Cadherin-17 (CDH17), a structurally unique member of the non-classical cadherin family, is associated with poor survival, cell proliferation, and metastasis in colorectal cancer. However, the role of CDH17 in the apoptosis and autophagy of colorectal cancer cells remains unclear. Here, we aimed to investigate the effect of CDH17 knockdown on autophagy and apoptosis in colorectal cancer cells. We inhibited CDH17 expression in KM12SM and KM12C colorectal cancer cells by RNA interference and found that silencing of CDH17 significantly inhibited cell viability and increased apoptosis in KM12SM and KM12C cells. In addition, silencing of CDH17 significantly increased the expression of cleaved caspase-3 and Bax and decreased the expression of Bcl-2. Concurrently, silencing of CDH17 significantly inhibited the conversion of LC3-I to LC3-II and decreased the formation of LC3⁺ autophagic vacuoles and the accumulation of acidic vesicular organelles, indicating that autophagy was significantly inhibited in KM12SM and KM12C cells. Additionally, treatment with the autophagy-specific activator rapamycin attenuated apoptosis in CDH17-knockdown cells and as indicated by decreased caspase-3 activity, decreased expression of cleaved caspase-3 and Bax, and increased expression of Bcl-2. In conclusion, CDH17 silencing induced apoptosis and inhibited autophagy in KM12SM and KM12C cells, and this autophagy protected the cells from apoptotic cell death.