| Järvi-Suomen Voitelutukku Oy | Wholesale & retail | 2023 |
| Jåuni Oy | Professional & scientific | 2014 |
| K & P Kuljetus Oy | Professional & scientific | 2013 |
| K & T. Sandberg Oy | Wholesale & retail | 2019 |
| K Kiema Oy | Financial services | 2025 |
| K&M Siivous Oy | Administrative & support | 2025 |
| K&S perhepizza Oy | Hospitality | 2023 |
| K2 Invest Oy | Real estate | 2008 |
| K22 Finance Oy | Financial services | 2010 |
| KAKO Oy | Real estate | 2022 |
| KAN-Invest Oy | Financial services | 2019 |
| KD-Teknik Oy | Professional & scientific | 1992 |
| KH Autopalvelu Oy | Other services | 2010 |
| KJData Avoin yhtiö | Information & communication | 2008 |
| KK Kodin Keittiöpiste Oy | Wholesale & retail | 2004 |
| Kk-Kuva OY | Professional & scientific | 1987 |
| KLAH Oy | Health & social care | 2022 |
| Klurex -Tec OY | Information & communication | 2021 |
| KM Apunasi Oy | Construction | 2023 |
| KM Nordic Oy | Other services | 2019 |
| KM-Yhtymä Oy | Manufacturing | 1920 |
| KME Oy | Agriculture & fishing | 2007 |
| KOY Joensuun Ukkolantie 4 | Real estate | 2025 |
| KOy Lekatie 4b | Real estate | 2015 |
| KOy Rahkeentie 4 | Real estate | 2025 |
| KR-Konsultit Oy | Real estate | 1996 |
| KRJ Konsultointi Oy | Professional & scientific | 2021 |
| KSK Rakennus oy | Construction | 2023 |
| KSV-tuotanto Oy | Wholesale & retail | 2013 |
| KT Counter Oy | Professional & scientific | 2017 |
| Kuulas Unit Osk | Professional & scientific | 2021 |
| Kaakkuriranta Oy | Real estate | 1993 |
| Kaakkurivaara Oy | Real estate | 1993 |
| Kaari Pub Oy | Hospitality | 2009 |
| Kahvila Kissaten Avoin yhtiö | Hospitality | 2016 |
| Kahvila-Ravintola Ekin Pub Ky | Hospitality | 1987 |
| Kahvila-Ravintola Kesti-Kulma Ky | Hospitality | 1987 |
| Kahvionni Ky | Hospitality | 2015 |
| Kainoma Oy | Professional & scientific | 2021 |
| Kainulaisen Hautauspalvelu Oy | Other services | 2016 |
| Kaisa Huhta Consulting Oy | Professional & scientific | 2025 |
| Kaita Company Oy | Professional & scientific | 2021 |
| Kaivuliike 122393 Ky | | 1972 |
| Kaivupalvelu Karhapää Oy | Construction | 1990 |
| Kajana Kodit Oy | Wholesale & retail | 2010 |
| Kajoa Company Oy | Construction | 2025 |
| Kakkonen-Yhtiöt Oy | Administrative & support | 1989 |
| Kakkosen Ikkunat Oy | Construction | 2023 |
| Kalakeisari Oy | Agriculture & fishing | 2024 |
| Kalevi Heikkinen Holding Oy | Financial services | 2020 |
| Kalustepitko Oy | Wholesale & retail | 2022 |
| Kammarin sekatavara Oy | Wholesale & retail | 2015 |
| Kantoapu Joensuu Oy | Transport & logistics | 2018 |
| Kanve Oy | Other services | 2014 |
| Kaplan Capital Oy | Professional & scientific | 2021 |
| Kapu Kiinteistöt Oy | Financial services | 1993 |
| Karelcom Oy | Real estate | 1981 |
| Karelia Agro Oy | Wholesale & retail | 2021 |
| Karelia Ammattikorkeakoulu Oy | Education | 2012 |
| Karelia Apartments Oy | Hospitality | 2017 |
| Karelia Cottages Oy | Administrative & support | 2009 |
| Karelia Embedded Oy | Information & communication | 2026 |
| Karelia Invest Oy | Real estate | 2020 |
| Karelia Kiinteistönvälitys Oy | Real estate | 2025 |
| Karelia Metwo Oy | Administrative & support | 1993 |
| Karelia Mix Oy | Wholesale & retail | 1993 |
| Karelia Rent Oy | Administrative & support | 2024 |
| Karelia Truck Service Oy | Other services | 2023 |
| Karelia Wave Oy | Wholesale & retail | 1997 |
| Karelia underground services oy | Mining & quarrying | 2025 |
| Karelia-Agora Oy | Education | 2014 |
| Karelian Adventures Oy | Administrative & support | 2003 |
| Karelian Capital Investment Oy | Financial services | 2026 |
| Karelian Kiinteistökehitys Oy | Real estate | 2004 |
| Karelian Kiinteistötili Oy | Real estate | 2012 |
| Karelian Paju Oy | Manufacturing | 2022 |
| Karelian Sähkö Oy | Construction | 2005 |
| Karelian Talotekniikka OY | Construction | 2015 |
| Karelian Tilintarkastajat Oy | Professional & scientific | 2025 |
| Karelics Oy | Information & communication | 2019 |
| Karelwood Oy | Agriculture & fishing | 2010 |
| Karha Oy | Financial services | 2018 |
| Karhunmäen Puutarha Oy | Agriculture & fishing | 2021 |
| Karhype oy | Construction | 2025 |
| Kari Väistö Oy | Financial services | 1986 |
| Karikola Oy | Arts & recreation | 2023 |
| Karin Auto Ky | Wholesale & retail | 2010 |
| Karjalan Datahuolto Oy | Other services | 1995 |
| Karjalan Ekokatot Oy | Construction | 2022 |
| Karjalan Energiaporaus Oy | Construction | 2022 |
| Karjalan Erämatkat Oy | Administrative & support | 1995 |
| Karjalan Kaihdin Oy | Wholesale & retail | 1999 |
| Karjalan Kiinteistökehitys Oy | Real estate | 2012 |
| Karjalan Kone-Hydro Oy | Wholesale & retail | 1985 |
| Karjalan Kuljetuspalvelu Ky | Transport & logistics | 1979 |
| Karjalan Kumbuzil Oy | Manufacturing | 2021 |
| Karjalan Laatulattia Oy | Construction | 2018 |
| Karjalan MediaCenter Oy | Administrative & support | 2012 |
| Karjalan Mestarit Oy | Construction | 2011 |
| Karjalan Metsätilat Oy | Real estate | 2004 |