A vehicle door handle assembly may include a handle housing disposed inside a door panel; a slider slidably mounted in the handle housing to be movable between a first position and a second position of the handle housing; a handle member pivotally connected to the slider through a connecting arm, and configured of being movable between a rest position and an actuating position with respect to the door panel; and an inertia locking mechanism including a blocking lever pivotally mounted to the handle housing, and a weight mounted on the blocking lever, wherein the inertia locking mechanism may prevent the handle member from moving to the actuating position by an unwanted force caused by the collision/impact of the vehicle.