Objectives <p><i>Helicobacter pylori</i> (<i>H. pylori</i>) is a prevalent gastric bacterium increasingly detected in the oral cavity and may contribute to the progression of oral diseases. This study aimed to assess the association between oral diseases and oral <i>H. pylori</i> infection.</p> Materials and methods <p>A systematic review and meta-analysis of observational studies was conducted to compare oral <i>H. pylori</i> prevalence between patients with oral diseases and healthy controls. Data were pooled to estimate overall associations, and subgroup analyses were performed by oral disease type, detection site, detection methods, and region to assess their potential impact on the observed relationships.</p> Results <p>Ten studies with 1166 participants met the inclusion criteria. Oral <i>H. pylori</i> infection was significantly associated with oral diseases (OR = 3.24, 95%CI:1.78–5.92, <i>p =</i> 0.0001), particularly periodontitis (OR = 4.28, 95%CI:2.46–7.44). The strongest associations were observed when H. pylori was detected in dental plaque (OR = 4.65, 95% CI: 2.60–8.33), using polymerase chain reaction (PCR)-based methods (OR = 4.09, 95% CI: 2.31–7.24), and in Asian populations. Sensitivity analyses confirmed the robustness of these results, and no publication bias was detected.</p> Conclusions <p>Oral <i>H. pylori</i>, particularly when detected in dental plaque by PCR, is strongly associated with periodontitis, suggesting that it may contribute to the progression of oral diseases. However, these findings are limited by potential confounding and the observational nature of the included studies, warranting cautious interpretation and further prospective research.</p> Clinical relevance <p>Oral <i>H. pylori</i> is associated with periodontitis, highlighting the need for standardized detection methods and further prospective studies to clarify causal mechanisms and guide integrated management of oral diseases and the risk of gastric reinfection.</p>