Castiadas is a comune located in the Metropolitan City of Cagliari within the Italian region of Sardinia. It is situated approximately 35 kilometres (22 mi) east of the city of Cagliari and is part of the Sarrabus-Gerrei historical region.
The municipality was founded during the 14th century. Following a period of abandonment that lasted for centuries, it was subsequently repopulated in the 19th century.