Mango (Mangifera indica) has been one of the most cultivated fruits in Thailand and other South and Southeast Asian countries. ‘Bao’ mango is a distinct petite mango variety that is available all year round. This study aimed to investigate the antioxidant and anti‐breast cancer activities of Bao‐mango peel extract (MPE). The total phenolic content (TPC) of MPE was 280.57 ± 7.95 mg quercetin per g of powder. Based on antioxidant activity analyses, MPE had IC50 values of 35.09 and 23.80 ± 0.48 mg/mL for 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and 2,2′‐azino‐bis‐3‐ethylbenzthiazoline‐6‐sulphonic acid (ABTS) radical scavenging activities, respectively. Additionally, MPE exerted an inhibitory action against MDA‐MB‐231 breast cancer cells with an IC50 of 39.08 ± 5.22 mg/mL. Furthermore, nanoencapsules loaded with MPE using chitosan‐coated poly lactic‐co‐glycolic acid (CS‐PLGA‐(MPE)) were also prepared. It exhibited spherical morphology with an average size of 251.90 ± 19.61 nm. Encapsulation efficiency (EE) of nanoparticles was 30.48%. Moreover, the CS‐PLGA‐(MPE) exhibited higher anticancer activity by affecting cell viability and inhibiting the cell migration and invasion of MDA‐MB‐231 breast cancer cells, compared to the free MPE. Therefore, these findings indicated that MPE and CS‐PLGA‐(MPE) nanoparticles could be promising alternatives to chemicals used for breast cancer treatment.