Cell therapy has emerged as a groundbreaking approach capitalizing on the unique properties of living cells to mount a targeted assault on cancer cells. This chapter delves into the exciting field of cell therapy, exploring its principles, mechanisms, and clinical applications in cancer treatment. We discuss the various types of cells used in cancer therapy, including T cells, natural killer cells, dendritic cells, and examine the latest advances in cell-based immunotherapies, such as CAR-T cell therapy and adoptive T cell transfer. The chapter also addresses the challenges and limitations of cell therapy, including tumor heterogeneity, immune evasion, and toxicity. Furthermore, we explore the future directions of cell therapy research, including combination therapies, personalized approaches, and innovative technologies to enhance efficacy and safety. By providing a comprehensive overview of cell therapy in cancer, this chapter aims to highlight its transformative potential in cancer care.