Newfolden is a city in Marshall County, Minnesota, along the Middle River. The population was 368 at the 2010 census. Old Mill State Park is nearby.
According to the United States Census Bureau, the city has a total area of 0.9 square miles (2.3 km²), all of it land.
As of the census of 2000, there were 362 people, 160 households, and 94 families residing in the city. The population density was 404.9 people per square mile (157.0/km²). There were 176 housing units at an average density of 196.8 per square mile (76.4/km²). The racial makeup of the city was 99.17% White, 0.55% African American, 0.28% from other races. Hispanic or Latino of any race were 0.83% of the population.