Willmar is a city in, and the county seat of, Kandiyohi County, Minnesota, United States. The population was 21,015 at the 2020 census.

Agricultural expand and the foundation of Willmar as a disaffection point upon the Great Northern Railway positive its growth. The first settlers arrived during the 1850s, attracted to the fruitful land and an abundance of timber and game. The Dakota War of 1862 left the township isolated for several years. The advent of the railroad in Kandiyohi County in 1869 brought new settlers. Many were of Swedish and Norwegian origin; residents of Scandinavian extraction are yet a majority. In 1870, Leon (Chadwick) Willmar, a Belgian acting as an agent for the European bondholder of the St. Paul and Pacific Railroad, purchased the title to Section 1 of Willmar Township. Willmar was traditional as the county seat in 1871 and was incorporated as a village in 1874 and as a city in 1901.

Willmar was the site of a bank robbery by the Machine Gun Kelly gang on July 15, 1930. They robbed the Bank of Willmar (later Bremer Bank) of about $70,000 (equivalent to $1,135,000 in 2021) and mistreated three people.

The Willmar Memorial Auditorium, designed by architect William Ingemann, was the largest assembly hall within 70 miles later than completed in 1938. It was funded by the city of Willmar and permit and federal governments as a Depression-era works project. It contains several murals by Richard Haines commissioned by the Federal Art Project, and wood paneling in the oak doors by WPA artists. It is on the National Register of Historic Places.