In winemaking, large amounts of grape skin (GS) are produced as by-products, which contain not only abundant degradable cellulose, hemicellulose, and pectin but various functional polyphenols. In contrast to most studies focusing on the utilization of extractives, the current study investigates the use of an ultrasonicated grape skin (UGS) containing all components to develop a multifunctional composite lm.Owing to dissociation during ultrasonication, all GS components were well dispersed in water to obtain the UGS suspension. Transmission electron microscopy (TEM) indicated that the celluloses were successfully transformed into cellulose nano bers (CNFs), which can improve the uniformity of the composite lm. Subsequently, biodegradable and multifunctional composite lms were fabricated by combining the UGS and polyvinyl alcohol (PVA). The UGS and PVA formed a good interface owing to strong hydrogen bonds, and the resulting lms exhibited excellent thermal stability and moisture-sensitive mechanical properties. The polyphenols in the UGS suspension endowed the composite lm with multiple functions, including pH-responsive color change, excellent antioxidant activity, ultraviolet shielding, and antimicrobial properties. The use of PVA enhanced the exibility, strength, and elongation of the UGS lm.The easily prepared, tailored, multifunctional, and biodegradable UGS/PVA composite lm exhibits excellent potential for application in agriculture, cosmetics, and healthcare.