<p>Polychlorinated biphenyls (PCBs), as persistent organic pollutants, are known for their long-term environmental persistence and potential adverse health effects, including cancer. This systematic review and meta-analysis investigate the association between PCBs exposure and stomach cancer mortality. A comprehensive search of databases, including Scopus, PubMed/MEDLINE, and Web of Science until October 15, 2024, identified 1250 studies six of which met inclusion criteria. Pooled results from the meta-analysis reveal sex-specific differences in the risk of cancer mortality associated with PCB exposure. Among females, the pooled standardized mortality ratio (SMR) was 0.77 (95% CI 0.46–1.07), indicating a lower risk of cancer mortality, while males had a pooled SMR of 1.29 (95% CI 0.98–1.60), showing an increased risk with low heterogeneity for both subgroup analyses. The overall pooled SMR for both sexes was 1.06 (95% CI 0.77–1.36), indicating no significant association when combining both sexes. Moderate heterogeneity was observed in the overall analysis (<i>I</i>² = 35.85%, <i>p</i> = 0.15), and the test for group differences revealed significant variation in the effects of PCB exposure on cancer mortality between males and females (Qb = 5.62, <i>p</i> = 0.02). The funnel plot and Egger’s test indicated little to no publication bias, while the Galbraith plot showed no significant outliers, suggesting low heterogeneity and consistency with the pooled estimate. In addition, the sensitivity analysis demonstrated that the overall effect size remained stable across iterations, confirming the robustness and reliability of the meta-analysis results. These findings underscore the importance of considering sex differences when evaluating the health effects of PCB exposure.</p>