| 3S Solutions Oy | Administrative & support | 2014 |
| A Luukko Oy | Administrative & support | 2021 |
| A. Haarla Oy | Real estate | 1967 |
| A. Kortemäki Ky | | 1974 |
| Aerotekniikka UAV Oy | Professional & scientific | 2011 |
| Ahavus Oy | Hospitality | 2020 |
| Ahinmäen Konepalvelu Oy | Construction | 2006 |
| Akira Invest Oy | Manufacturing | 1987 |
| Applesin Oy | Professional & scientific | 2010 |
| Aristo Management Oy | Professional & scientific | 2026 |
| Autohuolto Auterinen Oy | Other services | 2021 |
| Autopaja Mikkola Ky | Other services | 1981 |
| Avoin yhtiö Puunkorjuu Jouko Salonen | Agriculture & fishing | 2005 |
| Betsau Ky | Construction | 2009 |
| Biovoima Jämsä Oy | Water & waste | 2008 |
| Bobcat-Urakointi M. Kyllästinen Oy | Construction | 2006 |
| Brainbody Oy | Professional & scientific | 1989 |
| Building Inspectors Oy | Professional & scientific | 2020 |
| CM Viiki Oy | Professional & scientific | 2017 |
| Cafe & Trattoria Cedro Oy | Hospitality | 2026 |
| Coating Source Oy | Professional & scientific | 2006 |
| Daniel Ramzi Oy | Hospitality | 2024 |
| Dorn Terapia Gartmann OY | Other services | 2021 |
| Erkki Salminen Oy | Water & waste | 1979 |
| FarmaFamily Oy | Wholesale & retail | 2010 |
| Farqin Oy | Hospitality | 2022 |
| Finnrustica Oy | Real estate | 2024 |
| Frostila Oy | Agriculture & fishing | 2009 |
| General Way Pub Ky | Hospitality | 2023 |
| Genencor International Oy | Manufacturing | 1989 |
| Geraser Oy | Professional & scientific | 2021 |
| GlitterBomb Oy | Hospitality | 2021 |
| HEMI Yhtiöt Oy | Construction | 2017 |
| HHA Expediting and Inspection Services Oy | Professional & scientific | 2021 |
| HMR-Kuljetus Ky | | 1986 |
| HPY-Kiinteistöt Oy | Construction | 2008 |
| HR Rock-Rock Oy | Real estate | 1996 |
| HT-Trotting Oy | Agriculture & fishing | 2018 |
| Hiekkapuhallus Yhtymä H & H Oy | Construction | 1988 |
| Ikipihlaja Johanna Oy | Health & social care | 2007 |
| Ilmapiste Ky | Construction | 1986 |
| JL-Hydro Oy | Construction | 2019 |
| JM Tarkastus- Ja Huoltopalvelu OY | Other services | 2025 |
| JOKIKO Oy | Real estate | 2014 |
| JSK-Forest Oy | Agriculture & fishing | 2025 |
| JSO International Export Oy | Financial services | 2005 |
| Jalan Maansiirto Oy | Construction | 2020 |
| JettVision Security Systems Oy | Administrative & support | 2024 |
| Jokilaakson Murskaus Oy | Mining & quarrying | 1982 |
| Jokinen Systems Oy | Other services | 2023 |
| Jämsän Kello ja Koru Näräkkä Ky | | 1982 |
| Jämsän Kuva Oy | Professional & scientific | 2015 |
| Jämsän Maalimestarit Ky | Construction | 1991 |
| Jämsän Metalli ja Kuljetus Oy | Construction | 1993 |
| Jämsän Seudun Taksipalvelu Oy | Transport & logistics | 2012 |
| Jämsänkosken Autopurkaamo Ky | Wholesale & retail | 1989 |
| Jämsänkosken Fysikaalinen Hoitolaitos Oy | Health & social care | 1981 |
| Jämsänkosken Kuljetus ja Huolto Järvi Oy | Wholesale & retail | 1996 |
| Jämsänkosken Kuntoutus Oy | Health & social care | 1988 |
| Jämsänkosken Motovaruste Oy | Manufacturing | 1991 |
| Jämsänkosken Tekojäärata Oy | Real estate | 1998 |
| Jämsänkosken Teräsvalmiste Oy | Manufacturing | 2014 |
| Jämsänkosken linna Oy | Arts & recreation | 2023 |
| KBT Yhtiöt Oy | Construction | 2025 |
| KBT-Rakennus Oy | Construction | 2015 |
| KEO Universal Export Oy | Health & social care | 2021 |
| KS-Tarkastajat Oy | Professional & scientific | 2026 |
| Kapteeni Ravintola Oy | Hospitality | 2025 |
| Keski-Suomen Sauna ja Rakennus Oy | Construction | 2024 |
| Keuruun RM Rakennus Oy | Construction | 1993 |
| Kiinteistö Oy Jämsänkosken Kisällintie 1 | Real estate | 2002 |
| Kiinteistö Oy Konilankulma | Real estate | 1991 |
| Kiinteistö Oy Myllyharju 3, Jämsä | Real estate | 2016 |
| Kiinteistöosakeyhtiö Vanha Paja Oy | Real estate | 2023 |
| Kolhon Valinta Jokeri Jouko ja Paula Mäkelälammi | Wholesale & retail | 1991 |
| Koneurakointi Imberg Oy | Construction | 1988 |
| Kosken Autoliike Avoin Yhtiö | Wholesale & retail | 1965 |
| Kosken Painopalvelu Ky | | 1987 |
| Koski-Steel Ky | Professional & scientific | 1990 |
| Kotisairaanhoito Kesäheinä Oy | Health & social care | 2020 |
| Kotitalli Oy | Real estate | 1993 |
| Kouru ja Kaihdin Center Oy | Construction | 2007 |
| KukkaWalo Oy | Wholesale & retail | 2009 |
| Kuljetus A. Lehti Oy | Transport & logistics | 2004 |
| Kuljetus Kelander Oy | Transport & logistics | 2020 |
| Kuljetus Seppo Mäkinen Oy | Transport & logistics | 1991 |
| Kuljetus Silván & Järvenpää Oy | Transport & logistics | 2008 |
| Kuljetus- ja Koneurakointi Jokinen Oy | Transport & logistics | 1979 |
| Kulttuurilinna Oy | Arts & recreation | 2025 |
| Kunnon Ässä Oy | Arts & recreation | 2025 |
| L&H-Mekaniikka Jometa Oy | Manufacturing | 1989 |
| LVI-Viritys Oy | Construction | 1986 |
| Laaksosen Autokorjaamo Ky | Other services | 1953 |
| Lubritec Oy | Wholesale & retail | 1992 |
| MKK - Eristys ja Huolto Oy | Construction | 2019 |
| Markkinointi P. Kaunisto Ky | Wholesale & retail | 1989 |
| Medelfix Oy | Other services | 1991 |
| Menucat Oy | Hospitality | 2005 |
| Metsänova Oy | Health & social care | 2018 |
| Minimalisti Oy | Information & communication | 2010 |