In 1933, the University of Wisconsin-Madison began holding freshman classes in Wausau as part of its Extension services. Classes were held in the old Central School.
In 1934, the Extension contracted with the County Normal School to hold classes there, and a full freshman program was offered that fall.
In 1947, the University of Wisconsin Wausau Center, still taught by Extension faculty and housed in the County Normal School building, began to offer sophomore classes, officially becoming a two-year campus.
In 1954, the Marathon County Board began to explore methods of financing a secure, permanent building to offer a full, two-year, liberal arts curriculum in Wausau.
In 1957, pressed by Marathon County, state law was changed to permit the county to finance construction of a university building.
In 1957, the County Board authorized architectural work on the university building. In February 1958 it allocated $530,000 for the building to be built, and ground was broken in September 1958.
In 1960, Marathon County opened the first new University of Wisconsin Center building in the state. This building is currently part of the administrative and classroom complex on the north end of the main academic building.
On July 1, 1964, the UW Center System was officially created to include all of the two-year centers that were in operation and any future ones. That is when they officially ceased being called Extension Centers.
The County Teachers Colleges were closed by July 1, 1968. The Normal building in Wausau was demolished in November 1968.
In August 1997, the institution officially became the University of Wisconsin-Marathon County (UWMC), part of UW Colleges.
On April 6, 1997, an open house was held to celebrate the renovation of the campus, including building the student union, expanding the library and updating the administrative area and classrooms. Work on this project began in 1995 and was completed in January 1997.
A new Art building was constructed in November 2003, offices and a classroom were added to the Fieldhouse in October 2005, and a renovation of two floors of the South Hall Science Wing were completed in January 2007.
The new $6.8 million UW Center for Civic Engagement building opened on Oct. 23, 2010.
As part of the UW-System restructuring plan approved by the UW Board of Regents, the Wausau campus became a branch campus of UW-Stevens Point on July 1, 2018.