| Suomen Vartiomiehet Oy | Administrative & support | 2009 |
| Susako Oy | Other services | 2019 |
| Suunnittelupalvelu Lempola Avoin yhtiö | Professional & scientific | 1996 |
| Suunnittelutoimisto Välitalo Oy | Professional & scientific | 2021 |
| Sweet Femi Oy | Other services | 2020 |
| Syvyys Oy | Arts & recreation | 2019 |
| Sähkö-Kirsilät | Construction | 2004 |
| Sähköinsinööritoimisto Ratex Oy | Professional & scientific | 2003 |
| Sähkökit Oy | Construction | 2023 |
| Sähköteko Oy | Construction | 2013 |
| Säiliö Ykköset Oy | Professional & scientific | 2006 |
| Särmä Communications Oy | Professional & scientific | 2016 |
| Sävelsaari Avoin yhtiö | Arts & recreation | 2022 |
| T & N Laatutaksi Oy | Transport & logistics | 2018 |
| T&J Syri avoin yhtiö | Administrative & support | 1995 |
| T&J-autocenter Ky | Wholesale & retail | 2021 |
| T&L Cranes Oy | Manufacturing | 2023 |
| T. Salonen Oy | Professional & scientific | 1996 |
| T. Tattari Oy | Real estate | 1990 |
| T. Wacklin Oy | Transport & logistics | 2020 |
| T.Ylikorpi Oy | Arts & recreation | 2009 |
| Taksipalvelut Yli-Hallila OY | Transport & logistics | 2018 |
| TAMASO Oy | Administrative & support | 2014 |
| TE Export Oy | Manufacturing | 2007 |
| TEAM Syri avoin yhtiö | Wholesale & retail | 2002 |
| TEKA Capital Oy | Financial services | 2020 |
| Tepako OY | Manufacturing | 2008 |
| TERENDO Oy | Wholesale & retail | 2018 |
| TETRA Chemicals Europe Oy | Manufacturing | 2004 |
| TF Service Oy | Other services | 2020 |
| TH - Quality Oy | Construction | 2026 |
| TH Safety Oy | Administrative & support | 2025 |
| TH Trade Oy | Other services | 2015 |
| TI-Pinta Oy Ab | Professional & scientific | 1996 |
| TJ-Kiinteistöt Oy | Hospitality | 2022 |
| TK-Yritysvalmennus Oy Ab | Professional & scientific | 1990 |
| TM Purku Oy | Construction | 2022 |
| TP-Housing Oy | Real estate | 2005 |
| TPM Group Oy | Construction | 2021 |
| TT-Röntgen Oy | Health & social care | 2016 |
| Tabw Oy | Information & communication | 2019 |
| Taimitaikurit Oy | Agriculture & fishing | 1990 |
| Taksi Koutonen & Läspä Oy | Transport & logistics | 2025 |
| Taksipalvelu Jaakko Oy | Transport & logistics | 2022 |
| Taksipalvelu Turpeinen Oy | Transport & logistics | 2010 |
| Taksipalvelut Sandkvist Oy | Transport & logistics | 2022 |
| Talent Invest Oy | Real estate | 2018 |
| Talohuolto Aro Oy | Administrative & support | 2012 |
| TalousTaito Piispanen Oy | Professional & scientific | 2024 |
| Talousparoni Oy | Administrative & support | 2023 |
| Tandläkare Tom Nygård Ab | Health & social care | 2013 |
| Tankarin Saaripalvelut avoin yhtiö | Hospitality | 2016 |
| Tapsamtuote avoin yhtiö | Construction | 1994 |
| Tapsan Haalarit Oy | Manufacturing | 2017 |
| Taram Oy | Real estate | 2026 |
| Tarvehuolto oy | Construction | 2024 |
| Tasoite- ja maalauspalvelu Niemi & Sandkvist Oy | Construction | 2017 |
| Tauno Harju Oy | Construction | 1995 |
| Taxi ja Kuljetus Keski-Pohjanmaa Oy | Transport & logistics | 2018 |
| TeRiJaKi Capital Oy | Financial services | 2024 |
| Team Backlund Ky | Wholesale & retail | 2009 |
| Team Kaartamo Oy | Construction | 2007 |
| Team WSB Rakennus Oy Byggnads Ab | Construction | 2023 |
| Teamprint Holding Oy | Real estate | 2021 |
| Teamprint Oy | Manufacturing | 2017 |
| TechService H.Ö Oy Ab | Information & communication | 2022 |
| Teemu Herlevi Oy | Financial services | 2005 |
| Teemu Peltola Oy | Construction | 2015 |
| Tegridy Farms Oy | Real estate | 2022 |
| Teknologiayritys Smart & Cool Oy | Professional & scientific | 1997 |
| Tekos Oy | Transport & logistics | 2020 |
| Tekplast Oy | Wholesale & retail | 2013 |
| Tekplast holding Oy | Financial services | 2024 |
| Telvi OY | Construction | 2018 |
| Tender Finland Oy | Administrative & support | 2020 |
| Tennis- ja padelvalmennus Salonen Oy | Education | 2025 |
| Teollisuus Palje Oy | Manufacturing | 2019 |
| Terassiykköset Oy | Financial services | 2019 |
| Terminaali Invest Oy | Financial services | 2022 |
| Terminaalikadun Tekniikka Oy | Construction | 2020 |
| Terminus zibda Oy | Professional & scientific | 2022 |
| Tervahovin Rohto Oy | Wholesale & retail | 2022 |
| Teräspalvelu Matikainen Oy | Manufacturing | 2004 |
| Texmiss Oy | Wholesale & retail | 1995 |
| Thodén Oy Ab | Real estate | 2023 |
| TiTo Boats Oy | Manufacturing | 2013 |
| Tieva Lakitoimisto Oy | Professional & scientific | 2025 |
| Tigon Oy Ltd | Arts & recreation | 2008 |
| Tiiti Service Oy | Hospitality | 2002 |
| Tili- & Konsulttitoimisto Ky Salex Kb | Professional & scientific | 1990 |
| Tilintarkastus Kasikos Oy | Administrative & support | 2022 |
| Tilintarkastus Kivi Oy | Professional & scientific | 2012 |
| Tilintarkastus Peltomaa Oy | Professional & scientific | 2022 |
| Tilintarkastus Sjöberg Oy | Professional & scientific | 2021 |
| Tilitoimisto Attasea Ky | Professional & scientific | 1995 |
| Tilitoimisto Eino Honkaniemi Ky | Professional & scientific | 1985 |
| Tilitoimisto Kajapa Oy | Professional & scientific | 2017 |
| Tilitoimisto Linkki Oy | Professional & scientific | 2004 |
| Tilitoimisto Pulkkinen Oy | Professional & scientific | 2010 |
| Tilitoimisto R. Mannström Oy | Professional & scientific | 2019 |