The persistent global issues of unsafe food and food waste continue to exist. Microbial contamination stands out as a major cause of losses in perishable foods like vegetables and fruits. Herein, we report a self-assembling coating based on disulfide bond cleavage-induced bovine serum albumin (BSA), where the antimicrobial activity of chitosan oligosaccharide (COS) is stably anchored in the coating by electrostatic interactions during the unfolding-aggregation phase of BSA. The intrinsic antimicrobial activity of COS, combined with the positively charged and hydrophobic regions enriched on the BSA coating, significantly disrupts the integrity of bacterial structures. Furthermore, the BSA@COS coating can easily adhere in situ to the grooves on the surface of strawberries through a simple one-step spraying process, extending the shelf life of strawberries and bananas by nearly three times. This makes it a potential economic alternative to current commercial antimicrobial coatings, offering a solution to the rampant global issue of food waste. Display omitted •Disulfide bond breaking induces hydrophobic self-assembly of BSA into protein coatings•Chitosan oligosaccharide COS is stably bound to the BSA coating through electrostatic interactions•BSA@COS coating can be easily adhered to fruit surfaces by one-step spray application