| Kaos Oy | Wholesale & retail | 2023 |
| Kaovh Oy | Professional & scientific | 2004 |
| Kapaway Oy | Administrative & support | 2021 |
| Kapecon Oy | Professional & scientific | 2018 |
| Kaptas Oy | Manufacturing | 2007 |
| Kapuhili Oy | Professional & scientific | 2016 |
| Kapvest Oy | Financial services | 1987 |
| Karaplan Oy | Financial services | 1998 |
| Karhunoja Tech Oy | Construction | 2022 |
| Kari Media Group Oy | Professional & scientific | 1999 |
| Kari Papinoja Oy | Manufacturing | 1989 |
| Kari Rintala Ky | Wholesale & retail | 1986 |
| Karilex Oy | Financial services | 1999 |
| Karimeri Oy | Real estate | 1989 |
| Karina-Asunnot Oy | Real estate | 2000 |
| Karitma Oy | Wholesale & retail | 2002 |
| Karkaisu Oy | Manufacturing | 2021 |
| Karki Rani Oy | Hospitality | 2026 |
| Karlmax Ky | Manufacturing | 2009 |
| Karma Development Oy | Financial services | 2023 |
| Karma Studio Oy | Education | 2012 |
| Karmat Ky Kari Rintala | Administrative & support | 1991 |
| Karo Healthcare Oy | Wholesale & retail | 2018 |
| Karporator Oy | Professional & scientific | 2007 |
| Karrintalo Oy | Financial services | 1989 |
| Karrintalon Lämpö Oy | Administrative & support | 1969 |
| Karsticon Oy | Professional & scientific | 2022 |
| Kashlinkken Productions Oy Ab | Hospitality | 2022 |
| Kasikate Oy | Construction | 2008 |
| Kasimax Oy | Professional & scientific | 2000 |
| Kasisataa Oy | Construction | 2012 |
| Kaskaad Oy | Professional & scientific | 2013 |
| Kasken Kodit Oy | Real estate | 2007 |
| Kaskimax Oy | Hospitality | 2001 |
| Kasku Oy | Financial services | 2002 |
| Kasnet Oy | Professional & scientific | 2009 |
| Kasper August Art Oy | Arts & recreation | 2022 |
| Kassamies Oy | Wholesale & retail | 2013 |
| Kasvattajarahasto Ky | Financial services | 2015 |
| Kasvuneuvos Oy | Professional & scientific | 2025 |
| Kataiito Oy | Financial services | 2019 |
| Kataja Investments Oy | Financial services | 2013 |
| Katariina Aura Oy | Other services | 2022 |
| Katariina Raike Oy | Education | 2020 |
| Katarina Holding Oy | Professional & scientific | 2023 |
| Kateax oy | Financial services | 2026 |
| Katevirta | Wholesale & retail | 2020 |
| Katrak Oy | Construction | 1990 |
| Katri Luukkonen Oy | Health & social care | 2006 |
| Katri Wood & Co Oy | Wholesale & retail | 1996 |
| KattoClean Oy | Real estate | 2022 |
| Kattokeskus Varsinais-Suomi Oy | Construction | 2017 |
| Kattokonsultointi Jari Mustikkamaa Oy | Professional & scientific | 2017 |
| Kattosepät Oy | Construction | 2001 |
| Kattotyö Jari Virta Oy | Construction | 2016 |
| Kaukinen Invest Oy | Financial services | 2016 |
| Kauko Kaskinen Ky | Wholesale & retail | 1993 |
| Kauko Tuominen Ky | Hospitality | 1988 |
| Kaulakko Oy | Construction | 2022 |
| Kaumame Oy | Real estate | 2020 |
| Kauneushoitola Mandarine Oy | Other services | 2008 |
| Kauneushoitola Meloni Oy | Other services | 2011 |
| Kauneushoitola Sweet Beauty Oy | Other services | 2020 |
| Kauniit ja Ruskeat Oy | Other services | 1993 |
| Kaunis Suomi Oy | Wholesale & retail | 2011 |
| Kaunismaa Capital Oy | Financial services | 2017 |
| Kauniston Koneistamo Oy | Manufacturing | 1986 |
| Kaupallistajat Suomi Oy | Professional & scientific | 2015 |
| Kauppahuone A B M Oy | Wholesale & retail | 2008 |
| Kauppahuone Eurotie Oy | Construction | 1992 |
| Kauppahuone Finnhansa Oy | Wholesale & retail | 2006 |
| Kauppahuone Ka-Ja-Ar-To Oy | Wholesale & retail | 2006 |
| Kauppahuone Lux Oy | Wholesale & retail | 1981 |
| Kauppahuone Portnoj Oy | Wholesale & retail | 2010 |
| Kauppahuone Stenroos Oy | Professional & scientific | 2004 |
| KauppakasiTech avoin yhtiö | Manufacturing | 2021 |
| Kauppakeskus Hansa GP Oy | Financial services | 2000 |
| Kauppakeskus Hansa Ky | Real estate | 2000 |
| Kauppapuutarha Risto J. Järvinen Oy | Agriculture & fishing | 1979 |
| Kaupparobo Avoin yhtiö | Manufacturing | 2021 |
| Kauppatorin Lääkintävoimistelu Ky | Health & social care | 1975 |
| Kauppatorin Tilikeskus Oy | Professional & scientific | 1991 |
| Kauppi Quality Oy | Professional & scientific | 2024 |
| Kauppilan koti ja piha Oy | Construction | 2007 |
| Kauttuan Ykköstori Ky | Real estate | 1996 |
| Kave Oy | Information & communication | 1981 |
| Kaveh Oy | Wholesale & retail | 2025 |
| Kavionjälki Oy | Arts & recreation | 2024 |
| KeMed Sport Oy | Health & social care | 2014 |
| KeTo Kiinteistöt Oy | Real estate | 2020 |
| Kebab Ahmad avoin yhtiö | Hospitality | 2024 |
| Kebab box & Broastie Oy | Hospitality | 2025 |
| Kehityspalvelu Turku Oy | Real estate | 2023 |
| Kehitysyhtiö Itämeri Oy | Professional & scientific | 2016 |
| Kehon kutsu Oy | Education | 2025 |
| Kehonetti Oy | Health & social care | 2020 |
| Keijo Laine seur. Oy | Wholesale & retail | 1971 |
| Keijulaakso Oy | Education | 2017 |
| Keilalahti Marina Oy | Financial services | 2001 |
| Keilapojat Oy | Hospitality | 2016 |