| Ingresso Oy | Helsinki | 2005 |
| Ingå förvaltning Ab - Inkoon arvo-osuudet Oy | Helsinki | 2006 |
| Inhaber Oy | Kangasala | 2005 |
| Initisor Oy | Helsinki | 1995 |
| Iniö Holding Oy | Turku | 2019 |
| Ink Living Oy | Paattinen | 2021 |
| Inkallio Oy | Helsinki | 2020 |
| Inkapital Partners Oy | Sastamala | 2025 |
| Inkaro Oy | Espoo | 2022 |
| Inkeroinen Invest Oy | Klaukkala | 2023 |
| Inki Investment Oy | Askola | 2026 |
| Inktoivo Oy | Oulu | 2022 |
| Inkvest Oy | Nurmijärvi | 2025 |
| Inmik Oy | Vesanka | 2023 |
| InnAava Oy | Tampere | 2022 |
| Innamo Invest Oy | Turku | 2025 |
| Inner Circle Oy | Turku | 2001 |
| Innestor Oy | Lohja | 2023 |
| InnoM Oy | Helsinki | 1991 |
| InnoPro Invest Oy | Helsinki | 2017 |
| Innoair Group Oy | Helsinki | 2023 |
| Innocap Oy Ab | Helsinki | 1997 |
| Innoflame Group Oy | Helsinki | 2021 |
| Innoflame Holding Oy | Helsinki | 2021 |
| Innoframe Oy | Vinkkilä | 2018 |
| Innoholding Oy | Vantaa | 2018 |
| Innollinen Oy | Tampere | 2025 |
| Innostella Inc Oy | Osoite Tuntematon | 2010 |
| Innotiimi Invest Oy | Tuusula | 2017 |
| Innovate Invest Oy | Vantaa | 2024 |
| Innovation Compound Partners Oy | Söderkulla | 2021 |
| Innovator Group Oy | Turku | 2024 |
| Innovestor CF GP Oy | Helsinki | 2023 |
| Innovestor Finance Oy | Helsinki | 2015 |
| Innovestor Kasvurahasto I Ky | Helsinki | 2016 |
| Innovestor Kasvurahasto II Ky | Helsinki | 2018 |
| Innovestor Kasvurahasto III Ky | Helsinki | 2023 |
| Innovestor LF GP Oy | Helsinki | 2021 |
| Innovestor Life Science Fund Ky | Helsinki | 2021 |
| Innovestor Life Science GP II Oy | Helsinki | 2026 |
| Innovestor Life Science Oy | Helsinki | 2021 |
| Innovestor Life Science Private Fund Ky | Helsinki | 2021 |
| Innovestor Oy | Helsinki | 2014 |
| Innovestor TF GP Oy | Helsinki | 2019 |
| Innovestor Technology Fund Ky | Helsinki | 2020 |
| Innovestor Ventures Oy | Helsinki | 2015 |
| Innovoittaja Oy | Piikkiö | 2002 |
| Inosence Oy | Tampere | 2016 |
| Inout Oy | Helsinki | 1983 |
| Insane Finance Oy | Kirkkonummi | 2023 |
| Insight Capital Oy | Espoo | 2025 |
| Insight Holding Oy | Jyväskylä | 2025 |
| Insinööritoimisto Fin-Lvi Oy | Klaukkala | 1999 |
| Insinööritoimisto Pirjetä Oy | Helsinki | 1978 |
| Insinööritoimisto Reseco Oy | Nokia | 1990 |
| Insinööritoimisto Riku Saarinen Oy | Askola | 2017 |
| Insinööritoimisto SK Oy | Turku | 1978 |
| Insinööritoimisto Tarmo Peltoniemi Oy | Pori | 1995 |
| Insinööritoimisto Timo Vasa Oy | Espoo | 1994 |
| Inspectum Group Oy | Huruksela | 2025 |
| Inspire Solutions Oy | Turku | 2014 |
| Instafin Oy | Helsinki | 2025 |
| Instantscore Oy | Espoo | 2019 |
| Instator Oy | Helsinki | 1991 |
| Instinctive Ventures Oy | Espoo | 2022 |
| Instman Group Oy | Nuppulinna | 2023 |
| Instrac Oy | Orimattila | 2006 |
| Insula Capital Oy | Helsinki | 2004 |
| Insula Consulting AB | Mariehamn | 2017 |
| Insulaex Oy | Helsinki | 2014 |
| Insurance House A & A OY | Kotka | 2015 |
| Insuranco Oy | Siilinjärvi | 2016 |
| Insvest Oy | Uusikaupunki | 2016 |
| Insync Oy | Helsinki | 2022 |
| InteRitus Holding Oy Ltd. | Turku | 2022 |
| Integra Capital Partners Oy | Helsinki | 2003 |
| Integrity Capital Oy | Helsinki | 2022 |
| Intensify Oy | Tampere | 2020 |
| Intera Equity Partners III Oy | Helsinki | 2016 |
| Intera Equity Partners IV Oy | Helsinki | 2021 |
| Intera Equity Partners V Oy | Helsinki | 2026 |
| Intera Fund III Ky | Helsinki | 2016 |
| Intera Fund IV Ky | Helsinki | 2021 |
| Intera Fund V Ky | Helsinki | 2026 |
| Intera Partners Oy | Helsinki | 2021 |
| Intera Scratch Co-Invest Ky | Helsinki | 2026 |
| Interbaltic Investments Oy | Espoo | 1992 |
| Interbau Oy | Espoo | 1990 |
| Intercomp Kommandiittiyhtiö | Helsinki | 1991 |
| Interconnected Ab | Kauniainen | 2021 |
| Interlab Oy | Helsinki | 1978 |
| International Family Investments Oy | Helsinki | 2016 |
| Internet palvelimet Oy | Vantaa | 1993 |
| Interno Oy | Helsinki | 1990 |
| Internos Partners Oy | Espoo | 2004 |
| Interval International Finland Oy | Espoo | 1996 |
| Intervalo-Invest Oy | Vantaa | 2020 |
| Intervalor Aktiebolag, sivuliike Suomessa | Helsinki | 2006 |
| Interventti Oy | Tampere | 2015 |
| Intexment Holding Oy | Turku | 2019 |