| Silvenna Holding Oy | Financial services | 2026 |
| Silver Auto Invest Oy | Other services | 2021 |
| Simontointi Oy | Construction | 2021 |
| Sinna Group Oy | Other services | 2020 |
| Sinun Kotihoito Oy | Health & social care | 2020 |
| Sisko Creative Oy | Professional & scientific | 2018 |
| SkifLog Ky | Education | 2009 |
| Smart Map Oy | Information & communication | 2021 |
| Sorby Oy | Manufacturing | 1983 |
| Sotkian Valimo Oy | Manufacturing | 1998 |
| Sotkian-Kurisjärven vesiosuuskunta | Water & waste | 2005 |
| Souper Oy | Hospitality | 2008 |
| Speedweekend Oy | Other services | 2022 |
| SportsMill Finland Oy | Education | 2023 |
| Steel Vision Oy | Manufacturing | 2000 |
| Steely Design Kimmo&Mira Oy | Manufacturing | 2021 |
| Strongbase Oy | Other services | 2018 |
| Sulo Yhtiöt Oy | Wholesale & retail | 2022 |
| Suomen Elektroterapia Oy | Wholesale & retail | 1997 |
| Suomen Linjaraivaus Oy | Construction | 2010 |
| Suomen puhtaanapito- ja kiinteistöpalvelu Oy | Administrative & support | 2020 |
| Suoraputki Oy | Construction | 2020 |
| Sähkö Tesla Oy | Construction | 2011 |
| Sähkö-Elina Oy | Professional & scientific | 2010 |
| SähköSäätö Oy | Construction | 2024 |
| Sähköpiiri Oy | Construction | 1989 |
| Tamsec Finland OY | Administrative & support | 2010 |
| Tarmotapiot OY | Administrative & support | 2011 |
| TDM Works Oy | Manufacturing | 2026 |
| TDM-Engineering Oy | Professional & scientific | 1990 |
| Tilikuva OY | Professional & scientific | 2021 |
| TJ-Ratkaisut Oy | Administrative & support | 2012 |
| TJH-Service OY | Manufacturing | 2015 |
| TK Hallintopalvelut Karvinen Oy | Professional & scientific | 2018 |
| TKM TTT Finland Oy | Manufacturing | 1995 |
| TL Autopesu Oy | Other services | 2016 |
| TM-Group Oy | Administrative & support | 2020 |
| TMI Yhtiöt Oy | Professional & scientific | 2021 |
| TNT Akaa OY | Transport & logistics | 2022 |
| TP Jantunen Oy | Transport & logistics | 1998 |
| TSA-Tekniikka Oy | Construction | 2025 |
| TUPLA-J Rakennus Oy | Construction | 2023 |
| Taideviita Oy | Professional & scientific | 1983 |
| Talouscare Oy | Professional & scientific | 2020 |
| TamGrass Oy | Administrative & support | 2025 |
| Tamec Ky | Manufacturing | 1987 |
| Tamspark Oy | Wholesale & retail | 2007 |
| Tannerma Consulting Oy | Information & communication | 2026 |
| Target Sales Oy | Wholesale & retail | 2019 |
| Tasqu Oy | Information & communication | 2025 |
| Tataska Ky | Information & communication | 2005 |
| Team MBO Oy | Professional & scientific | 2022 |
| Teatteri Pikkuplaneetta Oy | Arts & recreation | 2011 |
| Teemu Karppinen Oy | Arts & recreation | 2022 |
| Teknopolku Oy | Professional & scientific | 2006 |
| Tekstiilipalvelu Oy | Wholesale & retail | 1986 |
| Terinen Oy | Agriculture & fishing | 2007 |
| Terissaari Oy | Manufacturing | 1987 |
| Teräs ja Autopelti Kankkunen Ky | Other services | 1986 |
| Teräsneliö Oy | Wholesale & retail | 2010 |
| The GoodMess Oy | Professional & scientific | 2024 |
| Tili ja tarkastus Olli Lehtimäki Oy | Professional & scientific | 1994 |
| Tillin Talli Oy | Financial services | 2025 |
| Timo Hakala Oy | Manufacturing | 2021 |
| Timo Saarinen Oy | Professional & scientific | 2006 |
| Timor Rakennus Oy | Construction | 2023 |
| Toijala Works Oy | Manufacturing | 2000 |
| Toijalan Elemec Oy | Manufacturing | 1990 |
| Toijalan Hionta ja Lasermittaus Oy | Manufacturing | 1993 |
| Toijalan Kiinteistöhuolto Oy | Administrative & support | 1986 |
| Toijalan Kiinteistönvälitys Oy | Real estate | 1992 |
| Toijalan Kiviveistämö Oy | Manufacturing | 1985 |
| Toijalan Kone ja Kuljetus Ky | Transport & logistics | 1985 |
| Toijalan Koneterä Oy | Manufacturing | 1987 |
| Toijalan Konetuote Oy | Manufacturing | 1991 |
| Toijalan LVI-Palvelu Oy | Construction | 2013 |
| Toijalan Muuntamo Oy | Real estate | 2003 |
| Toijalan Rakennustarvike Oy | Wholesale & retail | 2004 |
| Toijalan Raskaskone Oy | Other services | 1986 |
| Toijalan Taltta Oy | Real estate | 1995 |
| Toijalan Taplee Oy | Hospitality | 1989 |
| Toijalan Tilitoimisto Oy | Professional & scientific | 1972 |
| Toijalan Värikauppa Oy | Wholesale & retail | 1986 |
| Toijalan Yrityspalvelu Oy | Professional & scientific | 1993 |
| Toijalan ja Vesilahden Kuntokeskus Ky | Health & social care | 1982 |
| Toika Oy | Manufacturing | 2020 |
| Toivemeri Oy | Other services | 2021 |
| Toivosto Oy | Professional & scientific | 2023 |
| Tolkku SEO Oy | Information & communication | 2026 |
| Tolvilan Kartano Oy | Real estate | 2010 |
| Torkon alueen huolto-osakeyhtiö | Energy | 1978 |
| Toserak Oy | Construction | 1977 |
| Transparent Eyeball Oy | Professional & scientific | 2015 |
| Tredunet Oy | Information & communication | 1998 |
| Träskman Yhtiöt Oy | Other services | 2019 |
| Tsek Rakennus Oy | Construction | 2019 |
| Tuomo Halonen Oy | Manufacturing | 1997 |
| TuoteLinja Oy | Wholesale & retail | 2026 |
| Turren Kaivin oy | Construction | 2024 |
| Työhuone Tuulensuu Oy | Wholesale & retail | 1990 |