| Sovector Oy | Information & communication | 2011 |
| Sport Mimi Oy | Arts & recreation | 2018 |
| Spotox Oy | Wholesale & retail | 2006 |
| StarTours Oy | Administrative & support | 2012 |
| Starship X Oy | Manufacturing | 2023 |
| Stolt Capital Oy | Construction | 2023 |
| Stoneplan Oy | Professional & scientific | 2013 |
| Strategic Scientific Consulting Finland Oy | Professional & scientific | 2015 |
| Stratton & Oakmont Holding Oy | Wholesale & retail | 2022 |
| Stromaxx Oy | Construction | 2019 |
| Studio Karin Kukka Oy | Professional & scientific | 2014 |
| Studio SightHound Oy | Professional & scientific | 2023 |
| Suikkix Oy | Hospitality | 2024 |
| Sule3D-kartoitus oy | Professional & scientific | 2021 |
| Sumarab Oy | Arts & recreation | 1986 |
| Sumo Sushi Oy | Hospitality | 2025 |
| Sumu Records Oy | Information & communication | 2003 |
| Suomen Autohalli.com Oy | Wholesale & retail | 2019 |
| Suomen Biokiertotuote Oy | Manufacturing | 2016 |
| Suomen Henkilöstöleasing Ky | Administrative & support | 2024 |
| Suomen Idea Korut Oy | Manufacturing | 1989 |
| Suomen Kattopinta Oy | Construction | 2021 |
| Suomen Kuulosuojaus Oy | Wholesale & retail | 2013 |
| Suomen Lukkokauppa Oy | Wholesale & retail | 2008 |
| Suomen Myyntivaunut Hot and Cold Oy | Hospitality | 2025 |
| Suomen Nettipakkaus Oy | Wholesale & retail | 2011 |
| Suomen Patentti-insinööripalvelu Oy | Professional & scientific | 2012 |
| Suomen Pintapalvelu Oy | Administrative & support | 2022 |
| Suomen Pumppaamohuollot Oy | Water & waste | 2016 |
| Suomen Pumppaamopalvelut Oy | Water & waste | 2021 |
| Suomen Santiko Oy | Financial services | 2016 |
| Suomen Seinät Oy | Construction | 1993 |
| Suomen Sähköasennus Oy | Construction | 2002 |
| Suomen TyöllisyysOte Oy | Health & social care | 2024 |
| Suomen Vesiurheilutukku Oy | Wholesale & retail | 1997 |
| Suomen Vuokrakopit Oy | Administrative & support | 1984 |
| Suomen kirkonkellohuolto Oy | Construction | 2024 |
| Suomipähkinä Oy | Wholesale & retail | 2025 |
| Super Heat Oy | Construction | 2022 |
| Supersepät Oy | Other services | 1978 |
| Suu ja Säde Oy | Health & social care | 2017 |
| Suunnittelutoimisto Hotanen Oy | Professional & scientific | 2011 |
| Sähkö Vihreä Oy | Construction | 2020 |
| Sähkö- ja nosturipaja SNP Oy | Construction | 2019 |
| Sähkö-Aalto Oy | Construction | 2000 |
| Sähkö-Linkku Oy | Construction | 2025 |
| Sähkö-Savolainen Oy | Construction | 2019 |
| SähköGrid Oy | Construction | 2020 |
| Sähköasennus Raitakari Oy | Construction | 2017 |
| Sähköpalvelu Jokinen Oy | Construction | 2024 |
| Sähkötyö Kössi Ky | Construction | 1998 |
| Sählysirkus Oy | Professional & scientific | 1994 |
| Säkylän Tarvikepalvelu Oy | Wholesale & retail | 2017 |
| Särmä Raisio Oy | Construction | 2020 |
| T & T Marks Oy | Professional & scientific | 1996 |
| TA Engineering Oy | Construction | 2026 |
| Teamer OY | Education | 2020 |
| Teollisuus Eristys Sorri OY | Construction | 2008 |
| TERAMA Oy | Construction | 2004 |
| TIKA Group Oy | Construction | 2015 |
| TJ Electric Project Oy | Manufacturing | 2025 |
| TJL-Marine Oy | Construction | 2017 |
| TK Talous Oy | Wholesale & retail | 1993 |
| TK-Rakenne Oy | Construction | 2023 |
| TKY Rakennus Oy | Administrative & support | 2018 |
| TL-Motors Oy | Other services | 2021 |
| TM Tapahtumamatkat Oy | Administrative & support | 2012 |
| TOP Kiinteistöhuolto Oy | Administrative & support | 2022 |
| TP-Talli Avoin yhtiö | Arts & recreation | 2008 |
| TPR Consulting Oy | Financial services | 2026 |
| TQ-Auto Oy | Other services | 2004 |
| TRP Group Oy | Construction | 2023 |
| TRS Finn OY | Professional & scientific | 2012 |
| TT-Advisor Oy | Other services | 1989 |
| TTH-Turun Teollisuushuolto Oy | Administrative & support | 2010 |
| TTK-Rakennus & Nosturipalvelu Oy | Construction | 2025 |
| TUK-Markkinointi Oy | Financial services | 1994 |
| Tahtitiimi Oy | Construction | 2023 |
| Taideosuuskunta Kruunu | Arts & recreation | 2020 |
| Taikamo osk. | Transport & logistics | 2013 |
| Taitoset Oy | Arts & recreation | 2013 |
| Taksi 95 - Välilä Oy | Transport & logistics | 1998 |
| Taksi K. Salminen Oy | Transport & logistics | 2013 |
| Taksi Sanna Hurme Oy | Transport & logistics | 2018 |
| Taksi Satu Oksanen Oy | Transport & logistics | 2019 |
| Taksiaseman Taksit Oy Turku | Transport & logistics | 1994 |
| Taksiliikenne K&B oy | Transport & logistics | 2020 |
| Talotekniikka Forsblom Oy | Construction | 2005 |
| Talousninja Oy | Professional & scientific | 2020 |
| Tankkipojat Oy | Administrative & support | 1991 |
| Tarw-Trading Oy Ltd | Wholesale & retail | 2008 |
| Tasalan Huolto Oy | Administrative & support | 1979 |
| Tasetiimi Oy | Professional & scientific | 1991 |
| Tasi Group Oy | Wholesale & retail | 2025 |
| Tasoa Oy | Professional & scientific | 2018 |
| Taxi Teijo Järvi Oy | Transport & logistics | 2014 |
| TecDec Marketing Oy | Wholesale & retail | 2006 |
| Tech Electric Turku Oy | Construction | 2015 |
| Tech Enthusiast Oy | Information & communication | 2013 |
| Teemu LD Oy | Arts & recreation | 2022 |