| Jaatek Oy | Manufacturing | 2021 |
| Jakasavi Oy | Manufacturing | 2021 |
| Jalapa Oy | Hospitality | 2021 |
| Jansuho Oy | Financial services | 1989 |
| Jari Könönen Oy | Administrative & support | 2015 |
| Jasmacin Oy | Construction | 1995 |
| Jebjerat Oy | Real estate | 1993 |
| Jecca Keidas Oy | Manufacturing | 2026 |
| Jecca Kiinteistöt Oy | Real estate | 2026 |
| Jecca Oy | Education | 2023 |
| Jennin Kotiapu Tornio Oy | Other services | 2025 |
| Jenx Oy | Manufacturing | 2018 |
| Jeraworks Oy | Construction | 2024 |
| Jespert Oy | Construction | 2024 |
| Joel Hirsikangas Service Oy | Other services | 2019 |
| Jokamies Oy | Construction | 1990 |
| Jokinen Invest Oy | Real estate | 2017 |
| Jokivarren Korjauspalvelu Oy | Construction | 1999 |
| Jokivarren Leipomo Oy | Manufacturing | 1997 |
| Jokivarren Tekniikka Oy | Construction | 2023 |
| Jokivarren Trans Oy | Transport & logistics | 1996 |
| Jokivarren eräliike Oy | Wholesale & retail | 2015 |
| Jonne Hirsikangas Oy | Other services | 2026 |
| Joona Konttajärvi Oy | Financial services | 2020 |
| Joonas Kuure Oy | Administrative & support | 2025 |
| Jorenta Ky | Administrative & support | 2017 |
| Jorma Savikuja Ky | Transport & logistics | 2015 |
| Jorpau Oy | Hospitality | 2019 |
| Josari Oy | Administrative & support | 2023 |
| Joulupukin Pääkonttori Oy | Professional & scientific | 2012 |
| Jouni Vuokila Oy | Wholesale & retail | 1982 |
| Jp rakentaa oy | Construction | 2023 |
| Juha-Matti Berg Ky | Financial services | 2013 |
| Juho Kujansuu Oy | Transport & logistics | 2017 |
| Jukka Vottonen Oy | Education | 1980 |
| Juntti Yhtymä Oy | Real estate | 2021 |
| Juradin Oy | Information & communication | 1992 |
| Jussilan Liikenne Avoin Yhtiö | Transport & logistics | 2010 |
| Juto Rakennus Oy | Construction | 1994 |
| Jyrimet Oy | Agriculture & fishing | 2008 |
| JÄCY Service Oy | Construction | 2021 |
| K & I Säily Oy | Real estate | 2011 |
| K. Kaihu Oy | Administrative & support | 1983 |
| KALOTTIWORKS avoin yhtiö | Administrative & support | 2003 |
| Kama-Montage OY | Transport & logistics | 2011 |
| Karmet OY | Manufacturing | 2012 |
| KG-GARAGE Oy | Wholesale & retail | 2021 |
| KJ-Isännöinti Oy | Real estate | 2018 |
| KJR hitsaus ja asennus Oy | Manufacturing | 2022 |
| KM-RRR Yhtiöt Oy | Wholesale & retail | 2001 |
| KN Composite Oy | Manufacturing | 1980 |
| KNC Group Oy | Professional & scientific | 2024 |
| Kone- Ja Trukkihuolto Isometsä Ky | Manufacturing | 2006 |
| KOULUTUS JA VIRKISTYS SYDÄMEN NOSTE Ky | Education | 2012 |
| KR Ikkunanpesu avoin yhtiö | Administrative & support | 2025 |
| KSS Invest Oy | Professional & scientific | 2021 |
| KT Pyykönen avoin yhtiö | Wholesale & retail | 2017 |
| Ktk-Tornio OY | Transport & logistics | 1955 |
| Kuljetus Jari Kojola OY | Transport & logistics | 2002 |
| Kuljetusliike Pertti Nättilä OY | Transport & logistics | 2012 |
| Kaakamon Metalli Ky | Construction | 1998 |
| Kaakamon Napakymppi Ky | Hospitality | 2010 |
| Kaakamon Tietoverkko-osuuskunta | Wholesale & retail | 2014 |
| Kaara Rent Oy | Administrative & support | 2025 |
| Kaarakka Palvelut Oy | Construction | 2021 |
| Kaarlela Kiinteistöt Oy | Real estate | 2013 |
| Kaarlo Lassheikki Oy | Mining & quarrying | 1998 |
| Kaarna Invest Oy | Real estate | 2023 |
| Kahvila ja Pitopalvelu Roosamaria Oy | Hospitality | 1996 |
| Kaikenko Oy | Professional & scientific | 2020 |
| Kaivuupalvelu Hirsikangas Oy | Administrative & support | 2021 |
| Kajoar Oy | Real estate | 1997 |
| Kake Container Oy | Administrative & support | 2005 |
| Kalaliike Haavi Ky | Wholesale & retail | 2016 |
| Kalaliike Hast Oy | Wholesale & retail | 1987 |
| Kalles Restaurant Oy | Hospitality | 1996 |
| Kalotti-Sähkö Oy | Construction | 2021 |
| Kalottipalvelu Oy | Transport & logistics | 1989 |
| Kampaamo Silvia Avoin yhtiö | Other services | 2003 |
| Kangasmaailma Oy | Wholesale & retail | 2005 |
| Kangastalo Ky Helena Olsson | Wholesale & retail | 1977 |
| Kantojoen Mäki Oy | Agriculture & fishing | 2023 |
| Kantojärven Metalli Oy | Manufacturing | 2003 |
| Karin Videokeskus Ky | | 1983 |
| Karipekka Equity Oy | Real estate | 2019 |
| Karte Palvelut Oy | Professional & scientific | 2022 |
| Karu Garage Oy | Other services | 2025 |
| Karungin Huoltamo Ky | Wholesale & retail | 2007 |
| Karungin Koneurakointi Oy | Construction | 2010 |
| Karungin Korpikylän Vesiosuuskunta | Water & waste | 2001 |
| Karungin perinnekalastajat osk | Agriculture & fishing | 2008 |
| Kassapojat Ky | Manufacturing | 1981 |
| Kauppahuone Nurkkala Oy | Wholesale & retail | 2006 |
| Kavamet-Konepaja Oy | Manufacturing | 1993 |
| Kavetor Ky | Real estate | 1991 |
| Kelontekemän Matkapirtti Avoin yhtiö | Hospitality | 2000 |
| Kemin Autohuolto Oy | Other services | 1993 |
| Kemin Maalaus ja Tasoite Ky | Construction | 1989 |
| Kemin Siivouspalvelu ARIEL Oy | Administrative & support | 2019 |
| Keminmaan Kuva ja Kamera Ky | | 1983 |