Tumor treatment has entered a new phase because to cancer immunotherapy in recent years. For a variety of human diseases, researchers have been looking for ways to alter the immune system at different phases of treatment. Chimeric Antigen Receptor (CAR) therapy is a quickly developing cancer treatment that is a subset of adoptive cell treatments (ACT). By injecting CAR molecules into immune cells, this method genetically alters them, giving them new skills to identify cancer cells and reroute malignant tumor cells through specific actions. As a result, refractory cancers have shown significant responses. As the first line of defense against infections and malignant cells, CAR Natural Killer (NK) cells are a combination of CAR molecules and innate immune cells, more especially NK cells, which are an essential part of the innate immune system. The potential for using CAR-NK cells to treat a variety of malignant tumors has been greatly increased by their ability to target a wide range of tumor antigens via particular signaling pathways on the surface of NK cells. The targeting accuracy and cytolytic activity of NK cells against tumor cells have significantly increased due to the integration of CAR molecules that target tumor-specific antigens, increased immune cell activity, and the innate anti-tumor capabilities of NK cells. Compared to CAR-T cells, CAR-engineered NK cells have a wider choice of sources during production, may produce a variety of inflammatory cytokines, facilitate cytotoxic effects, and have less side effects after treatment. Many researchers are interested in studying and exploring NK cells through various clinical studies because of these benefits, which position them as a prospective platform for CAR-based therapy. The possibilities and difficulties of using CAR NK cells to treat cancer are clarified by this review.