Grasslands National Park, National park in southern Saskatchewan, Canada.

Grasslands National Park is a national park in southern Saskatchewan made of two separate parcels, the West Block and the East Block. The West Block is cut by the Frenchman River valley; the East Block holds the Rock Creek badlands and the Wood Mountain Hills. The land is dry mixed-grass prairie of pale tan and grey grass, with flat terraces and rounded hills.

The area became a national park to protect the last remaining stretches of North American native prairie ecosystems. Before that, intensive farming had turned most of these grasslands into cultivated fields.

The park lies on Treaty 4 land of the Blackfoot (Niitsítapi) people. In 1877, after the Battle of Little Bighorn, Sitting Bull took refuge here with around 5,000 Sioux. A 2022 agreement between the Métis Nation—Saskatchewan and Parks Canada provided for the transfer of 24 bison.

The park has two separate blocks: the West Block is reached from Val Marie via Highway 4, the East Block from Killdeer via Highway 2. The main visitor reception centre is in Val Marie, while the East Block's interpretive centre is in the McGowan House at Rock Creek Campground. A one-lane, 11-kilometre parkway crosses the Rock Creek Badlands. The West Block lies an hour south of Swift Current, the East Block about an hour south of Assiniboia.

The dark sky preserve status allows observation of constellations and the Milky Way without interference from artificial light sources. Visitors can see thousands of stars on clear nights that remain invisible in urban areas.