Beinwil am See (in native dialect: Böiu, [b̥œi̯ʊ]) is a municipality in the district of Kulm in the canton of Aargau in Switzerland. It is located in the Seetal on the western shore of Lake Hallwil and borders the canton of Lucerne. Until 1950 was the official name of the municipality Beinwil (district Kulm).