Kungsör Municipality, Municipal government center in Västmanland County, Sweden

Kungsör Municipality is a municipality in Västmanland County, central Sweden, with its seat in the town of Kungsör at the western end of Lake Mälaren. The landscape is open, dominated by fields and meadows, and includes the localities of Kungsör and Valskog. The municipality was formed in 1971 from Kungsör and Kung Karl.

Kungsör grew around a royal mansion built by King Gustav Vasa in the 16th century, parts of which still stand on a cape in Lake Mälaren. It became a köping (market town) in 1907 after being detached from Kung Karl, and in 1971 the köping merged with Kung Karl to form the present municipality.

The municipality maintains international relations through a sister city partnership with Spydeberg, Norway, promoting regional cultural exchanges and cooperation.

Kungsör Municipality is crossed by European routes E18 and E20 and by national road 56, so the main settlements are reached by road. The seat, Kungsör, lies on a cape in the western end of Lake Mälaren, with Valskog as the other main locality. The Köpingsåsen esker runs north-south through the town of Kungsör and along the lake's western shore.

The royal mansion that Gustav Vasa built in the 16th century stood on a cape jutting into Lake Mälaren, and parts of it are still preserved and open to visitors. The town of Kungsör grew up around this building.