克瓦西利夫是乌克兰的城镇，位于该国西北部罗夫诺州，始建于1445年，面积4.46平方公里，海拔高度190米，2011年人口8,117，人口密度每平方公里1,820人。

Kvasyliv (Ukrainian:Квасилів; Polish:Kwasiłów) is an urban-type settlement in the Rivne Raion (district) of Rivne Oblast (province) in western Ukraine. Its population is 8,117 as of the 2011 Ukrainian Census. Kvasyliv was first founded in 1445, and it acquired the status of an urban-type settlement in 1959.