Nanomedicine is a way for the treatment of the several types of cancers. In the present study, gold nanoparticles were green-synthesized using the aqueous extract of Mangifera indica. The chemical characterization was studied different techniques including FT-IR, UV-Vis, SEM and TEM. The anti-human gastric cancer activity of AuNPs@Mangifera indica was evaluated using MTT assay. The nanoparticles were formed in a spherical shape with a size less than 100 nm for the particle size. The treated cells with AuNPs@Mangifera indica were assessed by MTT assay about the cytotoxicity and anti-human gastric cancer properties on normal (HUVEC) and gastric cancer cell lines i.e. GC1415, GC1436, NCI-N87 and MKN45. In the antioxidant test, the IC50 of AuNPs@Mangifera indica and BHT against DPPH free radicals were 55 and 49 µg/mL, respectively. The viability of malignant gastric cell lines reduced dose-dependently in the presence of AuNPs@Mangifera indica. The IC50 of AuNPs@Mangifera indica were 212, 213, 250 and 328 µg/mL against GC1415, GC1436, NCI-N87 and MKN45 cell lines, respectively.