| Kuljetus S. Hänninen Ky | Transport & logistics | 1982 |
| Kuljetus Soiniola Oy | Transport & logistics | 1986 |
| Kuljetus T.Sorvali Ky | Transport & logistics | 2005 |
| Kuljetus Tikka Oy | Transport & logistics | 2015 |
| Kuljetus Turku Oy | Transport & logistics | 2012 |
| Kuljetus Ville Kantonen Oy | Transport & logistics | 1996 |
| Kuljetus- ja Kuormausliike Nissinen Oy | Construction | 2021 |
| Kuljetusliike Erkki Mikkola Ky | Transport & logistics | 1994 |
| Kuljetusliike Haugas OY | Transport & logistics | 2016 |
| Kuljetusliike Ilkka Huttunen Oy | Transport & logistics | 2014 |
| Kuljetusliike Ilves & Ilves Oy | Transport & logistics | 1996 |
| Kuljetusliike Kilpi Oy | Transport & logistics | 1987 |
| Kuljetusliike Nikkilä Oy | Transport & logistics | 1997 |
| Kuljetusliike O. Hämäläinen Oy | Transport & logistics | 1981 |
| Kuljetusliike Pöllänen Oy | Transport & logistics | 1967 |
| Kuljetusliike R Tuominen kommandiittiyhtiö | Transport & logistics | 1985 |
| Kuljetusliike Uski Oy | Transport & logistics | 1991 |
| Kulta Wellness Oy | Arts & recreation | 2020 |
| Kulta-Gabriel Ky | Wholesale & retail | 1985 |
| Kultaraati Oy | Financial services | 1989 |
| Kultasumu Oy | Wholesale & retail | 2026 |
| Kulttuuriosuuskunta Avocado | Other services | 1998 |
| Kuntaisännöinti Oy | Real estate | 2020 |
| Kuopion Liikekiinteistöt Oy | Real estate | 2024 |
| Kuormaus ja Kuljetus Toivari Oy | Wholesale & retail | 1989 |
| Kuorttisen Hunaja oy | Agriculture & fishing | 2021 |
| Kuorttisen Sähkö Oy | Construction | 2021 |
| Kupas Oy | Administrative & support | 2021 |
| Kurelco Oy | Construction | 2015 |
| Kurssini Oy | Education | 2021 |
| KutriMix Ky | Wholesale & retail | 2005 |
| Kuuge Oy | Administrative & support | 2022 |
| Kuulo-Tieto Avoinyhtiö Papinniemi & Vesa | Wholesale & retail | 2001 |
| Kuutoskeskus Oy | Real estate | 2004 |
| Kuutoswing Invest Oy | Real estate | 1996 |
| Kuvapaja Oy | Professional & scientific | 1956 |
| Kuvavirta Oy | Professional & scientific | 2025 |
| Ky Pub Leirin Kulma | Hospitality | 2014 |
| Kylmäeristys Koskela Oy | Construction | 1993 |
| Kylmäte Oy | Energy | 2018 |
| Kymecon Oy | Construction | 1996 |
| Kymen Konepalvelu Oy | Transport & logistics | 2010 |
| Kymen Pinnoitus Oy | Construction | 2003 |
| Kymen Siivoustukku ja -konsultointi Oy | Wholesale & retail | 1991 |
| Kymen Sä-Mex Ky | Construction | 1990 |
| Kymen Teollisuusasennus Oy | Manufacturing | 2021 |
| Kymijoen Paratiisi Oy | Real estate | 2006 |
| Kymrak Group Oy | Construction | 2026 |
| Kämpästä kodiksi Oy | Construction | 2023 |
| Käpälämäki Vintage Oy | Wholesale & retail | 2024 |
| Kärkikone Oy | Wholesale & retail | 2023 |
| Käyhty Racing Service Oy | Other services | 2022 |
| L&L Lions Oy | Administrative & support | 2015 |
| LA-Tech Oy | Other services | 2013 |
| LBO Partners Oy | Wholesale & retail | 2026 |
| Lcfa Buffet OY | Hospitality | 2019 |
| LH-Kuljetus Oy | Transport & logistics | 2009 |
| LK Management Oy | Professional & scientific | 2017 |
| LK Ympäristörakenne Oy | Administrative & support | 2010 |
| LL-Tekniikka Oy | Wholesale & retail | 2021 |
| LLA Palvelut Oy | Manufacturing | 2007 |
| LLH-Electric Oy | Manufacturing | 2006 |
| LMK Lappeenranta Oy | Construction | 1986 |
| LMK-Maalausurakointi Oy | Construction | 1993 |
| LMK-Urakointi Oy | Construction | 1996 |
| LMT Consulting Oy | Professional & scientific | 2020 |
| Log-Hog OY | Construction | 2008 |
| Lohikäärme OY | Wholesale & retail | 2008 |
| LP Global Finland Oy | Administrative & support | 2022 |
| LP-Väriyhtymä Oy | Wholesale & retail | 1985 |
| LV-Putkiasia Oy | Construction | 1988 |
| LVI-Toivanen Oy | Construction | 2011 |
| LVI-Työt Pesonen Oy | Construction | 2012 |
| LVI-insinööritoimisto K Kakko Ky | Professional & scientific | 1976 |
| La Bonne Vie Oy | Health & social care | 1994 |
| LaRutiini Oy | Health & social care | 2024 |
| Laatu-Maalaus Muhonen Oy | Construction | 2005 |
| Laatumarkka Ky | Professional & scientific | 1991 |
| Ladontapalvelu Osmo Jurvanen Ky | Manufacturing | 1995 |
| Lahden Bike Marine Oy | Wholesale & retail | 2010 |
| Laineaho Oy | Water & waste | 1994 |
| Laitex Oy | Manufacturing | 1986 |
| Laituri.ai oy | Information & communication | 2026 |
| Lakama Oy | Wholesale & retail | 1990 |
| Lakeland Consulting Oy | Information & communication | 2023 |
| Lakeside e-Bike Oy | Wholesale & retail | 2021 |
| Lakiasiaintoimisto Jukka Väkiparta Oy | Professional & scientific | 1985 |
| Lakiasiaintoimisto Peltonen Juridia Ky | Professional & scientific | 2000 |
| Lakipalvelut Petri Krohns Oy | Professional & scientific | 2024 |
| Lakitoimisto Pekka Havo Ky | Professional & scientific | 1992 |
| Lakumaja Oy | Real estate | 1989 |
| Lamerit Oy | Agriculture & fishing | 1996 |
| LamisNET Palvelut Oy | Information & communication | 2020 |
| LanRak Oy | Construction | 2009 |
| Lappee Design Ky | Manufacturing | 2001 |
| Lappeen Aurinko Oy | Construction | 2019 |
| Lappeen Hammas Ky | Manufacturing | 1981 |
| Lappeen Ikihonka Oy | Real estate | 2009 |
| Lappeen Konepalvelu Oy | Mining & quarrying | 1997 |
| Lappeen Metsäpalvelu Oy | Agriculture & fishing | 2008 |