Immuno-oncology represents an emerging field that has significantly transformed tumor therapeutics, with immune cells serving as the cellular foundations of cancer immunotherapy. Due to its high efficiency and sensitivity, CRISPR/Cas9 genome editing is a highly promising technique for precise and rapid gene modification. This review provides an overview of recent advancements in the application of CRISPR/Cas9-edited tumor-associated immune cells in cancer therapy, including T lymphoid cells, natural killer (NK) cells, macrophages, and B lymphoid cells et al., exhibiting a potential impact on the pathological status of cancer. Moreover, various editing strategies have been implemented to target tumor-associated immune cells in tumor microenvironment. These strategies include the knockout of inhibitory signals, endogenous T cell receptor genes, transcription factors and post-transcriptional regulatory factors, as well as the introduction of chimeric antigen receptors into T cells, macrophages, and NK cells. Additionally, efforts have been made to reprogram the phenotypes of macrophages. This review also addresses the current challenges associated with the application of CRISPR/Cas9 technology to tumor-associated immune cells and explores the potential future clinical applications of these advancements. reprogramming the phenotype of the macrophage.