| J & A Mäkelä Oy | Wholesale & retail | 1994 |
| J&A-tilat Oy | Real estate | 2025 |
| J-Block Oy | Real estate | 2024 |
| J-P Markkinointi Oy | Arts & recreation | 2015 |
| J. Elg Oy | Manufacturing | 2005 |
| J. Kortelainen Oy | Construction | 1998 |
| J.Korkeakangas Oy | Arts & recreation | 2019 |
| JA Sähkö Oy | Construction | 2017 |
| JAH Partnerit Oy | Financial services | 2014 |
| JH Innovations Oy | Manufacturing | 2016 |
| JK EcoElementti Oy | Manufacturing | 2025 |
| JM Control Oy | Professional & scientific | 2013 |
| JMP Group Oy | Administrative & support | 2021 |
| JOAB Finland Oy | Manufacturing | 2018 |
| JR-Hake ja Kuljetus Oy | Agriculture & fishing | 2010 |
| Jaakko Saartoala Invest Oy | Construction | 2012 |
| Jalve Rakennuspalvelut Oy | Administrative & support | 2020 |
| JanLa Oy | Manufacturing | 2004 |
| Jiisvee Oy | Wholesale & retail | 2013 |
| Joutomieslupi Oy | Real estate | 1992 |
| Jovans Oy | Wholesale & retail | 2023 |
| Jukanlan Dataranch Oy | Agriculture & fishing | 1982 |
| Jukolan Puu Oy | Professional & scientific | 1994 |
| Jundoor Oy | Transport & logistics | 1993 |
| Juonek Oy | Transport & logistics | 2022 |
| Jupi Holdings Oy | Financial services | 2025 |
| Jusako Oy | Construction | 2020 |
| Juvex Oy | Information & communication | 2017 |
| Jyshalli Oy | Real estate | 2025 |
| Jänkäjoonas Oy | Construction | 2026 |
| Järvien Oy | Other services | 2021 |
| K & N Uhlbäck Ky | Transport & logistics | 2011 |
| K&N Viimistely oy | Construction | 2022 |
| K&R Finland Construction Oy | Professional & scientific | 2019 |
| KAJOSA-Rakennus oy | Construction | 2025 |
| KB Components Finland Oy | Manufacturing | 2024 |
| Kirpel OY | Education | 2016 |
| KJ-Laaksonen Oy | Health & social care | 1998 |
| KJP-Invest Oy | Financial services | 1992 |
| KL-Palvelut Oy | Administrative & support | 2020 |
| KP Tili ja Konsultointi KY | Professional & scientific | 2007 |
| KTV Group Oy | Wholesale & retail | 2026 |
| Kaido Trans Oy | Transport & logistics | 2017 |
| Kaihonkukka ja hautauspalvelut Oy | Wholesale & retail | 2026 |
| Kaivu Seiteri Oy | Construction | 1988 |
| Kalev Yhtiöt Oy | Construction | 2008 |
| Kalevi Österberg Ky | Wholesale & retail | 1983 |
| KarhuHalli Oy | Real estate | 2000 |
| Karhun Palvelus Oy | Construction | 2004 |
| Karhunkorven Auto Oy | Wholesale & retail | 2023 |
| Kari Ring Oy | Transport & logistics | 2002 |
| Kari Uosukainen Oy | Construction | 2022 |
| Karppalan Kauppayhtiö Lietolahti ja Kni | Wholesale & retail | 1966 |
| Karppiset & co Oy | Real estate | 2018 |
| Kartanon Leipä Oy Inkiläinen | Manufacturing | 1975 |
| Kartini Oy | Professional & scientific | 2020 |
| Kasvutec Oy | Professional & scientific | 2020 |
| Kataja Event Oy | Administrative & support | 2000 |
| Kattokeskus Uusimaa Oy | Construction | 2019 |
| Katu-Karhu Oy | Construction | 1996 |
| Kauppahuone Hakkala Oy | Wholesale & retail | 2013 |
| Kauppi Company Oy | Information & communication | 2023 |
| Kavenza Oy | Wholesale & retail | 2023 |
| Kerasil Oy | Wholesale & retail | 2007 |
| Keski-Uudenmaan Työterveys Oy | Health & social care | 2017 |
| Kestävä Suunta Oy | Wholesale & retail | 2022 |
| Kh Forest Oy | Agriculture & fishing | 2018 |
| Kiesel Finland Oy | Wholesale & retail | 2001 |
| Kiinteistö Oy Ilvesvuorenkatu 11 | Real estate | 2010 |
| Kiinteistö Oy Impivaara | Real estate | 1961 |
| Kiinteistö Oy Kauppahuitti | Real estate | 1984 |
| Kiinteistö Oy Kuusimäentie 13 | Real estate | 2001 |
| Kiinteistö Oy Kuusimäentie 17 | Real estate | 2015 |
| Kiinteistö Oy Levin Länsirinne | Real estate | 2006 |
| Kiinteistö Oy Mara | Real estate | 1988 |
| Kiinteistö Oy Nurmijärven Ahmatie 4 | Real estate | 1988 |
| Kiinteistö Oy Nurmijärven Ilveskaari 25 | Real estate | 2018 |
| Kiinteistö Oy Nurmijärven Ilveskuja 5 | Real estate | 2008 |
| Kiinteistö Oy Nurmijärven Otsotie | Real estate | 1990 |
| Kiinteistö Oy Otsotie 2 | Real estate | 1988 |
| Kiinteistö Oy Pijo | Real estate | 1988 |
| Kiinteistö Oy Pratikankuja 13 | Real estate | 1986 |
| Kiinteistö Oy Raalantie | Real estate | 1985 |
| Kiinteistö Oy Savimes | Real estate | 1982 |
| Kiinteistö Oy Toijalan Asema | Real estate | 2025 |
| Kiinteistö- ja SijoitusHovi Oy | Real estate | 1977 |
| Kiinteistöhuolto Rahkola Oy | Real estate | 2024 |
| Kiinteistönhoito Pentti Lakaniemi Oy | Administrative & support | 1989 |
| Kiinteistöpalvelu Heila Oy | Administrative & support | 1990 |
| Kiinteistöportaali Oy | Real estate | 1988 |
| Kiitis Oy | Wholesale & retail | 2026 |
| Kiitologi Oy | Transport & logistics | 2007 |
| Kimet Oy | Wholesale & retail | 2023 |
| Kimmon kattomaalaus ja -huolto Oy | Construction | 2011 |
| Kingi Oy | Manufacturing | 2002 |
| Kino Juha Oy | Arts & recreation | 2021 |
| Kirbeto Oy | Manufacturing | 2025 |
| Kirjanpito & Laskenta Tuula Jansson Ky | Professional & scientific | 1995 |
| Kirjanpitolaskenta TJ Oy | Education | 1998 |
| Kirjava Puoti Oy | Wholesale & retail | 2014 |