| Kirvestyö Huikko oy | Construction | 2022 |
| Kisa-Fysio Oy | Health & social care | 1987 |
| Kisas Oy | Real estate | 2016 |
| Kisko Express Oy | Transport & logistics | 2020 |
| Kissakahvila Mirri Oy | Hospitality | 2024 |
| Kitusalo Oy | Professional & scientific | 2023 |
| Kiuru Path Oy | Health & social care | 2026 |
| Kivi ja laatta Jukka Ky | Construction | 2012 |
| Kivi-Kerttu Oy | Construction | 2015 |
| KiviKoski Horizon Group Oy | Health & social care | 2025 |
| Kivikankare Oy | Other services | 2009 |
| Kivikartio Oy | Real estate | 1994 |
| Kiviliike Velj. Alander Oy | Manufacturing | 2007 |
| Kivivesi Oy | Financial services | 1994 |
| Kivo Oy | Wholesale & retail | 2018 |
| Klimek Electric Oy | Construction | 2020 |
| Klo Design Oy | Professional & scientific | 2006 |
| Kloffa Group Oy | Manufacturing | 2019 |
| Klonk Oy | Hospitality | 1999 |
| Klook Oy | Education | 2025 |
| Klopal Oy | Information & communication | 2012 |
| Kloppi Creative Agency Oy | Professional & scientific | 2013 |
| Klymät Consulting Oy | Wholesale & retail | 2018 |
| Klyro Consulting Oy | Information & communication | 2026 |
| Klåvus Oy | Agriculture & fishing | 2016 |
| Klåvus Tukku Oy | Wholesale & retail | 2015 |
| Knowledge Creation Oy | Financial services | 2016 |
| Knuderm Oy | Health & social care | 2024 |
| Knuutin Puutarha Oy | Agriculture & fishing | 2005 |
| KoCos Shop Oy | Wholesale & retail | 2018 |
| Kode Labs Oy | Information & communication | 2019 |
| Kodin Ompelukone Oy | Wholesale & retail | 1984 |
| Kodinkoneklinikka veljekset Stenroos Oy | Other services | 2016 |
| Kogar Oy | Real estate | 2016 |
| Kognitiivinen psykoterapiapalvelu S. Venho Oy | Health & social care | 2023 |
| Kohde Pharma Oy | Professional & scientific | 2025 |
| Kohokohta Oy | Transport & logistics | 2017 |
| Kohtuuttomat energiasopimukset Oy | Professional & scientific | 2024 |
| Koillis-Lapin Tilipalvelu Kommandiittiyhtiö | Professional & scientific | 1977 |
| Koira-Kissa Rehu Oy | Wholesale & retail | 1991 |
| Koivu Medical Oy | Health & social care | 2010 |
| Koivulan Väri Oy | Manufacturing | 2017 |
| Koivulaukka Oy | Professional & scientific | 2010 |
| Koivunen Security Consulting Oy | Information & communication | 2022 |
| Kojo Jalonen Oy | Arts & recreation | 2012 |
| Kokit Keittiöt Oy | Real estate | 2025 |
| Kokki ja vaimo Oy | Hospitality | 2018 |
| Kokomestari Oy Turku | Construction | 1991 |
| Kokonaisapu Oy | Real estate | 1998 |
| Kokoo oy | Wholesale & retail | 2014 |
| Kolarikorjaamo Hellman Oy | Other services | 2021 |
| Kole Holding Oy | Financial services | 2025 |
| Kolet Oy | Real estate | 2019 |
| Kollabi Oy | Professional & scientific | 2026 |
| Kolmas Kartano Oy | Wholesale & retail | 1991 |
| Kolmio Putki Oy | Construction | 2007 |
| Kolors By Mikko Oy | Other services | 2019 |
| Komate Oy | Professional & scientific | 2013 |
| Kombinova Oy | Wholesale & retail | 1990 |
| Komero Games Oy | Information & communication | 2024 |
| Komero Oy | Hospitality | 1989 |
| Komia Control Oy | Administrative & support | 2023 |
| Kommandiittiyhtiö Kotiruokapalvelu Hemmat Kommanditbolag | Hospitality | 2005 |
| Kommunikaatiokeskus Telmii Oy | Health & social care | 2010 |
| Kompare Finance Oy | Financial services | 2023 |
| Komsat Oy | Construction | 2009 |
| Konde Company OY | Health & social care | 2023 |
| Kone Lahdenmaa Oy | Wholesale & retail | 2020 |
| Kone-Kunttila Oy | Manufacturing | 1999 |
| Kone-Tuomen Kiinteistöt Oy | Real estate | 1989 |
| Kone-Tuomi Oy | Manufacturing | 1982 |
| KoneVeljet Oy | Wholesale & retail | 2020 |
| Konehansa Oy | Construction | 2013 |
| Koneheinä Ky | Construction | 2002 |
| Koneistamo R. Poskiparta Oy | Manufacturing | 1995 |
| Konekylä Oy | Wholesale & retail | 2024 |
| Koneliike AJB Oy | Wholesale & retail | 1987 |
| Konepaja Heikka avoin yhtiö | Manufacturing | 1974 |
| Konepaja P. Uusitalo Oy | Manufacturing | 1995 |
| Konepalvelu Gunn Oy | Construction | 2024 |
| Konepalvelu Osa Oy | Manufacturing | 2007 |
| Konetoimi Oy Turku | Wholesale & retail | 2023 |
| Konetoimi Oy Veikko Sihvo | Real estate | 1982 |
| Koneurakointi Reunanen Oy | Construction | 2026 |
| Koneurakointi Tuuli Oy | Construction | 2019 |
| Konri Oy | Real estate | 2006 |
| Konsekon Ky | Professional & scientific | 1991 |
| Konstruction Oy | Construction | 2022 |
| Konsultointi Lahtiluoma Oy | Professional & scientific | 2024 |
| Konsultointi Tapani Kulmala Oy | Professional & scientific | 2016 |
| Konsultointi Vistaco Oy | Professional & scientific | 1994 |
| Konsultointi- ja Kodinkohennus Rusanen Oy | Professional & scientific | 2015 |
| Konsulttikiinteistöt Oy | Real estate | 2019 |
| Konsulttikollegat Oy | Professional & scientific | 1974 |
| Konsulttiverkosto Black & White Oy | Professional & scientific | 2021 |
| Konttinen-Kultavirta Oy | Wholesale & retail | 1975 |
| Konza Oy | Information & communication | 2021 |
| Koocee Oy | Financial services | 2010 |
| Koodiketo Oy | Information & communication | 2015 |
| Koodineuvos Oy | Information & communication | 2022 |