Köyliö (Swedish:Kjulo) is a former municipality of Finland. It was merged to the municipality of Säkylä on 1 January 2016.
It was located in the province of Western Finland and was part of the Satakunta region. The population of Köyliö was 2,665 (30 June 2015) and covered a land area of 246.06km (95.00sqmi). The population density was 10.8307/km (28.051/sqmi).