It issues from Lake Osakis on the Todd County line and flows east through Guernsey Lake, Little Sauk Lake and Juergens Lake, then south through Saulk Lake and past Sauk Centre, southeast past Melrose and Richmond, then northeast through Cedar Island Lake and Zumwalde Lake, past Cold Spring and Waite Park to the Mississippi River 2 mi (3.2 km) north of St. Cloud.
The river is popular with canoers.
The rapids that occur south of the river's mouth on the Mississippi River lent their name to the nearby city of Sauk Rapids.
In 1847, the Mississippi Chippewa ceded their lands about the Sauk River to the United States for the purpose of establishing a homeland for the Winnebagoes, who at the time were being removed out of Wisconsin. However, due to continued skirmishes between the Ojibwe and the Dakota, the Winnebagoes were placed in constant danger. By their request, the United States relocated the Winnebagoes to south-central Minnesota, then to South Dakota and finally in Nebraska. Some of the Winnebagoes, however, returned to Wisconsin despite their removal.