AbstractThe research aimed to prepare eco‐friendly bio‐nanocomposite films utilizing gelatin/starch (GS), nano‐ZnO, and Darbha grass extract via the solution casting method. Then, it was examined the mechanical and physical properties of different durations of sunlight exposure on the prepared films. The results indicated that up to 12 h of sunlight exposure led to increased film thickness, mechanical strength, and apparent density. Tensile strength increased from 4.8 to 34.8 MPa, and the average crystalline size of the nanoparticles was found to be 54.35 nm using scanning electron microscope. Compared with GS films, these bio‐nanocomposite films exhibited lower moisture content, oil permeability, and enhanced water barrier properties. Moreover, they displayed significant UV absorption and profound antimicrobial activity against both gram‐positive and gram‐negative food borne pathogenic bacteria. The nano‐ZnO/Darbha grass extract‐based bio‐nanocomposite films exhibited showed improved characteristics and could be applied in the field of food packaging application.