| Kattokollit Oy | Construction | 2017 |
| Kattokolmio Oy | Construction | 2026 |
| Kattokunto Oy | Construction | 2020 |
| Kattomestarit Oy Rakennusyhtymä | Construction | 2005 |
| Kattovelho Oy | Construction | 2025 |
| Katve Works Oy | Construction | 2023 |
| Katztudio Oy | Arts & recreation | 2021 |
| Kauhavan musiikki Lagerstedt & Co | Wholesale & retail | 1979 |
| Kaukajärven Opiskelijatalo Oy | Real estate | 1985 |
| Kaukajärven parturi-kampaamo Ky | Other services | 2016 |
| Kaukajärviosuuskunta | Administrative & support | 1965 |
| Kauko Leppänen Oy | Construction | 2019 |
| Kaukokiito Henkilöstö Oy | Administrative & support | 2008 |
| Kaukonen Capital Oy | Professional & scientific | 2023 |
| Kauneuden Harmonia Oy | Professional & scientific | 2019 |
| Kauneuden ja hyvänolon hoitola Beauty Drop Oy | Other services | 2003 |
| Kauneushoitola Kasvot Oy | Other services | 2017 |
| Kauneushoitola Meli Oy | Other services | 2024 |
| Kauneushoitola Paklaamo avoin yhtiö | Other services | 1996 |
| Kaunispään Tervas 1 Oy | Real estate | 2026 |
| Kaunispään Tervas 2 Oy | Real estate | 2026 |
| Kaunispään Tervas 3 Oy | Real estate | 2026 |
| Kauppahallin Kotilounas Oy | Hospitality | 2010 |
| Kauppahallin Kotiruoka Oy | Hospitality | 2001 |
| Kauppahallin Pyörykkäbaari Oy | Hospitality | 2017 |
| Kauppahallin Ravintola Oy | Hospitality | 2004 |
| Kauppahuone Hakanpää Oy | Wholesale & retail | 2021 |
| Kauppahuone Harju Oy | Wholesale & retail | 1984 |
| Kauppahuone Hyvärinen Oy | Real estate | 1957 |
| Kauppahuone Rytkönen Oy | Wholesale & retail | 2023 |
| Kauppahuone Välimäki Oy | Professional & scientific | 2023 |
| Kauppakadun Rauta Oy | Wholesale & retail | 2021 |
| Kauppaseuran Kiinteistö Oy | Real estate | 1957 |
| KauppiTwins Oy | Other services | 2021 |
| Kaupunkien parkkipalvelu Oy | Administrative & support | 2010 |
| Kaupunkiravintolat Oy | Hospitality | 2009 |
| Kaurakangas Oy | Professional & scientific | 2006 |
| Kausa Consulting Oy | Professional & scientific | 2013 |
| Kausarit Oy | Administrative & support | 2026 |
| Kaussi Oy | Professional & scientific | 1983 |
| Kautto & Konstig Oy | Professional & scientific | 2020 |
| Kavire Agency avoin yhtiö | Arts & recreation | 2017 |
| Keep Off Media OY | Information & communication | 2019 |
| KeepLoop Oy | Manufacturing | 2011 |
| Kehittämispalvelut Auvinen Oy | Professional & scientific | 2013 |
| Kehitysosakeyhtiö Arvo | Professional & scientific | 2020 |
| Kehollinen Oy | Real estate | 2021 |
| Kehotaiteet MH Oy | Other services | 2024 |
| Kehrä Consulting Oy | Professional & scientific | 2024 |
| Kehys-Meka Avoin yhtiö | Wholesale & retail | 2004 |
| Kehyskodit Oy | Real estate | 2025 |
| Kehysliike Malkki Oy | Wholesale & retail | 2004 |
| Kehystyspalvelu Nyström Oy | Wholesale & retail | 1989 |
| Keijo Numminen Oy | Financial services | 2013 |
| Keijon Fiilunki Oy | Other services | 2022 |
| Keikkanet Oy | Information & communication | 2025 |
| Keinus Oy | Information & communication | 2022 |
| Keinänen Group Oy | Wholesale & retail | 2002 |
| Keittiökauppa Kylväjä Oy | Wholesale & retail | 2023 |
| Keiturin Sote Oy | Health & social care | 2015 |
| Kekao Oy | Education | 2024 |
| Keke Armstrong Oy | Education | 2006 |
| Kekkeruusi & Co. Oy | Hospitality | 2025 |
| Kekäläinen Solutions Oy | Professional & scientific | 2025 |
| Kellohuolto Tommi Alanen Ky | Other services | 2016 |
| Kellotupa Oy | Wholesale & retail | 2025 |
| KeloTwin Oy | Information & communication | 2020 |
| Kelomentti Oy | Financial services | 1997 |
| Kelpo Invest Oy | Financial services | 2014 |
| Kelpo Yritys Oy | Administrative & support | 2025 |
| Keltainen Kolmio Ky | Other services | 1993 |
| Keltainen Ovi Oy | Professional & scientific | 2010 |
| Kemion Oy | Professional & scientific | 2013 |
| Kemppiset Oy | Professional & scientific | 1992 |
| Kenin reseptit Oy | Hospitality | 2021 |
| Kenkärepo Oy | Wholesale & retail | 1988 |
| Kenkätarha Kommandiittiyhtiö | Wholesale & retail | 1975 |
| Kenttäkivi Oy | Construction | 1972 |
| Keramiikkaosuuskunta Liekki | Wholesale & retail | 2023 |
| Kerdiili oy | Professional & scientific | 2025 |
| Kerkon Oy | Financial services | 2021 |
| Kero Capital Oy | Professional & scientific | 2022 |
| Kerpua Oy | Professional & scientific | 2021 |
| Kerpua Solutions Oy | Professional & scientific | 2014 |
| Kerpua Wear Solutions Oy | Professional & scientific | 2020 |
| Kertoja Oy | Health & social care | 2013 |
| Keräyspaperi Kari Toivonen Oy | Wholesale & retail | 1995 |
| Keräystoimisto Jouko Elo Oy | Professional & scientific | 1992 |
| Kesfin Oy | Other services | 2000 |
| Keski-Himos Oy | Construction | 1992 |
| Keski-Pukkila Oy | Health & social care | 2025 |
| Keski-Suomen Maximini Ky | Hospitality | 1991 |
| Keski-Suomen Taloudellinen Neuvontakeskus Oy | Real estate | 1989 |
| Keskinäinen Kiinteistö Oy Ahertajat | Real estate | 1983 |
| Keskinäinen Vakuutusyhtiö Turva | Financial services | 1934 |
| Keskipakovalu Oy | Manufacturing | 1956 |
| Keskuojankulma Oy | Real estate | 2011 |
| Keslem Oy | Professional & scientific | 2013 |
| Kesto Case Oy | Wholesale & retail | 2021 |
| Kestomuovi Oy | Manufacturing | 2007 |