Mjölby Municipality, Administrative municipality in Östergötland County, Sweden

Mjölby Municipality lies in Östergötland County, with Mjölby as its seat. The northern part is flat farmland on the Östgöta plain, while the south is covered by coniferous forest. In the west lies Tåkern, one of Sweden's best-known bird lakes. The municipality was formed in 1971 from the cities of Mjölby and Skänninge and surrounding rural areas.

Mjölby Municipality was formed in 1971 from the City of Mjölby, the City of Skänninge, Vifolka rural municipality, and parts of Boberg and Folkunga. Mjölby had become a city in 1920, and Skänninge was one of Sweden's medieval towns. Since 2002 the municipality has belonged to Linköping's judicial district.

The municipality maintains specialized educational institutions, including a goldsmith school and an engine driver training facility, contributing to regional skill development.

The area is accessible by car and public transport that connect the different localities. Most local services and facilities are concentrated in the town centers of Mjölby and Skänninge.

The municipality's twin-city agreements link it with Karmøy in Norway, Hankasalmi in Finland, Häädemeeste in Estonia, and Rudkøbing and Slangerup in Denmark. The Swedish source lists only the first three, while the English source adds the two Danish towns.