On the north, Birstein borders on Grebenhain, which lies in the Vogelsbergkreis, and on the east, its neighbors are Freiensteinau (also in the Vogelsbergkreis) and the town of Steinau an der Straße.
The separation of Bösgesäß I (Prussian Bösgesäß) and Bösgesäß II (Hessian Bösgesäß) took place as a result of the Congress of Vienna.