We applied integrated lithospheric modeling combining the interpretation of surface heat flow, geoid, gravity, and topography data for the determination of the lithospheric thermal structure along four transects crossing the eastern Carpathians from the European Platform to the Pannonian Basin and propose a new map of lithospheric thicknesses. Important differences in lithospheric thickness across the chain as well as along strike of the Carpathian arc exist. Lithosphere thickness varies from 240 km in the foreland to 75–110 km, under the Pannonian Basin and it increases from the western to the eastern Carpathians. Under the western segment of the western Carpathians (in the transition zone to the eastern Alps), no thickening is observed, which may be explained by a mainly strike-slip movement between the European and Carpatho-Pannonian plates. Thickened lithosphere is found NE of thickened crust under the Carpathians. This observation is in agreement with slab roll-back and possible subsequent break-off.