The use of the body’s own defenses to combat cancer represents a cornerstone of cancer immunotherapy. Enhancing the innate functionality of the immune system enhances its ability to identify and eradicate cancerous cells within the body. Among the array of cancer immunotherapy approaches, chimeric antigen receptor (CAR)-natural killer (NK) cell therapy has emerged as a promising contender. CARs, engineered synthetic receptors, redirect NK cells to identify and eliminate cells expressing specific antigens. NK cells, which are integral to the innate immune response, exhibit rapid and potent cytotoxicity against cancer cells without requiring prior sensitization or peptide antigen recognition. Activated NK cells execute targeted cell death through perforin and granzyme release, alongside the secretion of proinflammatory cytokines such as interferon-gamma (IFN-gamma) and tumor necrosis factor (TNF-alpha). Unlike T cells, NK cells possess inherent cytotoxicity, offering advantages in cancer immunotherapy. When equipped with CARs, NK cells synergistically target and destroy transformed cells. The robust antitumor activity and favorable safety profile of these compounds have spurred significant interest in CAR-NK-cell immunotherapy. To overcome limitations associated with autologous NK cells, including reduced efficacy and patient-specific production requirements, allogeneic NK cells have emerged as promising platforms for CAR engineering. NK cells have demonstrated efficacy against certain hematological cancers and show promise in preventing metastasis, as evidenced by animal studies and clinical observations. Preclinical investigations highlight the ability of NK cells to target and eliminate host lymphohematopoietic cells involved in donor cell rejection. Overall, advancements in CAR-NK cell technology offer valuable insights into the intricacies of cancer immunotherapy and hold promise for further therapeutic development.