| Kotona Asuen Palvelut Oy | Health & social care | 2015 |
| Kotosan Oy | Construction | 2021 |
| Kotova Oy | Administrative & support | 2018 |
| Kotro Consulting Oy | Financial services | 2025 |
| Kotva Games Oy | Information & communication | 2015 |
| Kouda Oy | Information & communication | 2025 |
| Kouhi Invest Oy | Professional & scientific | 1993 |
| Koukkusormi Oy | Professional & scientific | 2014 |
| Koukus Oy | Information & communication | 2023 |
| Koukut Kiinni Oy | Information & communication | 2021 |
| Koulumatkailutoimisto Oy | Administrative & support | 1939 |
| Koulun hyvinvointipalvelut WELP Oy | Information & communication | 2018 |
| Koulutettujen akupunktiohoitajien osuuskunta | Health & social care | 2017 |
| Koulutus Klaavu Oy | Education | 2025 |
| Koulutus ja Konsultointi Kokojuha Oy | Professional & scientific | 2025 |
| Koulutus ja työnohjaus Talvio Oy | Education | 2009 |
| Koulutusakatemia Helsinki Oy | Administrative & support | 2016 |
| Koulutuskeskus O.I.F Oy | Health & social care | 2016 |
| Koulutuskeskus Taito Oy | Education | 2018 |
| Koulutuskeskus Unika Hairstyle Oy | Other services | 2009 |
| Koulutuskollektiivi Oy | Professional & scientific | 2023 |
| Koulutuskonsultointi Maiccon - M Mustajoki Ky | Education | 1992 |
| Koulutuskonttori Oy | Education | 2021 |
| Koulutuspalvelu Didactica Oy | Financial services | 1989 |
| Kouran palvelut Oy | Administrative & support | 2022 |
| Kouruapu Oy | Administrative & support | 2025 |
| Kourukoski Oy | Hospitality | 2021 |
| Kouta Media Oy | Professional & scientific | 2022 |
| Kouta Productions Oy | Information & communication | 2017 |
| Koutsi - Coach Oy | Education | 2015 |
| Koutsit Group Oy | Education | 2017 |
| Koutsiteam Oy | Professional & scientific | 2026 |
| Kouva Group Oy | Construction | 2025 |
| Kouva Levi Oy | Construction | 2025 |
| Kouvola Ace Systems Oy | Professional & scientific | 1995 |
| Kouvola East Oy | Hospitality | 2022 |
| Kouvolan Soitinkauppa Ky | Wholesale & retail | 1955 |
| Kouzmina Linguistics Oy | Education | 2014 |
| Kova Housing Oy | Real estate | 2024 |
| Kova Koodi Holding Oy | Professional & scientific | 2023 |
| Kova Labs Oy | Manufacturing | 2025 |
| Kovakulma Oy | Construction | 2023 |
| Kovalent Capital Oy | Financial services | 2017 |
| Kovaluku Oy | Professional & scientific | 2023 |
| Kovamet Oy | Real estate | 2013 |
| Kovanen Capital Oy | Financial services | 2010 |
| Kovanen Invest Oy | Financial services | 2010 |
| Kovanen Yhtiöt Oy | Transport & logistics | 2017 |
| Kovapesu Oy | Administrative & support | 2026 |
| Kovatek Oy | Construction | 2022 |
| Kovenet-TrustSyneReF Oy | Professional & scientific | 2014 |
| Kovertti Oy | Professional & scientific | 1989 |
| Kovest Oy | Financial services | 1986 |
| Kovil Oy | Manufacturing | 1992 |
| Koville Holding Oy | Professional & scientific | 2025 |
| Kovite Oy | Administrative & support | 2011 |
| Kowi & Kowi Oy | Hospitality | 2005 |
| Koy Espoon Ullanmäentie 13 | Real estate | 2021 |
| Koy Espoon Ylismäentie 12 Pysäköinti | Real estate | 2016 |
| Koy Finnoon Kuunari | Real estate | 2021 |
| Koy Graniittikodit | Real estate | 2018 |
| Koy Helsingin Laivalahdenkatu 6d | Real estate | 2023 |
| Koy Helsingin Pihlajistontie 1 | Real estate | 2014 |
| Koy Joensuun Voimatie 16 | Real estate | 2024 |
| Koy Järvenpään Pajalantie 23 G | Real estate | 2025 |
| Koy Kuopion Leväsentie 2b | Real estate | 2024 |
| Koy Kuopion Leväsentie 33 | Real estate | 2024 |
| Koy Lahden Ajokatu 261 | Real estate | 2024 |
| Koy Myyrinhalmeen tontti 1 | Real estate | 2022 |
| Koy Myyrinhalmeen tontti 13 | Real estate | 2022 |
| Koy Naakan Nokka | Real estate | 2018 |
| Koy Santalahden Pintari | Real estate | 2015 |
| Koy TESC Hotel Tampere | Real estate | 2026 |
| Koy Tampereen Hatanpään Valtatie 42 | Real estate | 2024 |
| Koy Tampereen Puistokuja 32 | Real estate | 2024 |
| Koy Turun Pääskyvuorenlaakso D | Real estate | 2018 |
| Koy Veikkolan Teollisuustie 8 | Real estate | 1999 |
| Koy Villa Bläk | Real estate | 2012 |
| Koza Oy | Information & communication | 2025 |
| Kozalak Oy | Wholesale & retail | 2019 |
| Kozeen Shiwan Oy | Hospitality | 2021 |
| Kp Media Oy | Professional & scientific | 2023 |
| Kraateri Oy | Information & communication | 2001 |
| Krafted Motors Finland Oy | Wholesale & retail | 2026 |
| Krafth Ab | Financial services | 2019 |
| Kraftvaerk Finland Oy | Information & communication | 2015 |
| Kraftverk Helsinki Oy | Education | 2008 |
| Kraftvoll Oy | Arts & recreation | 2007 |
| Krakle Oy | Manufacturing | 1990 |
| Kraks Oy | Professional & scientific | 2026 |
| Kralex Oy | Professional & scientific | 2022 |
| Kralle Consulting Oy | Professional & scientific | 2013 |
| Kram INK Oy | Professional & scientific | 2010 |
| Krame Oy | Professional & scientific | 2010 |
| Kramelet Oy | Professional & scientific | 2025 |
| Kramer Electronics Sweden AB Suomen sivuliike | Wholesale & retail | 2012 |
| Krash Oy | Professional & scientific | 2019 |
| Kraskowski Oy | Professional & scientific | 2025 |
| Kratti Holding Oy | Financial services | 2023 |
| Krava Beauty Lab Oy | Other services | 2023 |