 After Ivan III annexed the principality to the Grand Duchy of Moscow in 1493, local princes emigrated either to the Grand Duchy of Lithuania (where they became known as Princes Massalski) or to Moscow (where they were known as Princes Koltsov-Mosalsky).Mosalsk was granted town status within Kaluga Governorate in 1776.Within the framework of administrative divisions, Mosalsk serves as the administrative center of Mosalsky District, to which it is directly subordinated.