Linnasenmäki, the remains of an Iron Age hillfort, are located in the southern part of Jämsänkoski near the paper mill.

[2] Jämsänkoski was originally only the name of the rapids in the Jämsänjoki river.

[3] Paper production started in 1888, when Elieser Johansson and Per Benjamin Köhlin established a cellulose factory in the area.

Jämsänkoski got its own parish in 1925 and became a separate municipality in 1926.

The paper mill owned by UPM Kymmene is the largest employer of Jämsänkoski.