Marshfield is a city in Wood and Marathon counties in the U.S. state of Wisconsin. The population was 18,929 at the 2020 census; of this, 18,119 were in Wood County and 810 were in Marathon County. It is a principal city of the Marshfield–Wisconsin Rapids micropolitan statistical area, which includes all of Wood County and had a population of 74,207 in 2020.

It is located at the intersection of U.S. Highway 10, Highway 13 and Highway 97. Marshfield is home to the Marshfield Clinic, a large healthcare system that serves much of Central, Northern, and Western Wisconsin.