Abstract <p>This study aimed to investigate the preparation of composite films made from cassava starch (CS) of the Khaek Dam cultivar and polyvinyl alcohol (PVA), crosslinked with citric acid (CA) at various concentrations 0, 0.1, 0.3, 0.5, and 0.7% (based on the dry weight of CS). The results showed that film thickness increased with higher CA concentrations. The water activity (<i>a</i>_w) of the films ranged from 0.40 to 0.43. At 0.3% CA, the water solubility, water absorption, and water vapor permeability of the composite film decreased, while puncture strength and tear strength increased. However, at higher CA concentrations (0.5–0.7%), water solubility, water absorption, and vapor permeability increased, while puncture and tear strength decreased. Biodegradability tests showed that the composite films degraded by 36.84 to 53.39% for 8 weeks. When used as banana packaging, the composite film containing 0.3% CA demonstrated the highest efficiency in extending shelf life, maintaining freshness for nearly 7 days longer compared to bananas not sealed with the composite film. These findings suggest that the composite film made from CS and PVA, crosslinked with 0.3% CA, offers the most favorable overall properties-both in terms of physical and mechanical properties as well as fruit preservation potential. This highlights its promise for future development as a biodegradable polymer film for food packaging applications.</p>