A method of making a lightweight foamed recycled leather is described. The method includes pulverizing the collagen fiber waste generated in a controlling a thickness of the leather during a leather process; neutralizing the resultant of step (a) by a soda ash with a water; (c) dyeing and fat-liquoring process treating the resultant of the step (c); (d) mixing a latex, a dispersant, a coagulant, and a thermally expandable microspheres with the resultant of step (c); (e) coagulating a collagen fiber powder and the latex by adding a coagulant into the resultant of step (d); (f) dehydrating and drying the resultant of step (e); and (g) heat treating the resultant of step (f) to foam thermally expandable microspheres, thereby to impart functionality to the recycled leather.