| Huviharju oy | Other services | 2017 |
| Hyvinvointikeskus FlowFit Oy | Arts & recreation | 2017 |
| Hyvinvointipalvelu Steppi Oy | Health & social care | 2013 |
| Indigo Management Oy | Arts & recreation | 2023 |
| Infraho Oy | Construction | 2025 |
| Ipin Maatalouspalvelu Oy | Administrative & support | 2023 |
| J. Tölli Oy | Construction | 2011 |
| J.Rajaniemi Oy | Agriculture & fishing | 2023 |
| Janko OY | Manufacturing | 2016 |
| JE Team Oy | Transport & logistics | 2008 |
| JE Vähäsöyrinki Oy | Transport & logistics | 2007 |
| JHT Logistics Oy | Transport & logistics | 2023 |
| JJT Group Oy | Administrative & support | 2022 |
| JKN Service Oy | Other services | 2020 |
| JKR-Motors Oy | Wholesale & retail | 2019 |
| JM Machine Oy | Manufacturing | 2017 |
| JM Tekniikka Finland Oy | Manufacturing | 2019 |
| JMS SIM Oy | Arts & recreation | 2026 |
| JMservitek OY | Manufacturing | 2025 |
| JP Höylä OY | Construction | 2023 |
| JP Paino & Palvelu Ky | Professional & scientific | 1996 |
| JSP INFRA avoin yhtiö | Construction | 2019 |
| Janfix oy | Construction | 2022 |
| Jarsatech oy | Mining & quarrying | 2022 |
| Jiiri-Ikkunat Oy | Construction | 1995 |
| Jivaco Oy | Construction | 2002 |
| Joki Kuokka Oy | Agriculture & fishing | 2025 |
| Joki-Pohjanmaan Osuuspankki | Financial services | 1915 |
| Jokiedu Oy | Education | 2015 |
| Jokihovi Oy | Real estate | 2019 |
| Jokihovin kahvila Oy | Hospitality | 2026 |
| Jokilaaksojen Ravinnekierto Oy | Manufacturing | 2025 |
| Jopel Oy | Construction | 2025 |
| Jopepo Oy | Manufacturing | 2022 |
| Jouni Korkiakoski Oy | Transport & logistics | 1991 |
| JuPek Oy | Agriculture & fishing | 2024 |
| Juho Järvelä Oy | Agriculture & fishing | 2022 |
| Juperi Oy | Construction | 2019 |
| Jusila Oy | Manufacturing | 2019 |
| Jussi Palola Oy | Agriculture & fishing | 2025 |
| Juuriverso Oy | Education | 1999 |
| Järvi & Selkäinaho oy | Administrative & support | 2023 |
| K&K Vesi ja kiinteistötekniikka Oy | Water & waste | 2022 |
| K&P Konepalvelu Oy | Transport & logistics | 2021 |
| KK-Machine Oy | Wholesale & retail | 2015 |
| KSBR Rent Oy | Administrative & support | 1980 |
| KUJUMA Oy | Agriculture & fishing | 2023 |
| Kaarlelan Murske Oy | Mining & quarrying | 1986 |
| Kahvila Myllypub Oy | Hospitality | 1993 |
| Kaisa Liinamaa Oy | Professional & scientific | 2004 |
| Kaisa Pihlajaniemi Oy | Education | 2025 |
| Kaivopuiston Bexat Oy | Wholesale & retail | 2016 |
| Kalajokilaakson Hopeagolf Oy | Arts & recreation | 1997 |
| Kalajokilaakson Varmakoti Ky | Wholesale & retail | 2007 |
| Kallion Tila Oy | Agriculture & fishing | 2009 |
| Kari Saukko Oy | Financial services | 2024 |
| Karjasi Oy | Administrative & support | 2026 |
| Karppinen Invest Oy | Financial services | 2025 |
| Karvos Oy | Real estate | 2025 |
| Kauneushuone Dávenna Oy | Other services | 2017 |
| Kehityspiste Oy | Professional & scientific | 2007 |
| Kellosepänliike R. Sammallahti Kommandiittiyhtiö | Wholesale & retail | 1951 |
| Keskimehtä Oy | Real estate | 2004 |
| Kiekon Konepalvelu Oy | Agriculture & fishing | 2026 |
| Kiinteistö Oy Kesti | Real estate | 1976 |
| Kiinteistö Oy Lisävilja | Real estate | 1980 |
| Kiinteistö Oy Nivalan Forum | Real estate | 1989 |
| Kiinteistö Oy Nivalan Kauppa-asema | Real estate | 2005 |
| Kiinteistö Oy Nivalan Ostokeskus | Real estate | 1965 |
| Kiinteistö Oy Nivalan Vuokrakodit | Real estate | 1989 |
| Kiinteistö Oy Reilari | Real estate | 1991 |
| Kiinteistö Tölli Oy | Real estate | 2025 |
| Kiinteistöyhtiö Korkiakoski Ky | Real estate | 2020 |
| Kirjapaino Kuki Ky | Information & communication | 1999 |
| Klabite Oy | Health & social care | 2020 |
| Knuutin Tila Oy | Agriculture & fishing | 2019 |
| Koiviston Tila Oy | Agriculture & fishing | 2014 |
| Kone Lepistö Oy | Mining & quarrying | 2004 |
| Kone Ollikainen Oy | Construction | 2012 |
| KoneTeam Ahlholm Oy | Agriculture & fishing | 2026 |
| Konehuolto Juha Korri Oy | Other services | 2017 |
| Konehuolto Paavo Liinamaa Oy | Manufacturing | 2000 |
| Koneliike Leo Myllylä Ky | Real estate | 1963 |
| Konepalvelu Veljekset Kaarlela Oy | Construction | 2006 |
| Konesa Oy | Wholesale & retail | 2015 |
| Konetyö A.Kangas Ky | Agriculture & fishing | 2013 |
| Konetyö Haiju avoin yhtiö | Construction | 2012 |
| Koneurakointi H&J Vainio Oy | Agriculture & fishing | 2013 |
| Koneurakointi Hautamäki Oy | Administrative & support | 2014 |
| Koneurakointi Karvola Oy | Agriculture & fishing | 2011 |
| Koneurakointi M. Sikala Oy | Agriculture & fishing | 2024 |
| Koneurakoitsijat Kangas Oy | Agriculture & fishing | 1981 |
| Koodikon Oy | Information & communication | 2018 |
| Kopola Invest Oy | Financial services | 2011 |
| Korkiakosken Auto Ky | Wholesale & retail | 1981 |
| Korpifiber Oy | Construction | 2019 |
| Korpihalli Oy | Real estate | 2024 |
| Korpimachine Oy | Construction | 2020 |
| Korrin Tila Oy | Agriculture & fishing | 2013 |
| Kosken Hirsirakennus Oy | Agriculture & fishing | 2015 |