| Lehmus Labs Oy | Information & communication | 2025 |
| Lehmus Roastery Oy | Manufacturing | 2016 |
| Lehmus Works Oy | Construction | 2025 |
| Leija-Pojat Kiteboys Finland Ky | Manufacturing | 1999 |
| Leino Consulting Oy | Professional & scientific | 2007 |
| Leipomo Petäjä Ky | Manufacturing | 2005 |
| Leksan Urakointi Oy | Construction | 2021 |
| Lemartti Oy | Real estate | 1992 |
| Lemetti Terveydenpalvelut Oy | Health & social care | 2025 |
| Lemmikkitarvike Posi Oy | Wholesale & retail | 2022 |
| Leninkiliike Vilma Ky | Wholesale & retail | 1966 |
| Lentävä Joutsen Oy | Real estate | 2009 |
| LetDo Capital Oy | Real estate | 2018 |
| Levandofin Oy | Wholesale & retail | 2022 |
| Levi Capital Oy | Financial services | 2008 |
| LiardoCars Oy | Wholesale & retail | 2024 |
| Life4seasons Oy | Agriculture & fishing | 2025 |
| Liiga-Saipa Oy | Arts & recreation | 2000 |
| Liikunta-Origo Oy | Health & social care | 2010 |
| Lilianne Ky | Hospitality | 1997 |
| Lime Ravintolat Oy | Hospitality | 2024 |
| LinHea OY | Hospitality | 2025 |
| Lindan Luomukauppa Ky | Wholesale & retail | 2015 |
| Lindh Consulting Oy | Wholesale & retail | 2012 |
| Lindqvist Oy Lintec | Manufacturing | 1987 |
| Linen Sky Oy | Wholesale & retail | 2013 |
| Lingos oy | Households | 2017 |
| Linnavuoren Yrityspalvelut Oy | Professional & scientific | 2017 |
| Linnoituksen Pitopalvelu Oy | Hospitality | 2015 |
| Lippestep Oy | Professional & scientific | 1998 |
| Lisäpalvelu Lappeenranta Oy | Administrative & support | 2019 |
| Lisäpalvelu Savo Oy | Administrative & support | 2024 |
| Lisäpalvelu Teollisuus LPF Oy | Administrative & support | 2019 |
| Lisäpalvelu Welding & Industry Oy | Administrative & support | 2025 |
| Litmala Group Oy | Professional & scientific | 2017 |
| LivInvest Oy | Financial services | 2023 |
| Loime Oy | Professional & scientific | 1989 |
| Loma-Oksa Oy | Hospitality | 1989 |
| Louhinta-Pekki Ky | Construction | 1984 |
| Lounas-Kahvila Lemon avoin yhtiö | Hospitality | 2005 |
| Lounaskahvila El'si Ky | Hospitality | 2006 |
| Lounasravintola Kapteeninkulma Oy | Hospitality | 1997 |
| Lpr Invest Oy | Real estate | 2017 |
| Lpr-Dorado Oy | Hospitality | 1988 |
| Lprint Oy | Manufacturing | 2022 |
| Luiska-Nikuri Oy | Construction | 1988 |
| Lujuus Oy | Professional & scientific | 2020 |
| Luokosm Oy | Professional & scientific | 2024 |
| Luomma plus Oy | Wholesale & retail | 2007 |
| Luontaishoitola Marja-Liisa Harri Oy | Health & social care | 2008 |
| Luontos Ky | Health & social care | 2005 |
| Luostarinen Racing Oy | Other services | 2021 |
| Luotto LKV Oy | Real estate | 2024 |
| Luova Sähkö Oy | Construction | 2014 |
| Luova Tuho Oy | Professional & scientific | 2024 |
| Luukkaan Automaalaamo Oy | Other services | 2014 |
| Luumäen Puu Oy | Manufacturing | 2013 |
| Luumäen kiinteistökehitys Oy | Hospitality | 2011 |
| Luxio Oy | Construction | 2017 |
| Lysti Lyyli Oy | Wholesale & retail | 2026 |
| Lämmin Tuuli OY | Wholesale & retail | 2011 |
| LähdeMies Oy | Health & social care | 2012 |
| LähiTapiola Kaakkois-Suomi Keskinäinen Vakuutusyhtiö | Financial services | 1941 |
| Lätkä Lentää Oy | Arts & recreation | 2024 |
| Lääkäriasema DokTori Oy | Health & social care | 2014 |
| Lääkäripalvelu Juha Romppanen Oy | Health & social care | 2007 |
| M Heinänen Oy | Real estate | 1982 |
| M&J Autot Oy | Wholesale & retail | 2023 |
| M. Korhonen Oy | Real estate | 1963 |
| M. Penttilä Oy | Real estate | 2018 |
| M. Tauriainen Oy | Real estate | 2023 |
| M. Valkonen Oy | Construction | 2008 |
| M.P CarCare Oy | Other services | 2023 |
| M.Värtö Oy | Construction | 2008 |
| M3H Investment Oy | Professional & scientific | 2019 |
| MAF Holding Oy | Financial services | 2025 |
| MAI Finland Oy | Health & social care | 2024 |
| Mashhad OY | Hospitality | 2023 |
| MD- Group Oy | Real estate | 1996 |
| ME-Kuljetus Oy | Transport & logistics | 2014 |
| MH Pipeworks OY | Manufacturing | 2019 |
| MJ Enterprise Oy | Hospitality | 2025 |
| MJ-Projektit Oy | Construction | 2022 |
| MJH Holdings Oy | Financial services | 2026 |
| MJS-Logistiikkatalo Oy | Real estate | 2008 |
| MJV-Huolto Oy | Other services | 2020 |
| MKO rakennus oy | Construction | 2026 |
| MMK-Kuljetus Oy | Transport & logistics | 2002 |
| MMK-Power Oy | Other services | 2015 |
| MMS Logistics Oy | Transport & logistics | 2013 |
| MN-Design Oy | Wholesale & retail | 1992 |
| MP Performance Solutions Oy | Arts & recreation | 2016 |
| MPR Koti Oy | Wholesale & retail | 2026 |
| MPTT Consulting Oy | Professional & scientific | 2021 |
| MRM Productions Oy | Education | 2022 |
| MS-Vuokraus Oy | Administrative & support | 2011 |
| MSF-Sijoitus Oy | Wholesale & retail | 1966 |
| MSLine Oy | Transport & logistics | 2015 |
| MSP-Investment Oy | Wholesale & retail | 2016 |
| MSS-hammas Oy | Health & social care | 2017 |