Cancer is defined as the outrageous growth of cells in a part of the body. It is one of the most common causes of death and its burden is on the rise all over the world. Breast cancer is the most common cause of death among all cancer types. Traditional cancer treatments are surgery, radiation therapy, and chemotherapy. Cancer immunotherapy is another new approach to the treatment of cancer, which in general means the potentiation of the immune system against cancer. It is mostly categorized into two subgroups: passive and active immunotherapy. There are some mechanisms developed as cancer immunotherapy consisting of monoclonal antibodies (mAbs), cytokines, cancer vaccines, natural killer (NK) cell therapy, immune checkpoint blockade, chimeric antigen receptor T (CAR-T) cell therapy, and oncolytic virotherapy. In this chapter, we are going to discuss the efficacy of these treatments alone or in combination with other modalities and the current development in different cancers, including breast cancer, urologic cancers, gastrointestinal cancers, pediatric cancers, skin cancers, endocrine cancers, and lung cancer.