Natural killer (NK) cells are a subset of cytotoxic lymphocytes within the innate immune system. While they are naturally cytotoxic, genetic modifications can enhance their tumor-targeting capability, cytotoxicity, persistence, tumor infiltration, and prevent exhaustion. These improvements hold the potential to make NK-cell-based immunotherapies more effective in clinical applications. Currently, several viral and non-viral technologies are used to genetically modify NK cells. For nucleic acid delivery, non-viral methods such as electroporation, lipid nanoparticles, lipofection, and DNA transposons have gained popularity in recent years. On the other hand, viral methods including lentivirus, gamma retrovirus, and adeno-associated virus, remain widely used for gene delivery. Furthermore, gene editing techniques such as clustered regularly interspaced short-palindromic repeats-based, zinc finger nucleases, and transcription activator-like effector nucleases are the pivotal methodologies in this field. This review aims to provide a comprehensive overview of chimeric antigen receptor (CAR) arming strategies and discuss key gene editing techniques. These approaches collectively aim to enhance NK cell/NK cell CAR-based immunotherapies for clinical translation.