| Stankowski Oy | Professional & scientific | 2026 |
| Star Icon Oy | Administrative & support | 2026 |
| Starfinance Oy | Financial services | 2016 |
| Starflight Entertainment Oy | Information & communication | 2017 |
| Steamore Oy | Education | 2020 |
| Stebb Invest Oy | Real estate | 2025 |
| Steel Capital Oy | Manufacturing | 2008 |
| Steel Group Pohjanmaa Oy | Manufacturing | 2021 |
| Steelpond Oy | Wholesale & retail | 1991 |
| Stelon Oy | Manufacturing | 2012 |
| StenPec Oy | Construction | 2022 |
| Stenberg Hellsten Oy | Wholesale & retail | 2015 |
| Stenberg Living Oy | Real estate | 2024 |
| Stenfors Tekniikka Oy | Construction | 1995 |
| Stenger & Ibsen Construction Finland Oy | Construction | 2022 |
| Steppenwolf Oy | Professional & scientific | 1989 |
| Stidi Solutions Oy | Information & communication | 2025 |
| Stijnspul Oy | Financial services | 2019 |
| Still Ventures Oy | Financial services | 2017 |
| Stiocon Oy | Real estate | 1998 |
| Stoka Oy | Wholesale & retail | 2008 |
| Stolen Organ Oy | Arts & recreation | 2020 |
| Stoneheed Oy | Manufacturing | 2026 |
| Stormbit Oy | Information & communication | 2010 |
| Stride Print avoin yhtiö | Manufacturing | 2025 |
| Strive Higher Oy | Financial services | 2019 |
| Studio ART Oy | Professional & scientific | 2006 |
| Studio Goldsmith Oy | Information & communication | 2019 |
| Studio Ilpo Okkonen Oy | Professional & scientific | 1994 |
| Studio Kubik Oy | Professional & scientific | 2017 |
| Studio Muste Oy | Education | 2023 |
| Studio Outo Oy | Information & communication | 2003 |
| Studio Theodor Oy | Professional & scientific | 2025 |
| Studio Timo Heikkala Oy | Professional & scientific | 2004 |
| Studio Uleåborg Oy | Other services | 2012 |
| Studio44 Oy | Other services | 2007 |
| SubConstruction Oy | Professional & scientific | 2012 |
| Sulon Lemmikkituhkaus Oy | Other services | 2019 |
| Sultans of Swing Oy | Wholesale & retail | 2022 |
| Sumaksion Oy | Financial services | 2022 |
| Summa Finland Oy | Other services | 2021 |
| Summit Holding Oy | Financial services | 2025 |
| Sun 1 Oy | Agriculture & fishing | 2021 |
| Sun 3 Oy | Agriculture & fishing | 2022 |
| Sun Tammela Oy | Agriculture & fishing | 2022 |
| SunGyne Oy | Health & social care | 2014 |
| Sundquist & Karvonen Oy | Health & social care | 2023 |
| Sunicon Oy | Manufacturing | 2013 |
| Sunila Consulting Oy | Professional & scientific | 2019 |
| Sunion Tech Oy | Administrative & support | 2026 |
| Sunpanels Oy | Wholesale & retail | 2023 |
| Sunshine Early Learning Centre Oy | Education | 2014 |
| Sunstone Yield Oy | Financial services | 2025 |
| Sun Sata Oy | Agriculture & fishing | 2022 |
| Suo Commerce Oy | Information & communication | 2025 |
| Suojapinnoitus Finland Oy | Construction | 2019 |
| Suolamänty Oy | Real estate | 2007 |
| Suomen 16100 Oy | Professional & scientific | 2008 |
| Suomen Akkutalo Oy | Wholesale & retail | 2024 |
| Suomen Asuntoactiva LKV Oy | Real estate | 2003 |
| Suomen Autohuolto Oy | Other services | 2011 |
| Suomen Bioanalytiikka Oy | Professional & scientific | 1996 |
| Suomen CBA Trading Oy | Construction | 1990 |
| Suomen Contfix Oy | Manufacturing | 2012 |
| Suomen Debit Oy | Professional & scientific | 1990 |
| Suomen Elektroniikkatukku Ky | Wholesale & retail | 1992 |
| Suomen Erikoisrahoitus Oy Finnish Special Finance Ltd | Financial services | 1982 |
| Suomen Erikoistukku Oy | Wholesale & retail | 2013 |
| Suomen Erikoisvaruste Oy | Wholesale & retail | 2006 |
| Suomen Eristystekniikka Oy | Construction | 2016 |
| Suomen Hoito- ja Hoivatyö Oy | Health & social care | 2009 |
| Suomen Huopakatto Oy | Construction | 2014 |
| Suomen Hyvinvointitilat Oy | Real estate | 2023 |
| Suomen Hyvän Kaupan Paikka Oy | Wholesale & retail | 2006 |
| Suomen Ilmatar Oy | Wholesale & retail | 2014 |
| Suomen Juristit Oy | Professional & scientific | 2008 |
| Suomen Keittiöteollisuus KY | Wholesale & retail | 2004 |
| Suomen Keskusasunnot Oy | Real estate | 2016 |
| Suomen Kiinteistöhallinta Oy | Professional & scientific | 2017 |
| Suomen Konesiirrot Oy | Transport & logistics | 2018 |
| Suomen Konevuokraamo Oy | Administrative & support | 2019 |
| Suomen Koodikoulu Oy | Education | 2017 |
| Suomen Kotikiva Oy | Real estate | 2022 |
| Suomen Koulukiinteistöt Oy | Real estate | 2022 |
| Suomen Kuitutekniikka Oy | Construction | 2015 |
| Suomen Kulkine Oy | Wholesale & retail | 2022 |
| Suomen Kuntakiinteistöt Oy | Real estate | 2022 |
| Suomen Kuntokeskukset Oy | Other services | 2024 |
| Suomen Kuntolat Oy | Health & social care | 2016 |
| Suomen Kuulotuki Oy | Health & social care | 2018 |
| Suomen Laatuisännöinti Oy | Real estate | 2021 |
| Suomen Lainakontti Oy | Administrative & support | 2005 |
| Suomen Lasermaalaus Oy | Construction | 2021 |
| Suomen Lähijätski Oy | Wholesale & retail | 2014 |
| Suomen Mallikuvat Oy | Professional & scientific | 2008 |
| Suomen Mittaritukku Oy | Wholesale & retail | 2019 |
| Suomen Musiikkikoulut Oy | Wholesale & retail | 2007 |
| Suomen Paikallinen Mainostoimisto -verkosto Oy | Professional & scientific | 2005 |
| Suomen Paikallislehtipalvelu Oy | Information & communication | 1983 |
| Suomen Pest Torjunta Oy | Administrative & support | 2023 |