The municipality had a population of 975 (2006) and covered an area of 392.61 km2 of which 24.58 km2 is water.

Pylkönmäki was first mentioned in 1788, at the time referring to a farm in the village of Paajala.

It is named after Antti Pylkkänen (or Pylkkinen), who moved from Tavastia into the Karanka wilderness, where the village of Paajala would later appear.

In 1858 its inhabitants requested the establishment of a chapel in the settlement of Pylkönmäki, which is located between the villages of Paajala and Kukko.

The Finnish senate decided that Pylkönmäki should become a separate parish and municipality in 1898, but the change only happened later in 1914.