Wasilla is a city in Matanuska-Susitna Borough, United States and the fourth-largest city in Alaska. It is located on the northern point of Cook Inlet in the Matanuska-Susitna Valley of the southcentral part of the state. The city's population was 5,469 at the 2000 census; the Census Bureau estimated that it had risen to 10,256 in 2008.

Wasilla is the largest city in the borough and a part of the Anchorage metropolitan area, which had an estimated population of 364,701 in 2008. Established at the intersection of the Alaska Railroad and Old Carle Wagon Road, the city prospered at the expense of the nearby mining town of Knik. Historically entrepreneurial, the economic base shifted in the 1970s from small-scale agriculture and recreation to support for workers employed in Anchorage or on Alaska's North Slope oilfields and related infrastructure.