The increasing prevalence of overweight/obesity among the elderly has significant implications for oral health due to shared pathophysiological mechanisms. Despite its importance, comprehensive reviews on this topic remain limited. This study investigates the association between overweight/obesity and oral health outcomes in adults aged 55 and older. This systematic review followed PRISMA guidelines and was registered with PROSPERO (CRD42020202108). A systematic literature search was conducted across PubMed, Embase.com, CINAHL, and Web of Science up to November 6, 2023. The study was structured using the Population, Intervention/Exposure, Comparison, Outcome, and Study Design (PICOS) criteria: Population (P) included adults aged ≥ 55 years; Intervention/Exposure (I/E) involved overweight/obesity; Comparison (C) included normal-weight individuals; Outcomes (O) focused on periodontal diseases, dental caries, tooth wear, and orofacial pain; and Study design (S) included case-control, cross-sectional, prospective, and retrospective cohort studies and randomized controlled trials. Eligible studies underwent data extraction and quality assessment using the Newcastle-Ottawa scale. Meta-analyses were conducted using fixed and random effects models in Stata v.18. From 6219 records, 16 studies met the inclusion criteria. Among these, 14 focused on periodontal diseases, while 2 examined dental caries. No studies met the eligibility criteria for tooth wear or orofacial pain. The included studies were predominantly of "good" or "very good" quality. Meta-analysis indicated that overweight or obese older adults had a significantly higher risk of periodontal disease compared with normal-weight counterparts (pooled odds ratio [OR] = 1.49; 95% confidence interval [CI] 1.13-1.97). The association was stronger in studies conducted in Asia (OR = 2.21; 95% CI 1.28-3.81) and in mixed-sex populations (OR = 1.52; 95% CI 1.02-2.28) compared with male-only samples. The two cross-sectional studies on dental caries yielded inconsistent findings, precluding a meta-analysis for this outcome. This systematic review demonstrates a significant association between overweight/obesity and increased prevalence of periodontal disease in adults aged 55 and older. These findings underscore the need to consider oral health as a key component of general health in this population. The current evidence base is insufficient regarding dental caries, tooth wear, and orofacial pain, highlighting the need for high-quality research in these domains.