| Sale Kaivaa Oy | Construction | 2018 |
| Salelinna ky | Wholesale & retail | 2012 |
| Salla Salmela Oy | Wholesale & retail | 2001 |
| Salmi Kaivin Oy | Construction | 2010 |
| Salon Korjaamo Oy | Other services | 1989 |
| Salumägi Laatoitus Oy | Construction | 2025 |
| Salusleiri Oy | Real estate | 2026 |
| Sammalisto Oy | Construction | 1956 |
| Sampolan Rengaspaja Oy | Wholesale & retail | 2020 |
| Saneeraus Koivisto Oy | Construction | 2007 |
| Saneeraus Ovaska Oy | Construction | 2021 |
| Sanes Oy | Real estate | 1994 |
| Selko Solutions Oy | Information & communication | 2026 |
| Seulapuiston Kioski avoin yhtiö | Wholesale & retail | 1993 |
| Seunia Oy | Wholesale & retail | 2008 |
| SewTek Oy | Manufacturing | 2024 |
| SiBe Work Oy | Construction | 2020 |
| Sijoitusyhtiö Mika Hartikainen Oy | Financial services | 1988 |
| Silexi Oy | Administrative & support | 2023 |
| Silly Vision Oy | Information & communication | 2021 |
| Silta-Tex Anneli Siltaniemi Kommandiittiyhtiö | Wholesale & retail | 1976 |
| Simtrans Ky | Transport & logistics | 2011 |
| Sininiitty Management Oy | Professional & scientific | 2020 |
| Sipilän Varakoti Oy | Real estate | 1997 |
| Sipitaso Oy | Real estate | 2008 |
| Siraco Oy | Construction | 2020 |
| Siril Oy | Wholesale & retail | 2019 |
| Sisustuslaatikot T.K Oy | Manufacturing | 2019 |
| SmartPharma Finland Oy | Professional & scientific | 2026 |
| SoftMagic Oy | Information & communication | 2003 |
| Solaudio Oy | Manufacturing | 2006 |
| Solute Oy | Information & communication | 2006 |
| Sopuli Oy | Arts & recreation | 2026 |
| Sorto Invest OY | Real estate | 2017 |
| Sortuma Oy | Construction | 2014 |
| Speweld Service Oy | Manufacturing | 2009 |
| Sport24seven International Finland Oy | Arts & recreation | 2019 |
| Starminds Academy Oy | Professional & scientific | 2025 |
| Stemet Oy | Manufacturing | 2012 |
| Stopteltat Oy | Administrative & support | 2002 |
| Studio Us By Design Oy | Professional & scientific | 2025 |
| Success Consulting Oy | Administrative & support | 2017 |
| Suikka Oy | Manufacturing | 2006 |
| Suomen Asiakaspalvelu Oy | Information & communication | 2009 |
| Suomen Autopuhdistus Ky | Other services | 1989 |
| Suomen Liikunta-apteekki Oy | Health & social care | 2014 |
| Suomen Lämpölinja Oy | Construction | 1992 |
| Suomen Mainosmobiilit Oy | Wholesale & retail | 1993 |
| Suomen Nukliditekniikka Oy | Water & waste | 2019 |
| Suomen Parvekecenter Oy | Construction | 2025 |
| Suopellon Lomarakenne Oy | Construction | 1990 |
| Suunnittelutoimisto Ready Ky | Professional & scientific | 2001 |
| Suvex Oy | Wholesale & retail | 1981 |
| Suvi Perttunen Oy | Arts & recreation | 2022 |
| Synergy Partners Finland Oy | Professional & scientific | 2010 |
| Sähköasennus Olin & Tuomiset Oy | Construction | 1980 |
| Sähkömestari Frisk Oy | Construction | 2022 |
| Sähköpalvelu Patokoski Oy | Construction | 2015 |
| Sälpäkivi Holdings Oy | Professional & scientific | 2026 |
| Sätera Oy | Construction | 2012 |
| T-kok Oy | Other services | 2023 |
| T. Siira Oy | Wholesale & retail | 2011 |
| THETHI Oy | Hospitality | 2015 |
| TJO-Tekniikka Oy | Wholesale & retail | 2000 |
| TK-Contents Oy | Other services | 1998 |
| TMT Kuljetus Oy | Transport & logistics | 2018 |
| TN Liikenne Oy | Transport & logistics | 2002 |
| Tph-Rakennus OY | Construction | 2019 |
| TS Rakennuskonsultointi Oy | Professional & scientific | 2022 |
| TTJ Rakentajat Oy | Construction | 1995 |
| Talli Bäng Bäng Oy | Agriculture & fishing | 2024 |
| Tameka Oy | Real estate | 2013 |
| Tamurak Oy | Construction | 2019 |
| Tapio Rikala Ky | Real estate | 1988 |
| Tarmola MultiTrades Oy | Construction | 2026 |
| Tatlog Oy | Transport & logistics | 2022 |
| Tavori Oy | Wholesale & retail | 1992 |
| Tawemec Service Oy | Manufacturing | 2018 |
| Teemapuu Oy | Agriculture & fishing | 1999 |
| Tekstipuu Ky | Professional & scientific | 2010 |
| Tendac Oy | Wholesale & retail | 2002 |
| Teratili Ky | Professional & scientific | 1991 |
| Tili ja Kiinteistö Erik Huju Oy | Professional & scientific | 1966 |
| Tiliekspertti M. Vink Oy | Professional & scientific | 1994 |
| Tilintarkastus Kuosa-Kaartti Oy | Professional & scientific | 2014 |
| Tiliporras Päijät-Häme Oy | Professional & scientific | 2025 |
| Tilitoimisto Tulospuu Oy | Professional & scientific | 2007 |
| Timantti- ja purkutyö Teräväinen Oy | Construction | 2016 |
| Tolmas Oy | Professional & scientific | 2014 |
| Topi Invest Oy | Wholesale & retail | 1976 |
| Trailerikeskus Siikala Oy | Wholesale & retail | 2011 |
| Trusted Investing Oy | Professional & scientific | 2024 |
| Tumerak Oy | Construction | 2022 |
| Tuohenmaa Palvelut Oy | Administrative & support | 1992 |
| Unicorn Guns Oy | Manufacturing | 2021 |
| Uudenmaan Tuotemarkkinointi Oy | Construction | 1989 |
| V & U Salmenius Ky | Wholesale & retail | 1985 |
| VL Sales Oy | Professional & scientific | 2026 |
| VMPRINT Oy | Manufacturing | 2026 |
| VSS Ilmastointi Oy | Construction | 2024 |