| Kujala Productions Finland Oy | Professional & scientific | 2019 |
| Kukkagalleria Oy | Wholesale & retail | 2018 |
| Kukkaviljelmät Ristolainen Oy | Agriculture & fishing | 2000 |
| Kulerak Oy | Construction | 2020 |
| Kuljetus Hapulahti Oy | Transport & logistics | 2001 |
| Kuljetus Kari Kuutti Oy | Transport & logistics | 1997 |
| Kuljetus T. Viren Oy | Transport & logistics | 2006 |
| Kuljetus Uimonen Oy | Transport & logistics | 2000 |
| Kuljetus V Tiihonen oy | Transport & logistics | 2020 |
| Kuljetus V. Hölttä Oy | Transport & logistics | 1989 |
| Kuljetusliike Harri Vepsä, Kommandiittiyhtiö | Transport & logistics | 1983 |
| Kuljetusliike Veijo Lahti Oy | Transport & logistics | 1984 |
| Kuljetuspalvelu M. Jokinen Oy | Professional & scientific | 1994 |
| Kuljetuspalvelu Uusitalo Ky | Transport & logistics | 1989 |
| Kulkukauppias Puhakka Ky | Professional & scientific | 2010 |
| Kulkuri & Kiulu Oy | Hospitality | 2026 |
| Kultakausi Hoito Avoin yhtiö | Health & social care | 2019 |
| Kultasepänliike Holmroos & Kni | Wholesale & retail | 1985 |
| Kumera Drives Oy | Manufacturing | 1999 |
| Kumera Oy | Professional & scientific | 1999 |
| Kunkkukiinteistöt Suomi Oy | Real estate | 2019 |
| Kuntokeskus Riihimäki Oy | Arts & recreation | 2018 |
| Kuolion rakennuspalvelu Ky | Construction | 2011 |
| Kurottajapalvelu Eero Koppinen Oy | Construction | 2007 |
| KuvaaJanne Ky | Professional & scientific | 2007 |
| Kuvamestarit Oy | Professional & scientific | 2001 |
| Kyjo Oy | Arts & recreation | 2009 |
| L.Blom Oy | Wholesale & retail | 2021 |
| LA-Laboratories Ltd Oy | Manufacturing | 1996 |
| LES Co Oy | Administrative & support | 2026 |
| LT Urakointi Oy | Construction | 2021 |
| LTEH Holdings Oy | Professional & scientific | 2019 |
| Lujacom OY | Construction | 2016 |
| LVI-Eristys Puhakainen Oy | Construction | 1996 |
| LVI-Ivetek Oy | Construction | 2009 |
| Lvi-Kiva OY | Construction | 2015 |
| LVI-asennus S. Elomaa Ky | Construction | 1986 |
| LVI-asennus Ässät Oy | Construction | 2002 |
| LaRue Oy | Wholesale & retail | 1998 |
| Laaki Industries Oy | Financial services | 2017 |
| Laattatyö Kanervo Oy | Construction | 2020 |
| Lahjan Kammari Oy | Wholesale & retail | 2025 |
| Laitehuolto ja asennus Stenroos Ky | Manufacturing | 2001 |
| Laitila Tooling Oy | Manufacturing | 2021 |
| Lakiasiaintoimisto Harri Hellsten Oy | Professional & scientific | 2019 |
| Lakiasiaintoimisto M. Arola Oy | Professional & scientific | 2007 |
| Lambdapusher Oy | Information & communication | 2022 |
| Lamifer Oy | Wholesale & retail | 1999 |
| Lantmännen Maatalouskauppa Oy | Wholesale & retail | 2016 |
| Larqa Oy | Professional & scientific | 2025 |
| Laser Center Finland Oy | Manufacturing | 2006 |
| Lasiliiri Oy | Manufacturing | 1966 |
| Lasitehtaan Liiketalo Oy | Real estate | 1963 |
| Lasten Pukutalo Satu Prinkkilä Oy | Wholesale & retail | 1970 |
| Latocaster Oy | Arts & recreation | 2021 |
| Launossähkö Oy | Construction | 1988 |
| Laurinharju Ky | Professional & scientific | 1999 |
| Lavasteverstas Graniitti Oy | Arts & recreation | 2019 |
| Lean Reach Oy | Professional & scientific | 2019 |
| Legion Oy | Arts & recreation | 2016 |
| Lehtolantien Pysäköinti Oy | Real estate | 2017 |
| Leipomo Juuri Oy | Manufacturing | 2018 |
| Leipomo Kaneli Ky | Hospitality | 1983 |
| Lempea Edge Oy | Information & communication | 2019 |
| Lempivaara Oy | Hospitality | 2015 |
| Leppäniemen Kauppahuone Oy | Professional & scientific | 2011 |
| Lepän parketti Oy | Construction | 2014 |
| Leverty Oy | Professional & scientific | 2024 |
| Libitina Oy | Other services | 2021 |
| Liikuntakeskus Titan24 Oy | Arts & recreation | 2022 |
| Lippuagentti Oy | Administrative & support | 1998 |
| Liski Group Oy | Professional & scientific | 2014 |
| Lisäpalvelu Kanta-Häme Oy | Administrative & support | 2009 |
| Little Maya Oy | Manufacturing | 2019 |
| Living Leather Oy | Real estate | 2022 |
| Lobhius Oy | Financial services | 1992 |
| LocoFit Oy | Arts & recreation | 1998 |
| LogOn Finland Oy | Professional & scientific | 2021 |
| Logisteam Oy | Professional & scientific | 2004 |
| Logistone Oy | Information & communication | 2013 |
| Lohisaari Oy | Professional & scientific | 2011 |
| LongDog Oy | Wholesale & retail | 2026 |
| Lopen Kirjapaino Ky | Manufacturing | 1987 |
| Lopen Liikennekoulu Oy | Education | 2008 |
| Lopen Maa ja Vesirakenne Oy | Construction | 2000 |
| Lopen Studiokuva Oy | Wholesale & retail | 2001 |
| Louhi Propulsion Oy | Manufacturing | 2026 |
| Louhintavaruste Matti Aalto Ky | | 1980 |
| Lovan Oy | Hospitality | 2025 |
| Lucky Day Events Oy | Other services | 2023 |
| Lumelia Oy | Health & social care | 2025 |
| Lumra Oy | Manufacturing | 2026 |
| Luonto-Osuuskunta Willimieli | Administrative & support | 2015 |
| Luontokunta osk | Administrative & support | 2021 |
| Luoteen Katto&Perusta Oy | Administrative & support | 2005 |
| LuovaQ Oy | Professional & scientific | 2025 |
| Luukkainen Yhtiöt Oy | Administrative & support | 1994 |
| Lämpötaituri Oy | Construction | 2024 |
| Länsäri Oy | Administrative & support | 1990 |
| M & R Dance Academy Oy | Arts & recreation | 1996 |