The town in the middle of Le Sueur County was designated its county seat in 1876 and eventually named Le Center. Area Catholics attended Mass at St. Henry, a Romansch language parish three miles to the west, but the many Irish settlers wanted Mass in their own language in their growing hometown. St. Mary was established in 1899, first Mass was celebrated in the local public school June 5, a wood frame church was completed December 12, and the first pastor took residence in the rectory by Christmas.             

A parochial school was added in 1915, staffed by Sisters of St. Joseph, operating until its closure in 1971. In 1958, the original church was replaced by a larger building featuring a Mankato limestone façade and vibrant stained glass windows and it included a social hall. A new parish rectory was built in 1978, and a new office complex was completed in 2002. The parish is now linked with three others—St. Henry, Nativity in Cleveland, and Immaculate Conception in Marysburg— sharing clergy, office staff, and dedicated volunteers. A growing Latino population in the area is served by Mass in Spanish and is breathing new life into the community.