| Intecor Oy | Kempele | 2025 |
| Integr Holding Oy | Hämeenlinna | 2014 |
| Integra Expert Oy | Vantaa | 2025 |
| Integra Oy | Kuusisto | 1987 |
| Integral Foresight Finland Oy | Pori | 2019 |
| Integral Insights Oy | Siuntio | 2025 |
| Integrata Oy | Tampere | 2008 |
| Integrate Us Oy | Espoo | 2018 |
| Integren Oy | Sodankylä | 2025 |
| Integria Oy | Porvoo | 2026 |
| Integrify Oy | Helsinki | 2016 |
| Integrity Holding Oy | Helsinki | 2019 |
| Integrity valmennus- ja konsultointipalvelut Oy | Helsinki | 2023 |
| Integrum Ky | Turku | 1982 |
| Intekra Oy | Sauvo | 2020 |
| Intelco Oy | Kerava | 2003 |
| Intella Oy | | 1979 |
| Intellego Sales & Coaching Oy | Nuutajärvi | 2011 |
| Intellicons Oy | Helsinki | 2016 |
| Intelligence Factory Oy | Noormarkku | 2007 |
| Intelligencer Oy | Helsinki | 2026 |
| Intelligent Consulting Engineers OÜ Suomen sivuliike | Espoo | 2022 |
| Intelligent Diamond Oy | Pieksämäki | 2023 |
| Intelligent Employment OY | Helsinki | 2019 |
| Intellira Oy | Helsinki | 2010 |
| Intellis Oy | Jorvas | 2016 |
| Intellisys Oy | Helsinki | 1990 |
| Inteni Oy | Nokia | 2015 |
| Intentio Agency Oy | Helsinki | 2023 |
| Intentium Oy | Porvoo | 2002 |
| Intento Oy | Helsinki | 2022 |
| Inter Electric Oy | Espoo | 2012 |
| Inter Juris Ky | Helsinki | 1999 |
| Inter pares Oy | Pirkkala | 2019 |
| Inter-Gruppe Oy | Espoo | 1991 |
| Inter-Viihde Oy | Kuopio | 2014 |
| InterLaw Consulting Oy | Tampere | 2007 |
| Interactive Auto Media Oy | Espoo | 2008 |
| Interactive Inuits Oy | Helsinki | 2009 |
| Intercast Oy Ab Ltd | Espoo | 1986 |
| Intercession Oy | Espoo | 1985 |
| Intercircum Oy | Oulu | 2007 |
| Interfast Oy | Espoo | 1987 |
| Interform Oy | Helsinki | 2019 |
| Intergeo Fennica Oy | Helsinki | 1993 |
| Interi Oy | Osoite Tuntematon | 2023 |
| Interim CEO Oy | Seinäjoki | 2022 |
| Interim Executive Services Oy | Riihimäki | 2021 |
| Interim Impact Oy | Klaukkala | 2022 |
| Interim Legal & Leadership Oy | Helsinki | 2023 |
| Interim Program Management Oy | | 2023 |
| Interim Sales Oy | Helsinki | 2013 |
| Interim Services Ab | Helsinki | 2018 |
| InterimEx Oy | Nummela | 2011 |
| Interior Design Helena Karihtala Oy | Helsinki | 2007 |
| Interior Design Helsinki Oy | Vantaa | 2021 |
| Interior Design Latvalahti Oy | Espoo | 2022 |
| Interior Design Seija Strand Oy | Helsinki | 2020 |
| Interior House Oy | Helsinki | 2019 |
| Interior Ida Ilkko Oy | Helsinki | 2023 |
| Interior Photography AN Oy | Vantaa | 2015 |
| Interior SmArt Deco Oy | Kuopio | 2019 |
| Interior de la casa Oy | Jyväskylä | 2021 |
| Interiora Consilia Oy | Vantaa | 2024 |
| Interiori Oy | Tampere | 2023 |
| Interium Oy | Sauvo | 2023 |
| Interix Oy | Vantaa | 1993 |
| Interlaser Oy | Joutseno | 2014 |
| Interleaf Oy | Espoo | 1989 |
| Interlink Oy | Savonlinna | 1996 |
| Interlock Oy | Helsinki | 1986 |
| International Artist Center Oy | Sulkava | 1964 |
| International Cleantech Ventures Finland Oy | Helsinki | 2012 |
| International Digital Solutions Oy | Helsinki | 2015 |
| International Forest Advisors Oy | Lahti | 2024 |
| International Fox Agency Oy | Helsinki | 2019 |
| International Industry Service Company Oy | Helsinki | 2024 |
| International Law Georg Gustav Wrangel Oy | Helsinki | 2010 |
| International Law Scandinavia Oy | Helsinki | 2024 |
| International Legal Service BNK Oy | Helsinki | 2012 |
| International Market Development Agency Oy | Helsinki | 2020 |
| International Project Services Ltd. Oy | Espoo | 1980 |
| International Radiation Expert Services Oy | Helsinki | 2025 |
| International TCI Projects Oy | Littoinen | 2023 |
| International Talent Management Company ITMC Oy | Vantaa | 2013 |
| International Trade Service ITS Oy | Espoo | 2011 |
| Interniemi Oy | Helsinki | 2006 |
| Interpress Oy Finland | Lohja | 1996 |
| Interpublic Finland Oy | Helsinki | 2008 |
| Interring Oy | Lahti | 1980 |
| Intersearch Oy | Helsinki | 2006 |
| Interteam Oy | Espoo | 1975 |
| Intertek Finland Oy | Helsinki | 2004 |
| Intertek Medical Notified Body AB Suomen sivuliike | | 2019 |
| Intervisio Holding Oy | Helsinki | 1998 |
| Intervox Research Oy | Espoo | 1998 |
| Interware Oy | Helsinki | 1987 |
| Intery Oy | Helsinki | 2022 |
| Interzero Finland Oy | Helsinki | 2026 |
| Inticon Oy | Espoo | 1990 |