| Kuljetus Oy Markku Sirén | Transport & logistics | 1982 |
| Kuljetus Virtanen & Tenhu Oy | Transport & logistics | 1994 |
| Kuljetus onmik Oy | Transport & logistics | 2026 |
| Kuljetusliike H. Tuhkanen Oy | Transport & logistics | 1991 |
| Kuljetusliike P. Skog Oy | Transport & logistics | 2001 |
| Kuljetusliike T. Kulo & Kumpp | Transport & logistics | 1961 |
| Kuljetusliike Toivanen Oy | Transport & logistics | 2004 |
| Kuljetuspalvelu Pohjoissalo Ky | Transport & logistics | 2007 |
| Kulkutie Oy | Wholesale & retail | 2025 |
| Kulmakonditoria Kerava Ky | Hospitality | 2015 |
| Kultalippu Oy | Arts & recreation | 2016 |
| Kuplawohveli Kinuski Oy | Professional & scientific | 2025 |
| Kupru Oy | Administrative & support | 2026 |
| Kustannusosakeyhtiö Gogam | Information & communication | 2024 |
| Kutse Oy | Construction | 2015 |
| Kuuselan Metsä Oy | Agriculture & fishing | 2012 |
| Kylmäkide Oy | Other services | 1994 |
| Kyläkiito Oy | Transport & logistics | 2025 |
| Kymppikaide Oy | Manufacturing | 2021 |
| Kyykkyliike Oy | Professional & scientific | 2020 |
| L Plastic Oy | Manufacturing | 1996 |
| L&R Tuusula Oy | Hospitality | 2023 |
| LEDISOL Oy | Professional & scientific | 2009 |
| LEKSAGOR Oy | Construction | 2021 |
| LK Systems OY | Construction | 2008 |
| LL Office Oy | Professional & scientific | 2023 |
| LM Huolto Oy | Administrative & support | 1997 |
| LM-Laatutuote Avoin Yhtiö | Wholesale & retail | 1995 |
| LND-bros Oy | Real estate | 2022 |
| LOIVA LASKU Oy | Real estate | 2004 |
| Lover Boy OY | Arts & recreation | 2015 |
| LVA Ilmastointi Oy | Construction | 1989 |
| LVI - E. Uusimaa Oy | Construction | 2000 |
| LVI-HeMi Oy | Construction | 2013 |
| LVI-Inset Oy | Professional & scientific | 1989 |
| Lvi-Joltek OY | Construction | 2012 |
| LVIS-Insinööritoimisto Timo Vättö Oy | Professional & scientific | 1996 |
| LYXRA Oy | Information & communication | 2026 |
| LaKo Trade Oy | Wholesale & retail | 2006 |
| LaNa Beauty House Oy | Other services | 2021 |
| Laastilinja Oy | Construction | 1997 |
| Laatuhitsaus Maunula Oy | Manufacturing | 2022 |
| Laatuisännöinti Oy Marttila | Real estate | 1989 |
| Laatutimpurit Oy | Construction | 2020 |
| LagunaGroup Oy | Education | 2025 |
| Lahden Kipupiste Oy | Health & social care | 1993 |
| Laiteklinikka Oy Ab | Other services | 2024 |
| Laitella Oy | Real estate | 2023 |
| Laitella Rakennus Oy | Construction | 2026 |
| Lakiasiaintoimisto Haminan Lakiapu Oy | Professional & scientific | 2018 |
| Lakiasiaintoimisto JLM Immonen Oy | Professional & scientific | 1998 |
| Lakiasiaintoimisto Matti Matikka Oy | Professional & scientific | 1999 |
| Lakiasiaintoimisto Pekka Väyrynen Oy | Professional & scientific | 1988 |
| Lakiasiaintoimisto Tuominen Oy | Professional & scientific | 2019 |
| Lakiasiat Kalle Hytönen Oy | Professional & scientific | 2020 |
| Lakipalvelu Ville Hoikkala Oy | Professional & scientific | 2025 |
| Lancetta Oy | Wholesale & retail | 1991 |
| Langskip Energy Nordic Oy | Wholesale & retail | 2018 |
| Laokoon Oy | Financial services | 2025 |
| Lapin Rakennus- ja henkilövuokrauskeskus Oy | Construction | 1991 |
| Lareon Oy | Wholesale & retail | 2025 |
| Lasoon Oy | Hospitality | 2025 |
| Lastensuojelu- ja tukipalvelut Keidas Oy | Health & social care | 2008 |
| Lastmile Connection Service - LMCS Oy | Wholesale & retail | 1996 |
| Lastukasa Oy | Wholesale & retail | 2025 |
| Latausloki Oy | Information & communication | 2025 |
| Lattianpäällystys H&P Pieviläinen Ky | Construction | 2011 |
| LauHe Oy | Health & social care | 2020 |
| Laufor Oy | Wholesale & retail | 2023 |
| Launear Oy | Transport & logistics | 2015 |
| Laureila Ky | | 1981 |
| Lauri Mielonen Ky | Administrative & support | 2014 |
| Lautmetalli Oy | Construction | 1980 |
| Lavabox Oy | Wholesale & retail | 1993 |
| LeK-PeT Ky | Construction | 2004 |
| Lean Thinking Oy | Professional & scientific | 2021 |
| Legal and Commercial PE Oy | Financial services | 2012 |
| Lehtipalvelu Eeva Alatalo Oy | Wholesale & retail | 1988 |
| Leikoski Oy | Financial services | 1976 |
| Leo Koskinen Oy | Manufacturing | 1974 |
| Leome Oy | Health & social care | 2018 |
| Les Grandes Oy | Wholesale & retail | 1992 |
| Letkis Oy | Professional & scientific | 1989 |
| Levonmäen Taksi Oy | Transport & logistics | 2020 |
| Lexo Oy | Construction | 2019 |
| Liikuntakeskus PompIT Oy | Education | 2011 |
| Liikuntapalvelut Keppi & Porkkana Oy | Education | 2019 |
| Linder SPR OY | Construction | 2021 |
| Lindram Oy | Construction | 2015 |
| Lintusetti Oy | Wholesale & retail | 2016 |
| Liolda Oy | Financial services | 1991 |
| Lion Lashes Oy | Other services | 2016 |
| Lisnel Oy | Hospitality | 2021 |
| Little Nepal Oy | Hospitality | 2019 |
| Living Invest Oy | Financial services | 2021 |
| Loco Rakennus Oy | Construction | 2019 |
| Logisticshouse Oy | Transport & logistics | 2017 |
| Logistiikkapalvelut Jocama Oy | Transport & logistics | 2017 |
| Loisirs Oy | Wholesale & retail | 1992 |
| Loistaa Consulting Oy | Education | 2017 |