A visual and quantitative ELISA-like method for Escherichia coli O157:H7 is developed based on highly catalytic and stable Au@AuPt nanoparticles. The proposed enhanced ELISA method can visually detect 100 CFU mL⁻¹ O157:H7 with high specificity and without the need for strict low-temperature reagent storage, thereby increasing the utility. Moreover, it is applicable to spiked tap water and milk tea samples without additional treatments.