| Ti-Pi Laukku Oy | Wholesale & retail | 2014 |
| Tian Zhou Oy | Hospitality | 2022 |
| Tieto-Velju Oy | Professional & scientific | 2009 |
| Tietokonekellari Oy | Wholesale & retail | 2010 |
| Tietomeri Oy | Information & communication | 1985 |
| Tietotek Oy | Information & communication | 2024 |
| Tiijoki Oy | Financial services | 2024 |
| Tiilimäen Romuliike Oy | Wholesale & retail | 1958 |
| Tiiliruukin Sijoitus Oy | Financial services | 2024 |
| Tiina Elina Toivonen Consulting Kommandiittiyhtiö | Professional & scientific | 1989 |
| Tikka Asunnot Oy | Real estate | 2014 |
| Tikka Racing Oy | Manufacturing | 2007 |
| Tilenius Oy | Real estate | 2019 |
| Tili- ja Yrityspalvelu A. Jantunen Ky | Professional & scientific | 2004 |
| Tiliasema Minna Seessalo Oy | Professional & scientific | 2021 |
| Tilikuukkari Oy | Professional & scientific | 1991 |
| Tilinota Oy | Real estate | 1992 |
| Tilinovo Ky | Professional & scientific | 1991 |
| Tilinpitotiimi Oy | Professional & scientific | 2009 |
| Tilintarkastus Paananen Oy | Administrative & support | 1995 |
| Tilintarkastus Puputti Oy | Financial services | 2013 |
| Tilintarkastus ja Yrityskonsultointi Markku Leino Oy | Professional & scientific | 1989 |
| Tilipalvelu Marita Ojala Oy | Professional & scientific | 1981 |
| Tilipalvelu NoTe Oy | Professional & scientific | 2017 |
| Tilipartners Oy | Professional & scientific | 2017 |
| Tilitoimisto Arelina Oy | Professional & scientific | 2025 |
| Tilitoimisto Huhdanmäki Oy | Professional & scientific | 1989 |
| Tilitoimisto Jantunen Oy | Professional & scientific | 2010 |
| Tilitoimisto Kaarto Oy | Professional & scientific | 2025 |
| Tilitoimisto Nevalainen Oy | Professional & scientific | 1991 |
| Tilitoimisto Rosendahl Oy | Professional & scientific | 2017 |
| Tilitoimisto TimoTak Oy | Professional & scientific | 2018 |
| Tilivaaka Ky | Professional & scientific | 1993 |
| Timanttityö Ratila Oy | Construction | 2024 |
| Timanttityöt P. Nieminen Oy | Construction | 2011 |
| Timberfinder Oy | Professional & scientific | 2017 |
| Timeless Group Oy | Wholesale & retail | 2020 |
| Timmeri Oy | Manufacturing | 2008 |
| Timo Villman Oy | Transport & logistics | 1986 |
| Timoteos Oy | Manufacturing | 1996 |
| Tintoretto Ky | Manufacturing | 1981 |
| Tinttu Invest Oy | Professional & scientific | 1993 |
| Tip Top Shop Oy | Administrative & support | 2020 |
| TipTop Kalusteet Oy | Construction | 2021 |
| Tistron-Skatan vesiosuuskunta | Construction | 2017 |
| Tocando Oy | Financial services | 2022 |
| Toeboys Craft Oy | Wholesale & retail | 2018 |
| Toejoen Autohuolto Oy | Other services | 2019 |
| Toejoen Seurojentalo Oy | Other services | 1946 |
| Toejoen Sähköasennus Oy | Construction | 1993 |
| Toejoen Taimiala oy | Agriculture & fishing | 1993 |
| Toiminimen rekisteröinti on kumottu | Construction | 2007 |
| Toiminimi kumottu | Financial services | 2002 |
| Toimistopiste PT Ky | Professional & scientific | 1993 |
| Toinen Onni Oy | Professional & scientific | 1987 |
| Toiwo Care Oy | Arts & recreation | 2017 |
| Tom Mix Oy | Information & communication | 1979 |
| Tombcape & Tippler Oy | Information & communication | 2009 |
| Tonemakers Oy | Manufacturing | 2014 |
| Toni Peltonen From Pori Finland Oy | Information & communication | 2022 |
| Tonnitec Oy | Wholesale & retail | 2013 |
| Tony&Juha Service Oy | Real estate | 2022 |
| Top-Motor Oy | Wholesale & retail | 2005 |
| ToriGyne Oy | Financial services | 1987 |
| Trademan Oy | Financial services | 2023 |
| Training Studio Aqua Oy | Arts & recreation | 2016 |
| Treasury Consigliere Oy | Professional & scientific | 2023 |
| Trendit Kodit Rakennus Oy | Construction | 2019 |
| Treuding Oy | Arts & recreation | 2023 |
| TrioKauneus Oy | Wholesale & retail | 2014 |
| Troolari Nessie Oy | Agriculture & fishing | 1996 |
| TrueGem Value Oy | Manufacturing | 2020 |
| Trukkihuolto Ikonen Oy | Manufacturing | 2009 |
| Tuholaistorjunta Tuhotiimi Oy | Administrative & support | 2026 |
| Tuisku Laine Oy | Health & social care | 2026 |
| Tuki- ja valmennuspalvelu Luotsi Oy | Health & social care | 2021 |
| Tuki-Valkku Oy | Health & social care | 2020 |
| Tukkuliike Rantala Oy | Wholesale & retail | 2019 |
| Tulisiemen Oy | Wholesale & retail | 2022 |
| Tulkkaus- ja terapiapalvelu Kipinä Oy | Professional & scientific | 2024 |
| Tuomaa Oy | Households | 2016 |
| Tuonti-Petri Oy | Administrative & support | 1990 |
| Tuosti Oy | Professional & scientific | 2021 |
| Tuotetalo Oy | Real estate | 1995 |
| Tupla-Kontrolli Oy | Professional & scientific | 1990 |
| Turkistarha Arja ja Seppo Pyykkönen | Agriculture & fishing | 1982 |
| Turo's Heavy Oy | Hospitality | 2017 |
| Turun Kovakromi Oy | Manufacturing | 1989 |
| Turun Nauha ja Nappi Ky | Wholesale & retail | 1988 |
| Turvallisuuskeskus-Safety Center Oy | Financial services | 1973 |
| Tuttujuttu Oy | Information & communication | 1987 |
| Tuumasta Toimeen Toimitus Oy | Arts & recreation | 1990 |
| Tuure Boelius Oy | Arts & recreation | 2019 |
| Tuxport Oy | Real estate | 1989 |
| Tyltty-Oodee vesiosuuskunta | Professional & scientific | 1995 |
| Työkaluhionta Jussi Huovinen Ky | Manufacturing | 1990 |
| Työmies Korhonen Oy | Construction | 2020 |
| Työturvallisuuskonsultointi Villanen Oy | Professional & scientific | 2025 |
| Täckman Oy | Arts & recreation | 1996 |
| Tähti Consulting Ky | Professional & scientific | 2020 |