The town is located between the lakes Dämeritzsee, a part of the river Spree, and Flakensee, surrounded by a mainly forested landscape.

Neighbouring municipalities are Woltersdorf in the north, Grünheide (Mark) in the east, Gosen-Neu Zittau in the south and Berlin in the west.

In 1752, Prussian king Friedrich II installed a Mulberry plantation with 1,500 trees, of which only one is still standing in today's Friedrichstraße.

The industrialisation of Erkner began in 1860 with the founding of the first Continental European tar production unit by Julius Rütgers.

From 1885 to 1889 the German writer and later Nobel laureate Gerhard Hauptmann lived in Erkner, incorporating several local people and places into his stories.

On June 6, 1998 Erkner was the first town in Eastern Germany to be granted city rights after the German Reunification.