During the last three decades, there has been substantial advancement in comprehending the chemical attributes and roles of natural killer (NK) cells, resulting in a growing interest in these cells. Simultaneously, the swift advancement of adoptive transfer therapy for immune cells, particularly the impressive achievements of autologous chimeric antigen receptor-T (CAR-T) cells in treating hematological malignant tumors, has fueled interest in using immune cells as a cancer treatment modality and opened the door for NK cell adoptive immunotherapy. NK cell-mediated immunotherapy has shown potential as a readily available, safe, and effective treatment for patients with leukemia. Moreover, clinical studies have demonstrated that NK cell adoptive immunotherapy shows efficacy in various solid tumors and hematologic malignancies, indicating a promising future for this therapeutic approach. This paper will provide an overview of NK cell adoptive therapy, focusing on current clinical trial results and the challenges associated with clinical applications.