Natural killer (NK) cells, a subset of innate lymphocytes, rapidly activate multiple signaling pathways without prior sensitization to directly eliminate virus-infected cells or tumor cells. Due to the limitations of T lymphocytes and the unique traits of NK cells, NK cell-based immunotherapies reveal multifaceted advantages over T cell-based ones to some extent. However, they still have certain limitations, such as NK cell silence in tumor microenvironment (TME), limited therapeutic effect, and high treatment costs. Nanomaterials are materials with a diameter ranging from 1 nm to 100 nm. By precisely manipulating the physical and chemical properties (e.g, shape, size, hydrophobicity, and surface modifications), nanomaterials can be engineered to achieve targeted delivery of therapeutic agents (e.g., drugs, cytokines, and RNAs). This capability enables precise manipulation of the microenvironment in target tissues or specific modulation of cellular behaviors, thereby enhancing the efficacy of immunotherapy strategies. The state-of-the-art progress in nanoparticles has supplied new applications for NK cell-based immunotherapies. Herein, we outline the immunotherapy of NK cells, nanotechnology that enhances immunotherapy, and recent advances in nanoparticles for facilitating the targeted therapy by NK cells.