Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal malignancies worldwide, characterized by late-stage diagnosis, profound chemoresistance, and a five-year survival rate that barely exceeds 12%. The fibrotic stromal barrier surrounding the tumor actively suppresses immune infiltration and blocks drug delivery, rendering conventional treatment options largely ineffective. CRISPR-Cas9-mediated gene knockout represents a promising strategy to overcome this stromal barrier-associated therapeutic resistance by enabling precise disruption of genes that sustain desmoplastic signaling, stromal-immune crosstalk, and drug efflux pathways within the tumor microenvironment. In this context, CRISPR-Cas9-guided gene knockout has opened a new chapter in PDAC research by enabling precise, scalable analysis of the cancer genome. Functional screens using this technology have mapped critical oncogenic dependencies, identifying mutant KRAS, TP53, SMAD4, and CDKN2A as high-value targets, while simultaneously revealing synthetic lethal interactions that were previously inaccessible through pharmacological approaches. These discoveries are now being translated into therapeutic strategies aimed at silencing driver mutations, restoring chemosensitivity, and reprogramming the immunosuppressive tumor microenvironment. Delivery platforms, including lipid nanoparticles, viral vectors, and extracellular vesicles, are being refined to navigate the physical barriers unique to PDAC. Patient-derived organoids and xenograft models are providing the translational framework needed to evaluate these interventions under clinically relevant conditions. This review examines the molecular mechanisms of CRISPR-guided knockout, the genetic vulnerabilities it has uncovered in PDAC, the therapeutic strategies emerging from this work, and the delivery systems supporting clinical translation. The remaining barriers and the steps needed to bring this technology to patients are also discussed.