Willamina is a city in Polk and Yamhill Counties in the U.S. state of Oregon. The population was 1,844 at the 2000 census, with an unofficial estimated population of 1,885 in 2006. The Yamhill County portion of Willamina is part of the Portland–Vancouver–Beaverton, OR-WA Metropolitan Statistical Area, while the Polk County portion is part of the Salem, OR Metropolitan Statistical Area.