| Taloagentit Oy | Construction | 2020 |
| Taloasema Oy | Real estate | 2009 |
| Talohotelli Oy | Real estate | 2023 |
| Taloisa Oy | Real estate | 2011 |
| Talokaivo Oy | Manufacturing | 2006 |
| Talokauppa24 Ky | Construction | 2012 |
| Talokuntoon.fi Oy | Administrative & support | 2016 |
| Talolasi Helsinki Oy | Manufacturing | 2025 |
| Talolasi Suomi Oy | Construction | 2026 |
| Talomyynti Jarkko Rossi Oy | Wholesale & retail | 2018 |
| Talon Piste Oy | Construction | 2023 |
| Talon maalaus Uusimaa Oy | Construction | 2023 |
| Talonuotit Oy | Administrative & support | 2007 |
| Talopalvelu J Majasalmi Oy | Wholesale & retail | 1986 |
| Talopiste Timo Majasalmi Ky | Wholesale & retail | 1987 |
| Talotakomo Oy | Professional & scientific | 2001 |
| Talotekniikka Eräpuro & Karjalainen Oy | Construction | 1993 |
| Talotekniikka Lavikainen Oy | Financial services | 2017 |
| Talotekniikka Mijorak Oy | Construction | 2007 |
| Talotieto Oy | Professional & scientific | 1977 |
| Taloturva Talotekniikka Oy | Construction | 2017 |
| Talous Tuiskut Oy | Real estate | 2026 |
| Taloushallinnon palvelutoimisto Jääskeläinen Oy | Professional & scientific | 1989 |
| Taloushallinta Kameleontti Oy | Professional & scientific | 2015 |
| Taloushallinto Koskelin Oy | Administrative & support | 2020 |
| Taloushallintopalvelut Officium Oy | Professional & scientific | 2022 |
| Talousosaajat Soini Oy | Professional & scientific | 2013 |
| Talouspalvelut HE Oy | Professional & scientific | 2020 |
| Talousrakenne Oy | Construction | 1984 |
| Taloveikot Oy | Transport & logistics | 1978 |
| Talowatti Oy | Construction | 2024 |
| Talvensaari Solutions Oy | Information & communication | 2013 |
| Talvi Asunnot Oy | Real estate | 2020 |
| Talvikaima Oy | Real estate | 2016 |
| Tamacos Oy | Manufacturing | 2002 |
| Tamcare Oy | Health & social care | 2024 |
| Tameara Oy | Professional & scientific | 2006 |
| Tamer Med Oy | Health & social care | 2024 |
| Tamm Invest Oy | Manufacturing | 1992 |
| Tammenterho Solutions Oy | Wholesale & retail | 2019 |
| Tammifoods Oy | Wholesale & retail | 2021 |
| Tammio Team Oy | Arts & recreation | 2007 |
| Tammisto Catering Oy | Hospitality | 2018 |
| Tammisto Consulting Oy | Health & social care | 2015 |
| Tammisto Design Oy | Wholesale & retail | 2024 |
| Tammiston Burger Oy | Hospitality | 2002 |
| Tammiston Kodit Oy | Construction | 2017 |
| Tammiston Talotekniikka Oy | Construction | 2025 |
| Tammiston höyrypesu oy | Administrative & support | 2019 |
| Tamoline Finland Oy | Wholesale & retail | 1999 |
| Tamri Talot Oy | Construction | 2026 |
| Tamro Oyj | Wholesale & retail | 1983 |
| TanTin-palvelut Oy | Administrative & support | 2023 |
| Tandem Investment Oy | Real estate | 1978 |
| Tandoori Villa Valmisruoka Oy | Hospitality | 2023 |
| Tanelin Kylpyhuoneremontit Oy | Construction | 2019 |
| Taneline Ab | Real estate | 2011 |
| Tanelinnova Oy | Construction | 2021 |
| Tanen-Service Oy | Administrative & support | 2016 |
| Tanera Oy | Construction | 2000 |
| Tanero Oy | Other services | 2022 |
| Tankkauspartio Oy | Wholesale & retail | 1997 |
| Tanora Oy | Construction | 2004 |
| Tanssifysio Oy | Health & social care | 2020 |
| Tanssikoulu Shufflers Oy | Education | 2023 |
| Tanssivat Saxet Oy | Other services | 1994 |
| Tanttorit Oy | Wholesale & retail | 2007 |
| Taore Oy | Real estate | 1990 |
| Tapaamistehdas Oy | Administrative & support | 2024 |
| Tapahtuma Sähkö Oy | Construction | 2007 |
| Tapahtuma-Aurinko Oy | Professional & scientific | 1989 |
| Tapahtuman vesi- ja putkipalvelu TVPP Oy | Professional & scientific | 2008 |
| Tapasya Oy | Professional & scientific | 2023 |
| Tapio Automotive Oy | Professional & scientific | 2020 |
| Tapio Sales & Consulting Oy | Professional & scientific | 2019 |
| Tapli Oy | Information & communication | 2026 |
| Tapora Oy | Wholesale & retail | 2026 |
| Tappuri Oy | Real estate | 1991 |
| Tapwell Oy | Wholesale & retail | 2010 |
| Targenta Oy | Information & communication | 2024 |
| Tarinapaja Oy | Arts & recreation | 2017 |
| Tarinapata Oy | Hospitality | 2008 |
| Tarja Muikku LKV Oy | Real estate | 2020 |
| Tark-Por Oy | Manufacturing | 1982 |
| Tarkastus- ja Kunnossapitopalvelut MPK Oy | Manufacturing | 2019 |
| Tarkastustekniikka Pauli Levy Oy | Professional & scientific | 1989 |
| Tarkka huolto Oy | Administrative & support | 2023 |
| Tarkkanen TJ Oy | Health & social care | 1994 |
| Tarlataani Oy Tarja Laanti | Professional & scientific | 1996 |
| Tarman Oy | Construction | 2020 |
| Tarmex | Construction | 2025 |
| Tarmite Holding Oy | Financial services | 2026 |
| Tarmo Linden Oy | Financial services | 1987 |
| Tarramesta Oy | Professional & scientific | 2025 |
| Tasapään Kiinteistöhuolto Oy Ltd | Administrative & support | 1993 |
| Tasavahvat Oy | Health & social care | 2021 |
| TasePro Oy | Professional & scientific | 2025 |
| Tasetalo Oy | Professional & scientific | 1977 |
| Tasita Building Oy Ltd | Construction | 2019 |
| Tasku Wakame Oy | Hospitality | 2022 |