The Platte flows from Platte Lake in southeastern Crow Wing County, flows through Lake Sullivan, and Round Lake, and follows a generally southwestward course through eastern Morrison County, through the towns of Harding and Royalton. It flows into the Mississippi River in Benton County, about 3 miles (5 km) south of Royalton.
The Platte's largest tributary is the Skunk River, which joins it in Morrison County.