| United Grinders Oy | Manufacturing | 2020 |
| Universaalit studiot Oy | Information & communication | 2007 |
| Universal Fitness Shop Oy | Wholesale & retail | 1996 |
| Universum Communications Sweden Aktiebolag Finland Filial | Professional & scientific | 2010 |
| Univire Oy | Other services | 2019 |
| Uniwaves Oy | Professional & scientific | 2002 |
| Uniwerzum Group Oy | Professional & scientific | 2023 |
| Unixad Oy | Professional & scientific | 2025 |
| Unlimited Limited Oy | Administrative & support | 2025 |
| Unlit Films Oy | Information & communication | 2013 |
| Unmac Oy | Professional & scientific | 2021 |
| Unna Invest Oy | Professional & scientific | 2020 |
| Unnanenna Oy | Financial services | 2022 |
| Uno Mas Collection Oy | Wholesale & retail | 2015 |
| UnoCare Avoin yhtiö | Health & social care | 2019 |
| Unovest Oy | Financial services | 2026 |
| Unskin Ykkösasunnot Oy | Administrative & support | 2024 |
| Uoma Infra Oy | Information & communication | 2026 |
| Uoma Mind Oy | Information & communication | 2024 |
| Uomagrit Oy | Information & communication | 2026 |
| Uosukainen Capital Oy | Financial services | 2011 |
| Up 2 Date Oy | Professional & scientific | 2003 |
| Upfound Oy | Information & communication | 2025 |
| Upisami Oy | Construction | 2007 |
| Upknowledge Oy | Information & communication | 1995 |
| Uplift Medical Oy | Health & social care | 2026 |
| Uppsidan Oy Ab | Information & communication | 2020 |
| Upswing Consulting Oy | Professional & scientific | 2019 |
| Ura Solutions Oy | Information & communication | 2015 |
| Uralab Oy | Professional & scientific | 2025 |
| Urania Capital Oy Ab | Financial services | 2025 |
| Urapolku Oy | Professional & scientific | 2023 |
| Urban Kitchen Oy | Wholesale & retail | 2023 |
| Urban TRC Oy | Hospitality | 1996 |
| UrbanTed Oy | Administrative & support | 2016 |
| Uretaani-Team Oy | Construction | 1983 |
| Urhak oy | Construction | 2023 |
| Urheilu-Vuoksi Ky | Wholesale & retail | 1984 |
| Urheilukaverit oy | Arts & recreation | 2003 |
| Urhon eläin Oy | Wholesale & retail | 2002 |
| Urisens Oy | Professional & scientific | 2025 |
| Urkka & Kumpp kommandiittiyhtiö | Transport & logistics | 1962 |
| Urku Oy | Wholesale & retail | 2026 |
| Urmest Oy | Construction | 2022 |
| Uronostics Oy | Professional & scientific | 2020 |
| Uroteko Oy | Health & social care | 2007 |
| Urpoerämies Productions Oy | Information & communication | 2021 |
| Ursus Energy Oy | Professional & scientific | 2014 |
| Us-miljö Oy | Wholesale & retail | 1993 |
| Usama Enterprises Oy | Transport & logistics | 2024 |
| Uski Consulting Oy | Health & social care | 2005 |
| Uskon Sanan Kustannus Oy | Information & communication | 1982 |
| Usva DC Projects Oy | Financial services | 2026 |
| Usva Developing Oy | Energy | 2025 |
| Usva Energia Oy | Energy | 2024 |
| Usva Energy Storage Arkkukallio Oy | Energy | 2026 |
| Usva Energy Storage Honkamäki Oy | Energy | 2026 |
| Usva Energy Storage Kitee Oy | Energy | 2025 |
| Usva Energy Storage Kouvola Oy | Energy | 2025 |
| Usva Energy Storage Kuopio Oy | Energy | 2025 |
| Usva Energy Storage Lieksa Oy | Energy | 2025 |
| Usva Energy Storage Mikka Oy | Energy | 2025 |
| Usva Energy Storage Pieksämäki Oy | Energy | 2025 |
| Usva Energy Storage Salo I Oy | Energy | 2025 |
| Usva Energy Storage Salo II Oy | Energy | 2025 |
| Usva Energy Storage Varkaus Oy | Energy | 2025 |
| Usva Invest Oy | Financial services | 2025 |
| Usva Lands Oy | Real estate | 2026 |
| Usva Outdoors Oy | Administrative & support | 2025 |
| Usva Projects Oy | Energy | 2025 |
| Usva Venture Oy | Financial services | 2025 |
| Utajärven Solarpark Oy | Energy | 2022 |
| Uterak Oy | Construction | 1998 |
| Utopia Development Oy | Administrative & support | 2025 |
| Utopia Investment Oy | Financial services | 2005 |
| Utopia Medical Oy | Health & social care | 2021 |
| Utoquai Equities Oy Ab | Financial services | 2023 |
| Utsova Oy | Information & communication | 2023 |
| Utu Rental Oy | Construction | 2023 |
| Uu Jee Oy | Hospitality | 2021 |
| Uudenmaan Aikuiskoulutuskeskus Oy | Education | 2011 |
| Uudenmaan Autovälitys Oy | Wholesale & retail | 2021 |
| Uudenmaan Duunarit Oy | Administrative & support | 2019 |
| Uudenmaan Hankintapalvelut Oy | Professional & scientific | 2008 |
| Uudenmaan Höyrypesu Oy | Other services | 2026 |
| Uudenmaan Kaihdin Group Oy | Wholesale & retail | 2026 |
| Uudenmaan Kotinäytteenotto Oy | Health & social care | 2015 |
| Uudenmaan Kunnostaja Oy | Construction | 2019 |
| Uudenmaan Kylmävaunu Oy | Wholesale & retail | 2023 |
| Uudenmaan Lumityöt Oy | Financial services | 2021 |
| Uudenmaan Marttapalvelut Oy | Education | 2022 |
| Uudenmaan Notariaattipalvelu Oy | Real estate | 1993 |
| Uudenmaan Palvelut Oy | Transport & logistics | 2023 |
| Uudenmaan Porrassiivous Oy | Administrative & support | 2021 |
| Uudenmaan Rakennus-Center Oy, URC | Professional & scientific | 2009 |
| Uudenmaan Rakennuskolmio OY | Construction | 2019 |
| Uudenmaan Rakennusmestarit Oy | Professional & scientific | 2022 |
| Uudenmaan Rakennustekniikka Oy | Construction | 1989 |
| Uudenmaan Rengashotelli Oy | Other services | 2025 |
| Uudenmaan Siivous- ja Kiinteistöhoitopalvelut Oy | Administrative & support | 2010 |