| Kiint. Oy Lamminkatu 7 | Real estate | 1989 |
| Kiinteistö Myntt Oy | Financial services | 2025 |
| Kiinteistö Oy Isomallimestari | Real estate | 2021 |
| Kiinteistö Oy Jahtipaikoitus | Real estate | 2004 |
| Kiinteistö Oy Kaarinan Asianajajankatu 3 | Real estate | 2010 |
| Kiinteistö Oy Kaarinan Hallimestarinkatu 26 | Real estate | 2022 |
| Kiinteistö Oy Kaarinan Kauppakeskus | Real estate | 1988 |
| Kiinteistö Oy Kaarinan Kivitokeenkatu 4 | Real estate | 2008 |
| Kiinteistö Oy Kaarinan Laarikatu | Real estate | 2005 |
| Kiinteistö Oy Kaarinan Vuokratalot | Real estate | 1993 |
| Kiinteistö Oy Kaislahdenkatu 6 | Real estate | 2018 |
| Kiinteistö Oy Katariinantie | Real estate | 1973 |
| Kiinteistö Oy Krossinriuku | Real estate | 2017 |
| Kiinteistö Oy Liedon Avantin Robotti | Real estate | 2023 |
| Kiinteistö Oy Marielund | Real estate | 2007 |
| Kiinteistö Oy Nagu Byskär | Real estate | 2012 |
| Kiinteistö Oy Papinsalmen Sauna Laituri | Real estate | 2005 |
| Kiinteistö Oy Pikkumallimestari | Real estate | 2021 |
| Kiinteistö Oy Tilli Kiinteistöt | Real estate | 2013 |
| Kiinteistö Oy Turun Valokaari | Real estate | 1994 |
| Kiinteistö Oy Vanhuudenturva | Real estate | 2000 |
| Kiinteistö Oy Villa Laguna | Real estate | 2008 |
| Kiinteistö Paroni Oy | Construction | 2002 |
| Kiinteistöyhtiö Ardante Oy | Administrative & support | 1995 |
| Kirjanpitopalvelu Päivi Lindroos Oy | Professional & scientific | 2020 |
| Kiulu Company | Professional & scientific | 2022 |
| Kodian Guitars Oy | Manufacturing | 2019 |
| Kodinpaikka Oy | Real estate | 2024 |
| Koli Invest Oy | Real estate | 1988 |
| Kone-Cator Oy | Administrative & support | 1993 |
| Kone-Lammi Cator Oy | Wholesale & retail | 1989 |
| Konsultkompaniet Oy Ab | Financial services | 2025 |
| Korjaamo J&J Kaarina Oy | Other services | 2018 |
| Korttelin 5014 Autopaikoitus Oy | Real estate | 1979 |
| Kotivesi Suomi Oy | Construction | 1995 |
| Krossin Autokorjaamo Oy | Other services | 2024 |
| Krossin Katsastus Oy | Professional & scientific | 2014 |
| Krossin Leipomokiinteistö Oy | Real estate | 1994 |
| Kuja Installation Oy | Other services | 2022 |
| Kuja Media Oy | Manufacturing | 2011 |
| Kuljetus Jelo Oy | Transport & logistics | 2021 |
| Kuljetus K-Mikko Oy | Transport & logistics | 2025 |
| Kuljetusliike A. Lindberg Oy | Transport & logistics | 1994 |
| Kuljetusliike Gunn Oy | Transport & logistics | 1983 |
| Kuljetusliike Jorma Sirviö Oy | Transport & logistics | 1984 |
| Kultaseppä Kimmo Miettinen Ky | Wholesale & retail | 1991 |
| KumRok Oy | Wholesale & retail | 2013 |
| Kustannus Oy Culturamed | Real estate | 1982 |
| Kustannusosakeyhtiö Lehmus | Information & communication | 1960 |
| Kylmälä Oy | Wholesale & retail | 1977 |
| Kymitore Oy | Information & communication | 2012 |
| Kärki Kumppanit Oy | Professional & scientific | 2024 |
| L Vigelius Oy | Information & communication | 2000 |
| L&Z Service Oy | Construction | 2020 |
| L. Laaksonen Oy | Real estate | 2005 |
| LK Prowelding Oy | Manufacturing | 2022 |
| LKV Arvo Oy | Real estate | 2019 |
| LVI - taito Oy | Professional & scientific | 1979 |
| LVI Leijona Oy | Construction | 2023 |
| Lvi-Haverinen OY | Construction | 2014 |
| Labmaster Oy | Manufacturing | 1985 |
| Lakitoimisto Ewart Ky | Professional & scientific | 1994 |
| Lassila Juridia Oy | Real estate | 2023 |
| Lasten Liikennekoulu Oy | Education | 2008 |
| Lasten Seesam Kaarina Oy | Wholesale & retail | 2012 |
| Laxal Oy | Construction | 1990 |
| Lea Talo Oy | Arts & recreation | 2019 |
| Legit Coaching Oy | Professional & scientific | 2024 |
| Lehtech Oy | Manufacturing | 2010 |
| Leipomo Krossi Oy | Manufacturing | 2016 |
| Leipomo Sanni ja konditoria Marleena Ky | Manufacturing | 1989 |
| Lenholm Holding Oy | Financial services | 2020 |
| Lesjöfors Springs Oy | Wholesale & retail | 1974 |
| Liedon Vesi ja Lämpö Oy | Construction | 1980 |
| Lifekit Oy | Health & social care | 2020 |
| Lightpress Group Oy | Manufacturing | 2020 |
| Lightpress Oy | Manufacturing | 2013 |
| Lightpress-Kiinteistöt Oy | Real estate | 2013 |
| Lightron Kommandiittiyhtiö | Wholesale & retail | 1987 |
| Lihaliike Reino Jokinen Oy | Wholesale & retail | 1980 |
| Liikuntapalvelukeskus Superfysio Oy | Health & social care | 1989 |
| Lilla Persson Oy | Professional & scientific | 2024 |
| LineDeck Oy | Wholesale & retail | 2016 |
| Lintu Netsales Oy | Wholesale & retail | 2019 |
| Lisälaite kommandiittiyhtiö, Tapani Iivonen | Wholesale & retail | 1975 |
| Loco Players Oy | Professional & scientific | 2011 |
| Logmill Oy | Professional & scientific | 2010 |
| Loma Måsa Oy | Hospitality | 1995 |
| Longsummer Invest Oy | Financial services | 2023 |
| Lounais-Suomen Puunhoito Oy | Other services | 2018 |
| Lounais-Suomen talousohjaus Oy | Professional & scientific | 2021 |
| LounasBistro Oy | Hospitality | 2026 |
| Ludibrium Oy | Manufacturing | 2011 |
| Lujama Avoin yhtiö | Construction | 1982 |
| Luonnonvirta Oy | Construction | 2015 |
| LuxMotor Kaarina Oy | Other services | 2025 |
| Länkikadun Huolto Oy | Energy | 1987 |
| Länsikodit Oy | Wholesale & retail | 2009 |
| Lääkäripalvelut Antti Jussila Oy | Health & social care | 2024 |
| Mansikkamaa Innovations OY | Professional & scientific | 2015 |