This study aimed to prepare Annona squamosa leaf extract-loaded chitosan nanoparticles (nano-ASLE) against human colon cancer (WiDr) cells. Nano-ASLE was made with ionic gelation method. Four concentrations of the nano-ASLE (50, 100, 200, and 400 μg/mL) in dimethyl sulfoxide were prepared on WiDr cells to determine the IC50 value using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Then, it was divided into three groups of concentration of IC50, 2IC50, and 4IC50 and continued with analysis of caspase-3 expression and cell cycle arrest. The results of particles size were obtained 535.1 nm and showed potent cytotoxicity with IC50 292.39 μg/mL. The expression of caspase-3 increased significantly and caused cell cycle arrest at the G2/M phase and induced apoptosis on WiDr cells. Further studies are needed to obtain the loading efficiency, release of drug concentration, and in vivo study of nano-ASLE to suppress WiDr cells.