Background: Periodontal disease (PD) and polycystic ovary syndrome (PCOS) are two prevalent conditions that have been independently associated with systemic inflammation and hormonal dysregulation. Emerging evidence suggests a potential bidirectional relationship between these conditions, but the nature and strength of this association remain unclear. Objective: This systematic review aimed to evaluate and synthesize the existing evidence on the association between periodontal disease and polycystic ovary syndrome, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Methods: A comprehensive literature search was conducted in multiple databases, including PubMed, Scopus, and Web of Science, from 1990 to 2025. Studies investigating the association between PD and PCOS in terms of prevalence, severity, and shared pathophysiological mechanisms were included. Two independent reviewers screened studies for eligibility, extracted data, and assessed methodological quality using validated tools. Discrepancies were resolved through consensus. Meta-analysis was conducted where appropriate. Results: A total of nine studies were included. Most studies reported a higher prevalence and severity of periodontal disease among women with PCOS compared to controls. Shared mechanisms, including systemic inflammation, insulin resistance, and hormonal dysregulation, were frequently proposed as underlying factors. However, heterogeneity in study designs, diagnostic criteria, and confounding adjustments limited the comparability of findings. Conclusions: This systematic review supports a potential association between periodontal disease and polycystic ovary syndrome, likely mediated by common inflammatory and metabolic pathways. However, the evidence is limited by heterogeneity and methodological biases. Further well-designed longitudinal studies are needed to clarify causal relationships and explore the clinical implications of integrating periodontal health management into PCOS care.