Trostianets (; ) is a village in Stryi Raion, Lviv Oblast, in western Ukraine. It is the administrative centre of Trostianets rural hromada, one of the hromadas of Ukraine.
Trostianets is home to the , a natural landmark of Ukraine. The outcrops are home to several fossils from the Tortonian age, lending the landmark its name.
According to the 2001 Ukrainian census, the village had a population of 547. Of this population, all but one citizen spoke Ukrainian natively. The remaining citizen spoke Armenian.