ABSTRACTThe aim of this study is to develop a self‐assembled β‐lactoglobulin nanofibril (β‐lg Nfs)‐incorporated carboxymethyl cellulose/carrageenan (CMC/CG) composite edible film using the solution casting method. The structure and physical interactions of β‐lg Nfs within the polymer matrix are evaluated based on their physical, mechanical, barrier, structural, and antimicrobial properties. The results indicate that the incorporation of β‐lg Nfs significantly (p ≤ 0.05) increases the thickness, hydrophobicity (contact angle), tensile strength, and elongation at break while decreasing moisture content, solubility, water vapor transmission rate, and oxygen and carbon dioxide transmission. The morphology of β‐lg Nfs confirms the formation of well‐defined nanofibrils, and the morphology of the edible film confirms a homogeneous structure of CMC/CG edible films, with citric acid acting as a crosslinking agent and the successful incorporation of β‐lg Nfs into the CMC/CG film matrix. FT‐IR studies confirm the chemical interactions within the film matrix with Nfs. Antimicrobial studies reveal that the CMC/CG‐based films show greater activity against E. coli and Staphylococcus aureus . Thus, this research demonstrates that the incorporation of self‐assembled protein nanofibrils into edible films enhances their mechanical, barrier, and water resistance properties, along with their structural integrity, making the film suitable for food packaging applications.