A moldable ankle flexible brace is disclosed. The flexible ankle brace may include a heat-moldable, multi-layer leg support portion, a heat-moldable, multi-layer foot support portion, a pair of hinges connecting the leg support portion to the foot support portion, an opening for receiving a user's ankle, and a closure mechanism. The flexible ankle brace may include a middle layer that is substantially stiff at a temperature below about 130° F. and moldable at temperatures above 130° F. Also disclosed is a method of using a flexible ankle brace to treat an ankle. The method may include, for example, heating the brace to above 130° F. placing the heated brace on a patient's ankle and molding the brace to conform to the shape of the patient's ankle.