Large amounts of chromium‐containing leather solid waste (CLSW) generated in conventional leather making industry. The high value‐added transformation of CLSW has attracted lots of attention from scientists and technologists. Herein, gelatin was extracted from CLSW through alkaline hydrolysis dechroming and decalcification process. Then, form‐stable phase change material composites (GMPCMs) based on gelatin, n‐docosane, and melanin were designed and fabricated through impregnating n‐docosane into gelatin/melanin hybrid aerogels (GMAs). The three‐dimensional (3D) honeycombed aerogels GMAs with ultralow density and extremely high surface area can perfectly support n‐docosane and prevent liquid leakage. As expected, the solar‐thermal conversion efficiency of GMPCMs (up to 84.8%) was significantly increased with the introduction of melanin in PCM composites. DSC analysis indicated that GMPCMs possessed relatively large thermal energy storage density and the melting enthalpy of GMPCMs ranged from 207.1 to 228.0 J/g. Furthermore, GMPCMs showed admirable shape stability, excellent encapsulation capacity, and satisfactory thermal reversibility.