| Sarjalainen Oy | Information & communication | 2026 |
| Seipu Invest Oy | Financial services | 1983 |
| Seira Oy | Construction | 2026 |
| Seppo Lahdensuo Oy | Construction | 1990 |
| Seppälän Autosähkö Oy | Other services | 1996 |
| Sib Advice LKV Oy | Real estate | 2020 |
| Siipimäki Oy | Agriculture & fishing | 2025 |
| Siivouspalvelut Vainionpää Oy | Other services | 2019 |
| Sikatiimi Oy | Agriculture & fishing | 2001 |
| Silene Kauppa Oy | Wholesale & retail | 2026 |
| Silver Way Oy | Wholesale & retail | 2010 |
| Simpsiönhuippu Oy | Real estate | 1989 |
| Simpsiönvuori Oy | Administrative & support | 1985 |
| Sirius Safir Avoin yhtiö | Wholesale & retail | 1994 |
| Sorkkarauta & Pojat Oy | Real estate | 2021 |
| Sototek Oy | Transport & logistics | 2010 |
| SoundCom Oy | Arts & recreation | 2009 |
| Sparlem Oy | Professional & scientific | 2022 |
| Sparrari Oy | Wholesale & retail | 2016 |
| SteelSet Oy | Manufacturing | 2023 |
| Steelberry Invest Oy | Financial services | 2019 |
| Style Academy Oy | Other services | 2016 |
| Success Innovation Oy | Professional & scientific | 2012 |
| Succession Group Oy | Real estate | 2003 |
| Sundee Ky | Manufacturing | 1985 |
| Suokon Kuivaimupalvelu Oy | Water & waste | 2012 |
| Suokon Lokapalvelu Oy | Water & waste | 2005 |
| Suokot Oy | Construction | 2004 |
| Suomen Aitta ja Tupa Oy | Construction | 1983 |
| Suomen Ammattiakatemia Oy | Education | 2013 |
| Suomen Hiomopalvelu Antelo & Järviluoma | Manufacturing | 1998 |
| Suomen Hitsauspalvelu Oy | Manufacturing | 2009 |
| Suomen Paperilanka Oy | Manufacturing | 1993 |
| Suomen Purkuekspertit Oy | Construction | 2012 |
| Suomen Radiobooking Oy | Professional & scientific | 2001 |
| Suomen Tehoimurointi Oy | Water & waste | 2019 |
| Suomen manuaaliterapiakeskus SPINAL Oy | Health & social care | 2023 |
| Suomenselän matkailukeskus Ky | | 1990 |
| Syväoja Oy | Real estate | 1967 |
| Syväojan Kiinteistö Oy | Real estate | 1977 |
| Sähköasennukset Kosonen Oy | Construction | 2018 |
| Sähköasennus Matti Koivisto Ky | Construction | 1991 |
| Sähköasennus Sipilä Oy | Construction | 2016 |
| Sähköbetoni K&A Oy | Manufacturing | 1986 |
| T-Market Oiva Koskela Ky | Wholesale & retail | 1983 |
| T-Sound Ky | Information & communication | 1991 |
| Tarjoushakusuomi OY | Information & communication | 2016 |
| TJ Accounting & Consulting Oy Ltd | Professional & scientific | 2019 |
| TNR-Cars Avoin yhtiö | Wholesale & retail | 2013 |
| Tai Hovi Ky | Hospitality | 2020 |
| Taimis Oy | Agriculture & fishing | 2026 |
| Taisto Pusa Oy | Construction | 2015 |
| Takaluomat Oy | Wholesale & retail | 1996 |
| Taksipalvelu Marko Rajamäki Ky | Transport & logistics | 2007 |
| Talentman Oy | Professional & scientific | 2009 |
| Talotekniikka Timonen Oy | Construction | 2019 |
| Tampparin Vesiosuuskunta | Water & waste | 1968 |
| Tasoket Oy | Construction | 2025 |
| Tawan Rungrood Ky | Hospitality | 2012 |
| Taxidermy Art Ky | Manufacturing | 1992 |
| Team Glory Oy | Agriculture & fishing | 2016 |
| Team Penttilä Oy | Manufacturing | 2000 |
| Tech Media Oy | Professional & scientific | 2009 |
| Tehotec Oy | Professional & scientific | 2017 |
| Telaketju avoin yhtiö | Professional & scientific | 2002 |
| Thermopolis Oy | Professional & scientific | 2006 |
| Tig Steel Oy | Manufacturing | 2025 |
| Tiitun Autosähkötarvike Ky | Wholesale & retail | 1990 |
| Tili ja Sisustus Annastiina Oy | Wholesale & retail | 1992 |
| Tili-Annala Oy | Professional & scientific | 2023 |
| TiliTilda Oy | Professional & scientific | 2019 |
| Tomassus Oy | Construction | 2008 |
| Tooltek Oy | Manufacturing | 2024 |
| Top-Magu Oy | Wholesale & retail | 2009 |
| Track Murskaus Kangas Oy | Construction | 2007 |
| Trading Circle Oy | Wholesale & retail | 1991 |
| Traktorihuolto Matti Kulmala Ky | Manufacturing | 2011 |
| Tuotanto J. Mäkelä Oy | Manufacturing | 1989 |
| Tuovil Oy | Professional & scientific | 2022 |
| Turjan Turkistarha Oy | Agriculture & fishing | 1996 |
| Turvapuhelu Suomi Oy | Other services | 2022 |
| Tuumiva oy | Health & social care | 2023 |
| Ulvila Capital Oy | Financial services | 2025 |
| Uranus-Tuonti Oy | Wholesale & retail | 1985 |
| Uudenmaan Viemärisukitus, UVS Oy | Construction | 2014 |
| V.J. Peltola Ky | Construction | 2009 |
| VBE Oy | Agriculture & fishing | 2026 |
| VSI-Kiinteistöt Oy | Real estate | 2006 |
| VUORENMAA Yhtiöt Oy | Wholesale & retail | 1987 |
| Valoki Oy | Real estate | 2023 |
| Valomonsteri Oy | Wholesale & retail | 2012 |
| Veerant Finland Oy | Wholesale & retail | 1998 |
| Vehkon Oy | Construction | 2007 |
| Vehkon Sijoitus Oy | Financial services | 2007 |
| Veljekset Lahdensuo Oy | Manufacturing | 2024 |
| Veljekset Suutala Oy | Construction | 2015 |
| Vemar Oy | Real estate | 2018 |
| Veracap Oy | Wholesale & retail | 1998 |
| Vesala Invest Oy | Real estate | 2022 |
| Vesitaloussuunnittelu Hangasmaa Ky | Professional & scientific | 2024 |