Helicobacter pylori (H. pylori) is the major stomach carcinogen, but the molecular mechanism responsible for the pathogenesis of cancer development mediated by H. pylori infection is still unclear. Aquaporin 3 (AQP3), overexpressed in gastric carcinoma, has a crucial role in gastric carcinogenesis and progression. However, the triggers and precise regulations for AQP3 upregulation during gastric carcinogens also remain unknown. Here we report that H. pylori infection-mediated carcinogenesis may be mechanistically depended on the upregulation of AQP3 expression via reactive oxygen species (ROS) pathway activation in the stomach. The retrospective analyses of clinical samples from patients with gastric carcinoma and other different stages of gastric diseases indicated that AQP3 expression was positively associated with gastric mucosal disease progression and H. pylori infection status as well. Furthermore, H. pylori infection significantly upregulated AQP3 and HIF-1α expression and increased ROS amount in human gastric epithelial AGS and GES-1 cells. Blockage of ROS with inhibitors, NAC and DPI, markedly decreased the expression of AQP3 and HIF-1α in both AGS and GES-1 cells simultaneously. Furthermore, the increased AQP3 in cells was mechanistically due to the transcriptional regulation by HIF-1α. In addition, H. pylori infection exerted production of proinflammatory cytokines IL-6, IL-8, and TNF depending on AQP3 level. Importantly, these in vitro novel findings were further investigated in vivo in a mouse H. pylori infectious model. Our current studies identify the mechanistic link between H. pylori infection and AQP3 upregulation in the pathogenesis of gastric carcinoma, which involves the activation of the ROS-HIF-1α axis and the exacerbated ROS-HIF-1α-AQP3-ROS loop.