Cellular therapies are a rapidly evolving approach to treat cancer in the light of their unique mechanism of action that potentially overcomes drug resistance and induces durable remissions. Modalities of adoptive cell therapy include gene-modified T cells expressing novel T cell receptors or chimeric antigen receptors (CAR) that modify the immune system to recognize tumor cells and carry out potent anti-tumor effector functions. CAR T cells have shown very promising clinical results and several trials are being conducted worldwide to establish their role in cancer treatment. Most successful results have been observed in lymphoproliferative disorders with the use of CD19-directed CAR T cells, which led to their commercial approval by FDA. In this review, we provide a comprehensive overview of the current role of CAR T cell therapies in hematological malignancies and solid tumors, their associated toxicities and potential future developments in the armamentarium for cancer treatment.