Eisenberg is a municipality in the district of Ostallgäu, in the German state of Bavaria. It lies in the Allgäu region of southern Bavaria, within the administrative district of Swabia.
As a municipality, Eisenberg forms part of the local administrative structure of the Ostallgäu district, one of Bavaria's rural districts. The surrounding area is characterised by the landscapes typical of the Allgäu, a region known for its Alpine foothills and countryside.
Eisenberg should not be confused with other places of the same name in Germany, including the town of Eisenberg in Thuringia and the municipality of Eisenberg in Rhineland-Palatinate.