Sweet Grass Creek is a tributary of the Yellowstone River, approximately 50 mi (80 km) long, in south central Montana in the United States.

It rises in the Gallatin National Forest , in the Crazy Mountains in eastern Park County. It flows northeast, into Sweet Grass County, then southeast, past Melville , and south, joining the Yellowstone 2 mi (3 km) northwest of Greycliff.

See List of Montana rivers