A chair convertible into a chaise lounge comprises: a stationary base structure having a front section and a rear section, a sitting unit including a seat portion and a backrest portion, wherein the seat portion is inclined with respect to a horizontal plane; and two foot-rests, each of which has a portion for resting the feet and a portion for resting on the floor. Each of the foot-rests is articulated to the front section of the base structure about a respective vertical axis of articulation and is rotatable substantially through 180° between an inoperative position and an operative position. In the inoperative position, each portion for resting the feet extends underneath the seat portion of the sitting unit, and in the operative position each portion for resting the feet extends forward beyond a front edge of the seat portion and has an inclination with respect to a horizontal plane opposite with respect to the inclination of the seat portion.