This study investigates the synergistic effects of ultrasound (US) and slightly acidic electrolyzed water (SAEW) on the postharvest quality of grapes. The research compares this combined treatment with conventional water cleaning (CW), exclusive US treatment, and standalone SAEW treatment. The results show that the US + SAEW treatment significantly reduces microbial counts, with reductions of 2.23 log CFU/g and 2.76 log CFU/g for total bacteria and mold & yeast, respectively. This treatment also minimizes weight loss, color deviations, polyphenol oxidase activity, and malondialdehyde synthesis, while preserving firmness, sugar-acid ratio, and key enzyme activities. Consequently, the US + SAEW treatment delays the onset of decay by 12 days compared to other treatments. The mechanism behind this superior performance is attributed to the ultrasound-induced removal of the wax layer on grape skins, which transitions the skin from hydrophobic to hydrophilic, increasing the contact area between the grape surface and SAEW and enhancing its antimicrobial efficacy. These findings highlight the potential of US + SAEW as an effective strategy for maintaining grape quality during postharvest storage.This study investigates the synergistic effects of ultrasound (US) and slightly acidic electrolyzed water (SAEW) on the postharvest quality of grapes. The research compares this combined treatment with conventional water cleaning (CW), exclusive US treatment, and standalone SAEW treatment. The results show that the US + SAEW treatment significantly reduces microbial counts, with reductions of 2.23 log CFU/g and 2.76 log CFU/g for total bacteria and mold & yeast, respectively. This treatment also minimizes weight loss, color deviations, polyphenol oxidase activity, and malondialdehyde synthesis, while preserving firmness, sugar-acid ratio, and key enzyme activities. Consequently, the US + SAEW treatment delays the onset of decay by 12 days compared to other treatments. The mechanism behind this superior performance is attributed to the ultrasound-induced removal of the wax layer on grape skins, which transitions the skin from hydrophobic to hydrophilic, increasing the contact area between the grape surface and SAEW and enhancing its antimicrobial efficacy. These findings highlight the potential of US + SAEW as an effective strategy for maintaining grape quality during postharvest storage.