Port Alsworth is a census-designated place in Lake and Peninsula Borough, Alaska, United States. It is 165 miles by air southwest of Anchorage. Its population was 186 at the 2020 census, up from 159 in 2010. It is the most populated community in the borough. Port Alsworth was founded in 1950 by Babe Alsworth, a missionary and bush pilot, and Mary Alsworth, who was the town's first postmaster.