The CRISPR/Cas9 gene editing system, derived from prokaryotic adaptive defense mechanisms, has revolutionized various fields by enabling precise gene editing. Its impact has been particularly significant in cancer research, facilitating improved disease modeling, identification of new cancer-related genes, and more accurate diagnosis, especially for challenging subtypes like triple-negative breast cancer (TNBC). TNBC's resistance to targeted therapies due to the absence of hormone receptors underscores the importance of CRISPR technology. Utilizing guide RNA to direct Cas9 enzyme to specific genomic loci, the CRISPR system induces double-strand breaks, which are repaired by endogenous DNA repair mechanisms, enabling gene insertions, deletions, or modifications. The CRISPR process involves three key steps: guide RNA design and complex formation with Cas9, DNA cleavage at the target site, and cellular repair through non-homologous end joining or homology-directed repair pathways. With its versatility and precision, CRISPR/Cas9 emerges as a potent tool driving innovative cancer research and therapeutic development.