| Sulo Anttisaari Oy | Construction | 1971 |
| Suoluhta Oy | Administrative & support | 2023 |
| Suomen Arvotavaravälitys Oy | Wholesale & retail | 1997 |
| Suomen Asuntotukku Oy | Real estate | 2020 |
| Suomen Helakeskus Oy | Wholesale & retail | 1978 |
| Suomen Hypnoosi- ja Psykovalmennus Keskus Oy | Health & social care | 1987 |
| Suomen Luontovarma Oy | Agriculture & fishing | 2021 |
| Suomen Mallinnusmittaus Oy | Professional & scientific | 1998 |
| Suomen Prosessikemia Oy | Wholesale & retail | 2012 |
| Suomen Putkitukku Oy | Wholesale & retail | 2007 |
| Suomen Rakennus & Viherpalvelu SRVP Oy | Construction | 1998 |
| Suomen Rengasverkkokauppa Oy | Wholesale & retail | 2025 |
| Suomen Sähkö-Data Oy | Professional & scientific | 1988 |
| Suomen Taidetarvike Ky | Wholesale & retail | 1982 |
| Suomen Tilasäiliö Oy | Wholesale & retail | 2017 |
| Suomen Työkone Oy | Wholesale & retail | 2015 |
| Suomen Työkone Service Oy | Other services | 2024 |
| Suomen Yrityskaupat Pohjanmaa Oy | Professional & scientific | 2015 |
| Suomenselän Marketing Ky | Wholesale & retail | 1982 |
| Suomi-Yhtiö Oy | Professional & scientific | 2024 |
| Super Mainio Oy | Wholesale & retail | 1987 |
| SuunAsia Oy | Health & social care | 2026 |
| Suunnittelu Roos Oy | Professional & scientific | 2014 |
| Suupohjan Kaluste Ky | Manufacturing | 1979 |
| Suurusrehu Oy | Real estate | 1989 |
| Suutkanen Oy | Real estate | 2017 |
| Suvi Solutions Oy | Financial services | 2024 |
| Suvifood oy | Hospitality | 2019 |
| Sydänmaa-Invest Oy | Real estate | 2009 |
| Syrjälän kotileipomo Oy | Hospitality | 2022 |
| Syspoint Oy | Information & communication | 1998 |
| System Lahti Oy | Wholesale & retail | 1993 |
| Syty Consulting Oy | Professional & scientific | 2025 |
| Sähkö Lakeus Oy | Construction | 2006 |
| SähköSein Ky | Construction | 2006 |
| Sähköasennus Elegance Oy | Construction | 2026 |
| Sähköasennus Kohtamäki Oy | Construction | 1989 |
| Sähkötyö Hietanen Oy | Construction | 2025 |
| T&J Automaalaus ja kolarikorjaus Avoin yhtiö | Other services | 2003 |
| T&M-Myynti Seinäjoki Oy | Wholesale & retail | 2016 |
| T-Market Hintatori Ky | Wholesale & retail | 1988 |
| T-Market Viitala Ky | Wholesale & retail | 1981 |
| T. Tuuma Oy | Construction | 2008 |
| T.Luopajärvi Ky | Transport & logistics | 2007 |
| T.SORTTIMENTTI Oy | Wholesale & retail | 2018 |
| T3J Sijoitus Oy | Real estate | 2019 |
| TA Dental Oy | Health & social care | 2022 |
| TANInternational Oy | Wholesale & retail | 2019 |
| TARU Interior Oy | Professional & scientific | 2020 |
| TAVCons Oy | Professional & scientific | 2016 |
| Tela-Asunnot OY | Real estate | 2020 |
| TF Holding Oy | Financial services | 2021 |
| TI Rakennus Oy | Construction | 2021 |
| TJ Tapahtumajärjestäjät Oy | Arts & recreation | 2017 |
| TJW Consulting Oy | Professional & scientific | 2023 |
| TKV Yhtiöt Oy | Real estate | 2020 |
| TLS Way Oy | Transport & logistics | 2024 |
| Tmh-Ratkaisu OY | Manufacturing | 2020 |
| TMK Holding Oy | Financial services | 2022 |
| TMT-Talotekniikka Oy | Construction | 2017 |
| TN Ultraäänipalvelut Oy | Health & social care | 2010 |
| TNC-Nordic Oy | Wholesale & retail | 1997 |
| TO Engineering Oy | Professional & scientific | 2021 |
| Tonitek OY | Wholesale & retail | 2024 |
| Topmedical OY | Health & social care | 2007 |
| TP Indusol Oy | Professional & scientific | 2023 |
| TPE-Works Oy | Professional & scientific | 2024 |
| TR Insurance Oy | Financial services | 2024 |
| TRV-Networks Oy | Information & communication | 2001 |
| TS Medi Oy | Health & social care | 2020 |
| TS-Laboratories Oy | Health & social care | 2022 |
| TSS Consulting Oy | Financial services | 2020 |
| TTL Invest Oy | Financial services | 2020 |
| TTM Audit Oy | Administrative & support | 2016 |
| TacAL Ky | Manufacturing | 2012 |
| Tacomo Oy | Administrative & support | 2004 |
| Tahtoverstas Ky | Education | 1978 |
| Taica Invest Oy | Real estate | 2022 |
| Taidolla ja Tuurilla Oy | Real estate | 2020 |
| Taitovaara Oy | Professional & scientific | 2004 |
| Taivastuuli Oy | Real estate | 2024 |
| Taju Setup Oy | Construction | 2021 |
| Takala Sales Oy | Financial services | 2021 |
| Takalan Asianajotoimisto Jukka Leppänen Oy | Professional & scientific | 1983 |
| Takalan Konepaja Oy | Manufacturing | 2018 |
| Takku ja Rakit Oy | Agriculture & fishing | 2024 |
| Taksi Palo Ky | Transport & logistics | 2016 |
| Taksi-Mäkynen Oy | Transport & logistics | 2007 |
| TaksiON Oy | Transport & logistics | 2017 |
| Taksipalvelu Kujansuu Oy | Transport & logistics | 2020 |
| Talleroinen Oy | Hospitality | 2019 |
| Talli Länsimäki Ky | Arts & recreation | 1995 |
| Talli Oman Onnen Sepät Oy | Real estate | 2021 |
| Talonhenki Etelä-Pohjanmaa Oy | Administrative & support | 2019 |
| Talotekniikka Koivuluoma Oy | Construction | 2011 |
| Talousystävä Oy | Professional & scientific | 2024 |
| Tamim Oy | Hospitality | 2022 |
| Tampereen Reunahiomo Ky | Manufacturing | 2003 |
| Tanja Korpela Oy | Professional & scientific | 2023 |
| Tank Pro Oy | Manufacturing | 2014 |