Due to the risks they pose to human and environmental health, there has been a strong push in recent times to reduce the use of chemical fungicides in phytopathogen treatment. In the present study, vicilin was isolated from kidney bean seeds and characterized by SDS-PAGE, zeta potential, and pH solubility curve. The α/ (85 KDa), α (70 KDa), and β (60 KDa) subunits were represented by three distinct protein bands in vicilin. The linear growth of B. cinerea was clearly reduced by 12.96%, 14.81%, 25.92%, 35.18%, and 40.73% in response to vicilin application at 50, 100, 200, 300, and 400 µg/ml, respectively. The scanning electron microscopy (SEM) of vicilin-exposed B. cinerea revealed hyphae enlargement and conidia distortion. Addition of vicilin from kidney bean seeds clearly reduced the disease incidence in a concentration-dependent manner (100, 200, and 400 µg/mL). The higher doses (400 µg/mL) of vicilin provided higher activity in decreasing the disease severity of the strawberry fruits. As a sustainable glycoprotein, vicilin, found in kidney bean seeds, can be used to combat postharvest fungal infections.