An embodiment armrest assembly for a vehicle includes an armrest including a main body and a lid, an armrest board to which the armrest is rotatably coupled and in which the armrest is accommodated in an erect state, and a skirt coupled to a rear bezel housing of the lid and to the armrest board and correspondingly covering a rear space of the lid when the armrest is rotated forward, wherein the skirt has a panel shape and includes a hard material.