In the replacement of petroleum-based non-degradable polymers with natural biopolymers, insufficient physicochemical performance and functionality are representative factors limiting their realization. Herein, an eco-friendly fish gelatin/liquid hydrolysate composite film (FG/H film) with improved physicochemical properties and added functionality was prepared by utilizing liquid hydrolysate derived from Miscanthus. The liquid hydrolysate mainly comprised xylose derived from hemicellulose and extracted lignin and could be widely applied as a solvent and crosslinker and improve the functionalization of the fish gelatin film. The Maillard reaction between the liquid hydrolysate and gelatin decreased the moisture vulnerability and improved the structural stability of the existing gelatin. Compared with pure gelatin, the mechanical properties of the prepared FG/H film were significantly improved, with a tensile strength of 23.76 MPa, a Young’s modulus of 2.38 GPa, and a toughness of 5418 kJ/m³ . In addition, the Maillard reaction product and lignin in the liquid hydrolysate could impart excellent UV-blocking ability of more than 99 % and antioxidant function to the gelatin composite film. Moreover, the manufactured FG/H films exhibited excellent biodegradability. The FG/H films was produced in an eco-friendly manner in all stages, including the use of natural raw materials, the aqueous film manufacturing process, and the imparting of multifunctionality, and is expected to find application in various fields, such as edible packaging films.