The present municipality was formed in 1971 through the amalgamation of the City of Flen (instituted in 1949), the market town (köping) Malmköping and the surrounding countryside, including a southeastern portion of the former Oppunda hundred that was split between Flen and Nyköping municipalities. It also includes all of the former Villåttinge hundred.
The present municipality was formed in 1971 through the amalgamation of the City of Flen (instituted in 1949), the market town (köping) Malmköping and the surrounding countryside, including a southeastern portion of the former Oppunda hundred that was split between Flen and Nyköping municipalities. It also includes all of. the former Villåttinge hundred.