Despite the high prevalence of gastric diseases like gastric cancer and peptic ulcer disease attributed to Helicobacter pylori infections, there is still only a limited understanding of the underlying mechanisms. Existing in vitro models are either two-dimensional systems lacking the structural complexity of the gastric architecture, or complex three-dimensional systems that pose challenges for experimental access. In this study, we introduce a patterned homeostatic human gastric organoid-on-a-chip system with bilateral access that is capable of modeling H. pylori niche establishment and persistent colonization of the gastric epithelium. We show that in physiological apical acidic conditions, our organ-on-a-chip can generate pit cells of higher maturity in contrast to traditionally grown organoids. Upon infection with H. pylori for up to 6 days, these mature pit cells exhibit a distinctive response from other cell types, which was previously uncharacterized. Beyond its application in studying H. pylori infection, the increased structural and functional relevance of our model offers broader significance as a versatile platform for advancing our understanding of gastric epithelial cell interactions, gastric mucosal immunity, and host-pathogen interactions.