With the development of many nanomedicines designed for tumor therapy, the diverse abilities of cerium oxide nanoparticles (CONPs) have encouraged researchers to pursue CONPs as a therapeutic agent to treat cancer. Research data have shown CONPs to be toxic to cancer cells, to inhibit invasion, and to sensitize cancer cells to radiation therapy and chemotherapy. CONPs also display minimal toxicity to normal tissues and provide protection from various forms of reactive oxygen species generation. Differential cytotoxicity is important for anticancer drugs to distinguish effectively between tumor cells and normal cells. The antioxidant capabilities of CONPs, which enable cancer therapy protection, have also resulted in the exploration of these particles as a potential anticancer treatment. Taken together, CONPs might be a potential nanomedicine for cancer therapy and this review highlights the current research into CONPs as a novel therapeutic for the treatment of cancer.