| S Toivanen Oy | Arts & recreation | 1997 |
| Seplan Atk-Palvelu Ky | Information & communication | 2002 |
| SET-Systems Oy | Wholesale & retail | 2002 |
| SH-Lines OY | Transport & logistics | 2020 |
| SM Power-Line Service Oy | Administrative & support | 2015 |
| SM-Valoset Oy | Professional & scientific | 2019 |
| SPX FLOW Finland Holdings Oy | Financial services | 1983 |
| Saaristokeskus Seksmiilari Oy | Wholesale & retail | 1999 |
| Sakari Vintage Oy | Wholesale & retail | 2023 |
| Salmen Kartanon Palvelukeskus Oy | Health & social care | 1994 |
| Salmerin Kiinteistöt Oy | Real estate | 1989 |
| Samdrill Oy | Construction | 2024 |
| Sami Häätylä Oy | Professional & scientific | 2016 |
| Sami Jäspilä Oy | Real estate | 2008 |
| Saneerausrakentajat Nummela Oy | Construction | 1998 |
| Sannin paperi & kirja Oy | Wholesale & retail | 2024 |
| Santtion Kebab Pizzeria Oy | Hospitality | 2024 |
| Santtion Siivous Oy | Administrative & support | 2011 |
| Sapodilla Oy | Real estate | 2016 |
| Sasto Oy | Wholesale & retail | 2022 |
| Saviranta Oy | Real estate | 1993 |
| Se-Wik Oy | Real estate | 2004 |
| Seger Oy | Manufacturing | 1992 |
| Sektoriloisto oy | Hospitality | 2014 |
| Selectric Oy | Construction | 2018 |
| Selkämeren Jää Oy | Manufacturing | 1982 |
| Sepänkadun Ryhmis Oy | Health & social care | 2011 |
| Seveca Oy | Health & social care | 2018 |
| ShengJing Oy | Hospitality | 2023 |
| Signaalimaailma ky | Wholesale & retail | 1994 |
| Siivosen Hautaustoimisto ja Kukkapirtti Oy | Wholesale & retail | 1977 |
| Siivouspalvelu Sippo Konttinen Ky | Administrative & support | 1989 |
| Simmons Food & Beverage Ky | Hospitality | 2014 |
| Simmons Foods Oy | Manufacturing | 2017 |
| Simplef Oy | Professional & scientific | 2017 |
| Simtekon Oy | Professional & scientific | 1987 |
| Sisustus Ulpukka Oy | Wholesale & retail | 2021 |
| Sitadelli Oy | Administrative & support | 2021 |
| Six Miles Oy | Professional & scientific | 2019 |
| Sjöberg & Wallenius Oy | Manufacturing | 2017 |
| Soifa Oy | Hospitality | 2018 |
| Southwest Service Oy | Manufacturing | 2020 |
| SportMasago Oy | Health & social care | 2019 |
| Steel Helminen Oy | Manufacturing | 2024 |
| Summa Ports Oy | Agriculture & fishing | 1998 |
| Sundholmantien viemäriosuuskunta | Water & waste | 2012 |
| Suomen Katkarapu Oy | Agriculture & fishing | 2016 |
| Suomen Kotiapu Oy | Health & social care | 2020 |
| Suomen Laserpalvelu Oy | Professional & scientific | 2008 |
| Sustaki Solutions Oy | Information & communication | 2021 |
| Suukarin Vene Oy | Manufacturing | 2016 |
| Suutari ja Avainpaja Väärti Oy | Other services | 2010 |
| Sähköpalvelu JT-Mesta Oy | Construction | 2022 |
| Sähkötyö Nextel oy | Construction | 2025 |
| Sähkötyöt P. Koskelin Oy | Construction | 2015 |
| Säästöpankki Kalanti-Pyhäranta | Financial services | 1919 |
| T & H Laaksonen Oy | Transport & logistics | 2013 |
| T & T takuutyö oy | Administrative & support | 2013 |
| TAITOVAKKA Työosuuskunta | Administrative & support | 1995 |
| TATE Group Oy | Real estate | 2025 |
| TKP Talvinen Oy | Administrative & support | 2008 |
| TLJS - Invest Oy | Financial services | 2021 |
| TR Cyber Consulting Oy | Professional & scientific | 2025 |
| TT-Paja Oy | Construction | 1995 |
| Taksi Saarenpää Oy | Transport & logistics | 2019 |
| Talotekniikka Uotila Ky | Professional & scientific | 1995 |
| Taloushallinto J.Suominen Oy | Professional & scientific | 2018 |
| Tanssikoulu Tanssin Sydän Ky | Education | 2016 |
| Tapiotalo Oy | Construction | 2022 |
| Tedesco Oy | Professional & scientific | 1990 |
| Telesilta Oy | Construction | 2003 |
| Telmarin Oy | Wholesale & retail | 1997 |
| Tili- ja Kiinteistö Avuxi Oy | Real estate | 2014 |
| Tilisaari Oy | Professional & scientific | 2016 |
| Tilitoimisto Liisa Aaltonen Ky | Professional & scientific | 1989 |
| Tilitoimisto PPJ Oy | Professional & scientific | 2020 |
| Timanttiporaus ja -sahaus T. Sourulahti Oy | Manufacturing | 2025 |
| To Johnny Oy | Manufacturing | 2025 |
| ToKiv Group Oy | Financial services | 2026 |
| ToKiv Oy | Construction | 2025 |
| Toivo-sijoitus Oy | Financial services | 1986 |
| Torikioski Tero Lindström Ky | Wholesale & retail | 1987 |
| Totaalipurku Oy | Construction | 2013 |
| Total Gym Oy | Arts & recreation | 2008 |
| Troolari Olympos Oy | Agriculture & fishing | 2017 |
| Tsägä Holding Oy | Financial services | 2021 |
| Tukewa palvelut oy | Administrative & support | 2020 |
| Tuulenhauki Oy | Administrative & support | 2009 |
| Tännäi Oy | Transport & logistics | 2026 |
| U-Gis Mittaus Oy | Professional & scientific | 2025 |
| U. Luotonen ja Kumpp. Työkaluvalmistamo | Manufacturing | 1973 |
| U:gin Asunto Auto Vuokraus Oy | Other services | 2019 |
| U:gin Import Ky | Wholesale & retail | 1990 |
| U:gin Maalaustyöt Oy | Construction | 2006 |
| U:gin Marenki Oy | Wholesale & retail | 2007 |
| U:gin Mattotyöt Oy | Construction | 2015 |
| U:gin Nostokori Oy | Construction | 1997 |
| U:gin Sähköpiste Oy | Construction | 1990 |
| U:gin Taksiasema Oy | Transport & logistics | 2001 |
| Ubio Oy | Wholesale & retail | 2011 |