Cashews are popular snacks but pose risks to allergic individuals due to Ana o 3 protein. Rapid, accurate detection methods for Ana o 3 are limited. This study developed two detection methods for Ana o 3 allergen. We prepared two monoclonal antibodies, with high specificity and affinity. Using these antibodies, we developed a quantitative sandwich enzyme-linked immunosorbent assay (sELISA) and a qualitative lateral flow immunoassay (LFIA). sELISA's linear range is 0.5-50 ng/mL, with a detection limit of 0.6 ng/mL and a quantification limit of 0.8 ng/mL. Recovery rates in different matrices were 80 %-103 %. LFIA had a visual detection limit of 2.5 ng/mL. In commercial food testing, these methods consistently detected Ana o 3 in products labeled as containing or potentially containing cashews, proving reliable for detecting Ana o 3 allergen and assessing allergen contamination in commercial foods.