| Insinööritoimisto Nordlund Oy | Osoite Tuntematon | 1989 |
| Insinööritoimisto Petri Hukki Oy | Riitiala | 1987 |
| Insinööritoimisto Pirttimäki Oy | Pori | 2024 |
| Insinööritoimisto Rakenne-Laukkanen Oy | Järvenpää | 1995 |
| Insinööritoimisto Simulainen Oy | Tampere | 2025 |
| Insinööritoimisto Tammercad Oy | Tampere | 1984 |
| Inskriptio Oy | Kuopio | 2024 |
| Insolitus Oy | Jyväskylä | 2020 |
| Insomniac Oy | Kuopio | 2004 |
| Insoniq Avoin Yhtiö | Hyvinkää | 2002 |
| InspectWise Oy | Helsinki | 2022 |
| Inspia Oy | Renko | 2007 |
| Inspiring Business Oy | Oulu | 2023 |
| Inspiroiva Creative Oy | Lahti | 2018 |
| Inspot Oy | Lemi | 2026 |
| Insta Advance Oy | Tampere | 2000 |
| Install L Group Oy Ltd | Lieto | 2001 |
| Instance Oy | Oulu | 2022 |
| Instructio Oy | Espoo | 2024 |
| Instrumental Consulting Oy | Osoite Tuntematon | 2019 |
| Insured Oy | Helsinki | 2020 |
| Insurro Oy | Espoo | 2021 |
| Insynergi Oy | Osoite Tuntematon | 2020 |
| Integral Oy | Espoo | 2005 |
| Integrated E-Solutions Finland Oy | Vantaa | 2000 |
| Integration Technologies Nordic Oy Ab | Kauniainen | 2000 |
| Integrations Group Oy | Helsinki | 2020 |
| Integratis Oy | Helsinki | 2021 |
| Integritas Oy | Tuusula | 2012 |
| Integrity Consulting Oy | Espoo | 2018 |
| Integroi Systems Oy | Rantasalmi | 2026 |
| Integround Oy | Kerava | 2012 |
| IntelTek AI Oy | Espoo | 2018 |
| Intellectual Farms Oy | Osoite Tuntematon | 2019 |
| Inteller Tech Oy | Helsinki | 2026 |
| IntelliNord Oy | Vaajakoski | 2019 |
| Intellica Solutions Oy | Palokka | 2002 |
| Intelligence Engineering Systems Oy | Elimäki | 1978 |
| Intelligent Asset Management Oy | Muonio | 2023 |
| Intelligent HR Systems Finland Oy | Kirkkonummi | 1988 |
| Intelligent Machine RPA Oy | Vantaa | 2020 |
| Intelligent Solutions Finland Oy | Helsinki | 2021 |
| Intelligent Systems Oy Finland | Espoo | 1992 |
| Intelligent Vantage Oy Ltd | Espoo | 2021 |
| Intellioris Oy | Pirkkala | 2026 |
| Intellipocket Oy | Espoo | 2009 |
| Intellisolv Oy | Vantaa | 2003 |
| Intelwings Oy | Lappeenranta | 2023 |
| IntentForm Oy | Espoo | 2025 |
| Intentface Oy | Turku | 2023 |
| Intentum Oy | Helsinki | 2013 |
| Inteq Oy | Espoo | 2019 |
| InterDigital Finland Oy | | 2020 |
| InterLunix Oy | | 2014 |
| InterTechno Training Oy | Vantaa | 2011 |
| Intera Software Oy | Turku | 2000 |
| Interacta Design Oy | Helsinki | 1999 |
| Interactiva Solutions Ky | Vantaa | 2003 |
| Interactive Online Technologies Oy | Vantaa | 2021 |
| Interactive Slide Solutions Oy | Järvenpää | 2023 |
| Interant Oy | Järvenpää | 2020 |
| Intercut Pictures Oy | Helsinki | 2022 |
| Interfilm Oy | Nurmijärvi | 2013 |
| Intergalactic Sound and System Engineering Oy | Oulu | 2024 |
| Intergrid Oy | Helsinki | 2023 |
| Interior Intelligence Oy | Fiskari | 2023 |
| Interjektio Oy | Oulu | 2019 |
| Interlinear Oy | Helsinki | 2025 |
| International Artist Sounds Lux Oy | Helsinki | 2020 |
| International Artist Sounds Oy | Helsinki | 2020 |
| International Data center Oy | Seinäjoki | 2020 |
| International Methelp Oy | Vantaa | 2000 |
| International Rescue Organization Ab | Mariehamn | 2016 |
| International Software Planners Skandinavia Oy | Turku | 1992 |
| International Vlogs Oy | Helsinki | 2025 |
| Internerds Oy | Pirkkala | 2022 |
| Internet Imperiumi Oy | Helsinki | 2013 |
| Internext Oy | Vantaa | 2022 |
| Internexus Oy | Helsinki | 2010 |
| Interop Oy | Vantaa | 2018 |
| Interque Oy | Helsinki | 2010 |
| Intersolia Oy | Helsinki | 2024 |
| Intersystems B.V. sivuliike Suomessa | Espoo | 2000 |
| Intervisio Oy | Helsinki | 2022 |
| Interweave Oy | Helsinki | 2026 |
| Interzone Oy | Kempele | 2019 |
| Into Films Oy | Helsinki | 2024 |
| Into Kustannus Oy | Helsinki | 2007 |
| Into Productions Oy | Vantaa | 2023 |
| Into Security Oy | Espoo | 2024 |
| Intodata Oy | Vaasa | 2022 |
| Intoloop Oy | Tampere | 2009 |
| Intragen Oy | Helsinki | 2015 |
| Intresa Ventures Oy | Helsinki | 2013 |
| Intrinsic Oy | Tampere | 1984 |
| IntroTech Oy | Helsinki | 2016 |
| Introinnovation Oy | Helsinki | 2019 |
| Introist Oy | Rovaniemi | 2022 |
| Intu Enterprises Oy | Helsinki | 2021 |
| Intuitio Oy | Turku | 2021 |