The mortality rate of cancer is ranked second worldwide. The most common treatment options for cancer patients are radiation, chemotherapy, and/or surgery. When these standard therapies are combined on the primary tumor, they are most often effective, but preventing disseminated tumor cells from spreading is usually more challenging. By using cancer immunotherapy, cancer cells disseminated throughout the blood circulation, as well as micro-metastases in distant organs, can be treated. In cancer immunotherapy, antibodies target specific cancers and immune effector mechanisms. Cancer immunotherapy, including its mechanisms, therapeutic agents, and clinical implications, is discussed in this chapter. The challenges associated with next-generation CAR-Ms and personalized vaccines are also discussed. Combining immunotherapy and chemotherapy, radiotherapy, or epigenetic modulators can maximize treatment effectiveness. In conclusion, individualized medicine approaches and ongoing research will impact cancer immunotherapy in the future.