| Lampinen Kiinteistöt Oy | Real estate | 2021 |
| Lampinen Logistics Oy | Transport & logistics | 2013 |
| Lampinen group Oy | Other services | 2019 |
| Lamse Oy | Manufacturing | 2007 |
| Lamte Oy | Construction | 2008 |
| Language Clubhouse Oy | Education | 2019 |
| Lanssi Oy | Professional & scientific | 2005 |
| Lapin Turvasaneeraus Oy | Construction | 1992 |
| Lapland Holiday Resort Oy | Real estate | 2010 |
| Lapuan Kuntokeskus Oy | Arts & recreation | 2002 |
| Larvin Oy | Financial services | 1990 |
| Lastentähdet Oy | Professional & scientific | 2011 |
| Lastu Ohjelmistot Ky | Information & communication | 2005 |
| LatMi Oy | Information & communication | 2022 |
| Laten Kuljetus Ky | Transport & logistics | 2015 |
| Latosaari Company Oy | Real estate | 2024 |
| Latosaari Oy | Construction | 2022 |
| Latte Holding Oy | Financial services | 2017 |
| Latvala Enterprises Oy | Financial services | 2025 |
| Laukkutalo Torikka & Nieminen Oy | Wholesale & retail | 1992 |
| Laura Annala Hair & Beauty Oy | Other services | 2011 |
| Lauran Konepaja Oy | Arts & recreation | 2025 |
| Lauri Viitaniemi Oy | Transport & logistics | 1977 |
| Lautapelikauppa.com Oy | Wholesale & retail | 2022 |
| LePo Isännöinti OY | Real estate | 2018 |
| Leader Design Oy | Professional & scientific | 2025 |
| Lecklé HR Lead Oy | Professional & scientific | 2024 |
| Ledimedia Oy | Professional & scientific | 2012 |
| Lehtimyynti Taira OY | Financial services | 1989 |
| Lehtomäki Invest Oy | Financial services | 2022 |
| Lelu- ja Paperitukku Pentti Kekola Ky | Wholesale & retail | 1985 |
| Lemmikkihotelli Doggies & Kitties Oy | Other services | 2016 |
| Leos Oy | Professional & scientific | 1991 |
| Levi Arctic Lux Oy | Real estate | 1980 |
| Levi Star West Oy | Real estate | 2023 |
| Levymarkkinointi Ky Markus Ruohonen | Wholesale & retail | 1986 |
| Lexfin Oy | Professional & scientific | 2014 |
| Life Circus Oy | Arts & recreation | 2021 |
| Liiditehdas Oy | Professional & scientific | 2022 |
| Liikennekoulu Rinki Oy | Education | 2007 |
| Liikguu Group Oy | Education | 2019 |
| Lilja Asuntovuokraus Oy | Real estate | 2023 |
| Linja-Viitala Ky | Information & communication | 1984 |
| Lite bättre Consulting Company Oy | Professional & scientific | 2021 |
| Logirak Oy | Professional & scientific | 2019 |
| Logistics O. Nuottajärvi Oy | Transport & logistics | 1995 |
| Loisto voimavarapalvelut Oy | Education | 2020 |
| Loistotila Oy | Health & social care | 2017 |
| Loota Music Oy | Manufacturing | 2017 |
| Los Piilos Oy | Real estate | 1999 |
| Loud'n Live Promotions Oy Ltd. | Professional & scientific | 2009 |
| Low and Loud Oy | Wholesale & retail | 2020 |
| Luckiefun Pitäjänmäki Oy | Hospitality | 2015 |
| Ludio Oy | Financial services | 1990 |
| Luentokeskus Alexis Oy | Education | 2022 |
| Lumifund Oy | Financial services | 2019 |
| Lumikko Huoltopalvelut Oy | Manufacturing | 1991 |
| Lumikko Oy | Manufacturing | 1989 |
| Lumimiehet Ky | Administrative & support | 1988 |
| Lumivaara Partners Oy | Professional & scientific | 2022 |
| Luomassa Oy | Professional & scientific | 2022 |
| Luottotimpurit Oy | Construction | 2021 |
| Luova Kaniini Oy | Professional & scientific | 2023 |
| Luova Tehdas Oy | Arts & recreation | 2013 |
| Luova toimisto Huomenna Oy | Professional & scientific | 2023 |
| Lvi-insinööritoimisto J. Saastamoinen Oy | Professional & scientific | 2015 |
| Lähettilakeus Oy | Transport & logistics | 1993 |
| LähiTapiola Etelä-Pohjanmaa Keskinäinen Vakuutusyhtiö | Financial services | 1936 |
| Lähikodit Oy | Real estate | 2017 |
| Lähiteräs Oy | Manufacturing | 2023 |
| Lännen Autokatsastus Oy | Professional & scientific | 1996 |
| Lännen Katsastus Oy | Professional & scientific | 2020 |
| Lännen Maalämpö Oy | Construction | 2014 |
| Lännen Media Oy | Information & communication | 2014 |
| Länsi-Kate Oy | Construction | 1975 |
| Länsi-Suomen Laitehuolto Oy | Manufacturing | 1993 |
| Länsi-Suomen Värjärit Oy | Wholesale & retail | 1998 |
| LänsiTukku Oy | Wholesale & retail | 2023 |
| Lääkäripalvelu AKL Oy | Health & social care | 2009 |
| Lääkäripalvelu Tavast Oy | Health & social care | 2009 |
| Lääkäripalvelu Tiina Leppänen Oy | Health & social care | 2023 |
| Lääkäripalvelut Pirjo Lampinen Oy | Health & social care | 2004 |
| Lääkäripalvelut Vanhatalo Oy | Health & social care | 2026 |
| Löyty Digital Oy | Information & communication | 2026 |
| M Raksa Ky | Construction | 2011 |
| M Raksa Service Oy | Construction | 2024 |
| M-Maxicar Ky | Construction | 2000 |
| M-Trahteeri Oy | Hospitality | 1994 |
| M. Etelämäki Oy | Transport & logistics | 2022 |
| M. Luoma Oy | Wholesale & retail | 1992 |
| M. Varpuluoma Ky | Transport & logistics | 1988 |
| M. ja H. Rintamäki Oy | Agriculture & fishing | 1989 |
| M2 Projects Oy | Real estate | 2022 |
| MEDIMIS Oy | Financial services | 2009 |
| Mica Technology OY Ltd | Wholesale & retail | 2007 |
| MJ Katajamäki Avoin yhtiö | Transport & logistics | 2011 |
| MK Group Oy | Wholesale & retail | 2021 |
| MKL Invest Oy | Real estate | 2008 |
| MKMM Management Oy | Professional & scientific | 2024 |
| MM Laatuasunnot Oy | Construction | 2013 |