Periodontitis is an oral chronic inflammatory disease initiated by plaque biofilm, which can lead to the destruction of periodontal supporting tissues, compromise oral health, and decrease the quality of life of patients. As the gateway to the gastrointestinal tract, oral pathogens can easily be transferred to the upper gastrointestinal tract through saliva swallowing, suggesting that the oral cavity may be a potential source of gastrointestinal tract diseases. Recent studies have indicated a potential correlation between periodontitis and upper gastrointestinal cancers (esophageal and gastric cancers). However, the causal relationship and specific mechanisms remain unclear. This article reviews the latest research progress on the relationship between periodontitis and upper gastrointestinal cancers, aiming to provide a reference for further investigation into the mechanisms underlying the association between these two diseases.