| KM-Sijoitus Oy | Real estate | 2017 |
| KMN-Palvelut Oy | Real estate | 2011 |
| KMS-Movies Oy | Information & communication | 1996 |
| KOKO-Keittiö Oy | Wholesale & retail | 2016 |
| KOMIA Flow Oy | Arts & recreation | 2017 |
| Koneurakointi O.Katila Ky | Construction | 2004 |
| KORA Installations Oy | Construction | 2009 |
| KOY Seinäjoen Linnea-Kiinteistöt | Real estate | 2016 |
| KOY Seinäjoen Rasmus-Kiinteistöt | Real estate | 2013 |
| KR Motors Ky | Other services | 2014 |
| KS HeliCom Oy | Wholesale & retail | 2013 |
| KT Kolarikorjaus Oy | Other services | 2009 |
| KVS Valaistussuunnittelu Oy | Construction | 2013 |
| Kaamos Kauneus Oy | Other services | 2024 |
| Kaapeliauto Oy | Wholesale & retail | 2022 |
| Kaarto Service Oy | Other services | 2018 |
| Kahvila-Konditoria Pikku-Paussi Oy | Hospitality | 1992 |
| Kaija Heittola Ky | Professional & scientific | 2016 |
| Kainuun Teräsmiehet Oy | Manufacturing | 2012 |
| Kairapuro Oy | Construction | 2008 |
| Kaivukaksikko Ky | Construction | 1989 |
| Kajapek Oy | Financial services | 2017 |
| Kajastus Rent Ky | Administrative & support | 2021 |
| Kajo Group Oy | Administrative & support | 2025 |
| Kajo Mökit Oy | Hospitality | 2021 |
| Kajo Yhtiöt Oy | Wholesale & retail | 2021 |
| KakkuKeidas Oy | Manufacturing | 2020 |
| Kaksi Vaakaa Oy | Administrative & support | 2018 |
| Kaksosflikat Oy | Arts & recreation | 2023 |
| Kaluste-Valtonen Ky | Manufacturing | 1983 |
| Kalustetalo Kalle Perälä Oy | Wholesale & retail | 1977 |
| Kalve 016 OY | Wholesale & retail | 2023 |
| Kamuko Oy | Other services | 2016 |
| Kanawa Oy | Construction | 2020 |
| Kanervo Logistic Oy | Transport & logistics | 2011 |
| Kangas Wood Trading Oy | Wholesale & retail | 1995 |
| Kangas-Investing Oy | Real estate | 1990 |
| Kangasalan Liikunta- ja hyvinvointikeskus Oy | Real estate | 2021 |
| Kangaskeskus Ky | Wholesale & retail | 2010 |
| Kankaanpää Racing Club Ky | Other services | 2025 |
| Kankia Oy | Professional & scientific | 2019 |
| Kanssi Rakennus Oy | Construction | 2017 |
| Kapcon Oy | Professional & scientific | 2010 |
| Kapsian Oy | Other services | 2021 |
| Kardisan Oy | Health & social care | 2007 |
| Karhunkaira Oy | Hospitality | 2000 |
| Kari Kuokka Oy | Wholesale & retail | 2006 |
| Kariikka Oy | Wholesale & retail | 2007 |
| Karitan Capital Oy | Financial services | 2019 |
| Karkkikauppa Nami ja Nekku Oy | Wholesale & retail | 2020 |
| Karstulan Murske Ky | | 1985 |
| Kartano Consulting Oy | Professional & scientific | 2025 |
| Kartar Oy | Hospitality | 2023 |
| Karvian kivi ja korjaus oy | Professional & scientific | 2013 |
| Karvonen Invest Oy | Administrative & support | 2014 |
| KaseyOS Oy | Information & communication | 2024 |
| Katoka Invest Oy | Financial services | 2025 |
| Kattilakoski Oy | Financial services | 1983 |
| Kauhavan Alariitti Oy | Real estate | 1992 |
| Kauhavan Hammaslääkärikeskus Oy | Health & social care | 1995 |
| Kauhavan Vaihtomööpeli Oy | Wholesale & retail | 1990 |
| Kaukomaalaus Oy | Construction | 1989 |
| Kauneus Gym Oy | Other services | 2025 |
| Kauneus- ja hyvinvointipalvelut Sinun Salonkisi Ky | Other services | 2012 |
| Kauneus- ja terveyshoitola Susanna Aro Oy | Other services | 2012 |
| Kauneushoitola Sariela Oy | Other services | 2015 |
| Kaunisneva Oy | Real estate | 1996 |
| Kaunisto-Yhtiöt Oy | Construction | 1979 |
| Kauppahuone Malmivaara Ky | Wholesale & retail | 2009 |
| Kauppahuone Pehkonen Oy | Wholesale & retail | 2011 |
| Kauppakadun Auto Ky | Wholesale & retail | 1978 |
| Kauppapaikka Pavla Oy | Wholesale & retail | 1993 |
| Kaura Group Oy | Financial services | 2026 |
| Kausalan Kaukolämpö Oy | Energy | 2023 |
| Kehitystehdas Oy | Professional & scientific | 2020 |
| Kehoklinikka CTNS Oy | Health & social care | 2025 |
| Kehosto Oy | Health & social care | 2021 |
| Kehystämö Liljala Oy | Wholesale & retail | 2021 |
| Keittiöset Oy | Wholesale & retail | 2021 |
| Keizo Oy | Information & communication | 2021 |
| Kelokakkonen Kommandiittiyhtiö | Real estate | 1982 |
| Kempire Entertainment Oy | Information & communication | 2024 |
| Kenkoan Oy | Health & social care | 2025 |
| Kesas Invest Oy | Financial services | 2016 |
| Kesas-Yhtiöt Oy | Real estate | 2011 |
| Kescon Ky | Professional & scientific | 2005 |
| Keska Oy | Real estate | 1998 |
| Keskinen Invest Ky | Real estate | 1995 |
| Keskustaksi Oy | Transport & logistics | 1975 |
| Kestävä Koti Ky | Construction | 2010 |
| Ketomäki Kiinteistöt Oy | Real estate | 2025 |
| Ketomäki Yhtymä Oy | Agriculture & fishing | 2024 |
| Keuruun Keilakeskus Oy | Arts & recreation | 2010 |
| Keviz Shield Oy | Financial services | 2025 |
| Kiertoa Oy | Information & communication | 2015 |
| Kiinteistö Oy Akkis | Real estate | 1996 |
| Kiinteistö Oy Ala-Jyrä | Real estate | 1986 |
| Kiinteistö Oy Buustinnankulma | Real estate | 2024 |
| Kiinteistö Oy H & H | Real estate | 2018 |
| Kiinteistö Oy Heikkilän Hallit | Real estate | 2009 |