Breadfruit is widely cultivated and used as a traditional medical for treating various diseases. From the ethyl acetate extract of breadfruit leaf, three geranyl flavonoid were isolated comprising 2-geranyl-3,4,2’,4¢-tetrahydroxydihydrochalcone AA1, 1-(2,4-dihydroxyphenyl)-3-[8-hydroxy-2-methyl-2-(4-methyl-3-pentenyl)-2H-1-benzopyran-5-yl]-1-propanone AA2 and (S)-Sophoraflavanone A AA3. The biosynthesized pathway of these isolated compounds were proposed through the key step condensation between geranyl pyrophosphate and flavonoid moiety. The in vitro antioxidant activities revealed both methanol and ethyl acetate extract possessed antioxidant effect and the ethyl acetate extract was the most effective with IC₅₀ value 79.3 and 9.32 mg/mL in comparison to positive control, Vitamin C with IC₅₀ value 4.39 and Trolox 11.80 mg/mL in both DPPH and ABTS methods, respectively.