| Jyvä Innovations Oy | Financial services | 2019 |
| Jära Group Oy | Transport & logistics | 2018 |
| Järvenpään Kirje- & Lomakepaino Oy | Real estate | 1987 |
| Järvenpään Rakennustaito Oy | Construction | 1994 |
| Järvi Kodit Oy | Construction | 2022 |
| K & K Autohuolto Oy | Other services | 2020 |
| K & K Kivinen Oy | Wholesale & retail | 1993 |
| K&K Pro Grupp Oy | Construction | 2025 |
| K-U Kotikiinteistöt Oy | Administrative & support | 2019 |
| K. Himberg Oy | Wholesale & retail | 2011 |
| K.Fux Oy | Construction | 2019 |
| K2K Kosmetologi Tarja Juutistenaho Oy | Other services | 2017 |
| KA Group Oy | Construction | 2022 |
| KA Investment oy | Construction | 2012 |
| KARH Rakennus Oy | Construction | 2021 |
| KEX Invest Oy | Real estate | 2023 |
| KFX Finland Oy | Information & communication | 2007 |
| KG Group Oy | Wholesale & retail | 2026 |
| KH Stores Oy | Wholesale & retail | 2022 |
| KHS- Partner Oy | Administrative & support | 2013 |
| Kimare OY | Construction | 2012 |
| KIPINÄ SPARKS Oy | Education | 2021 |
| KK Ventures Oy | Financial services | 2022 |
| KK-Kolmoset Oy | Wholesale & retail | 1997 |
| KKM Nordic Oy | Professional & scientific | 2023 |
| KL Toimistopalvelut Oy | Professional & scientific | 2012 |
| KLK Palvelut Oy | Other services | 2022 |
| KLL Palvelut Oy | Manufacturing | 2020 |
| Kls-Lvi OY | Construction | 2026 |
| KMR Motors Oy | Other services | 2022 |
| KMV Kotipalvelut Oy | Administrative & support | 2013 |
| KNS Team Oy | Construction | 2019 |
| KO Pakkaus Oy | Manufacturing | 2016 |
| Koko Putki OY | Construction | 2020 |
| KOVA TRAINING Oy | Arts & recreation | 2025 |
| KOVA pmc Oy | Professional & scientific | 2019 |
| KOY Tuusulan Ruutu | Real estate | 2023 |
| KOy Otavaisentie 2 | Real estate | 2022 |
| KPH Purkutyöt Oy | Construction | 2026 |
| KPU-Jakelu Oy | Transport & logistics | 1994 |
| KR-Saneeraus Oy | Construction | 2024 |
| KT Accounting Oy | Professional & scientific | 2024 |
| KT Paloturvapalvelut Oy | Construction | 2017 |
| KTV Terminal Oy | Transport & logistics | 2018 |
| Kuusi Yhtiö OY | Transport & logistics | 2018 |
| KV-Invest Oy | Real estate | 2019 |
| KVG Helsinki Oy | Information & communication | 2019 |
| KW-Liiketoiminta Oy | Wholesale & retail | 2022 |
| KaRu Automaatio Oy | Construction | 2021 |
| Kaakon Botine Oy | Construction | 2020 |
| Kabas Partners Oy | Construction | 2015 |
| Kadep Oy | Wholesale & retail | 2024 |
| Kaiku Räihä Oy | Construction | 1999 |
| Kainulainen & Pasanen Oy | Real estate | 1975 |
| Kaiska Oy | Construction | 1995 |
| Kaislakerttu Invest Oy | Financial services | 2021 |
| Kaiverrus Cavo Oy | Manufacturing | 1991 |
| Kaivutyö J. Knuutila Oy | Construction | 1997 |
| Kaivuu Pakanen Oy | Construction | 2018 |
| Kaivuupalvelu V. Saarijärvi Oy | Construction | 1999 |
| Kajari Palvelut Oy | Transport & logistics | 2007 |
| Kakkutukku Helsinki Oy | Manufacturing | 1989 |
| Kalecom Oy | Information & communication | 2019 |
| Kalen Racing Oy | Wholesale & retail | 1988 |
| Kalliopohjan Lämpö Oy | Energy | 1974 |
| Kalusteasennus Kantoluoto Oy | Construction | 2013 |
| Kalustekompis Oy | Other services | 2025 |
| Kalustepalvelu Mini Oy | Construction | 2026 |
| Kalustetorni Oy | Wholesale & retail | 1993 |
| Kampek Invest Oy | Construction | 2000 |
| Kanda Invest Oy | Financial services | 2004 |
| Kanki Yhtiöt Oy | Administrative & support | 2005 |
| Kapema Consulting Oy | Professional & scientific | 2023 |
| Kapiljo Oy | Financial services | 2023 |
| Karhu Service Oy | Other services | 2025 |
| Kari Haaranen Oy | Construction | 1990 |
| Karimark hankinta ja myynti Oy | Wholesale & retail | 2002 |
| Karinen Oy | Construction | 1997 |
| Karivaljakko Oy | Wholesale & retail | 1997 |
| Karmo Motorsport Oy | Wholesale & retail | 2018 |
| Karprakennus Oy | Construction | 2018 |
| Kartanon Herra OY | Construction | 2025 |
| Kartanon auto Oy | Wholesale & retail | 1998 |
| Kartore Oy | Construction | 2008 |
| Kassu Invest Oy | Financial services | 2025 |
| Kasvila Oy | Hospitality | 2023 |
| Katax Oy | Financial services | 2025 |
| Kateetti Oy | Information & communication | 2010 |
| Kateplan Oy | Construction | 2001 |
| Katila Sijoitus Oy | Professional & scientific | 2018 |
| Kauneushoitola Pauliina Oy | Other services | 2019 |
| Kauriinkierto Oy | Wholesale & retail | 2022 |
| KeKu Company Oy | Real estate | 2020 |
| Keep Fishin Osk | Information & communication | 2017 |
| Kehitysexpertti Oy | Real estate | 2015 |
| KekeWorks Oy | Other services | 2024 |
| Kelatien Konesuojat Oy | Real estate | 1993 |
| Kenoviiva Oy | Information & communication | 1989 |
| Keravan Agentuuri Oy | Wholesale & retail | 2001 |
| Keravan Kirja-Info Oy | Real estate | 1963 |