A short distance to the south of the old Sorbian village of Altforst, the town probably originated around 1150 at a river crossing point on the important west–east trade route.

The commercial importance of Forst increased with the development of a north–south route connecting to Guben, downstream along the Neisse River.

At various times the town was under the suzerainty of Bohemian, Hungarian, Saxon and Polish monarchs.

During World War II, in 1942–1943, the Germans operated a forced labour camp for Jewish men in the town.

Forst has experienced severe problems as a result of the 1990 German reunification, most notably from extreme unemployment.