 |
| MT Tobacco Trade OY | Manufacturing | 2024 |
| MW Steel Oy | Other services | 2013 |
| Maalausliike Pertti Paajanen Oy | Construction | 1996 |
| Maalausliike Värisuora Oy | Construction | 2019 |
| Maanrakennus Kotisalo Oy | Construction | 2004 |
| Maansiirtoliike T. Leino Oy | Construction | 1975 |
| Maarakennus Jäntti Oy | Real estate | 2025 |
| Macrosoft Oy | Information & communication | 1989 |
| Mainostoimisto Taittomo Ky | Professional & scientific | 2013 |
| Majapohja Invest Oy | Real estate | 1989 |
| Makes Haulier Oy | Transport & logistics | 2019 |
| Malinranta Oy | Professional & scientific | 2022 |
| Man-yhtiöt Oy | Wholesale & retail | 2022 |
| Manmar Oy | Construction | 2023 |
| Maxodin Ky | Construction | 2004 |
| MecaCon Oy | Professional & scientific | 2016 |
| Medi-Lance Oy | Health & social care | 2005 |
| Medi10 Oy | Wholesale & retail | 2006 |
| MegaMoments Production Oy | Information & communication | 2023 |
| Mental Finland Oy | Arts & recreation | 2025 |
| Mertec Oy | Information & communication | 1989 |
| Mertenruususet Oy | Other services | 2023 |
| Mestarikone Laaksonen Oy | Wholesale & retail | 1992 |
| Metsänomistajapalvelu J-P Vapaniemi Oy | Agriculture & fishing | 2005 |
| Miika & Carita Oy | Wholesale & retail | 2016 |
| Miilunkorpi Oy | Real estate | 2013 |
| Min lycka oy | Real estate | 2023 |
| Miner Oy Kaivoksela | Hospitality | 2023 |