Persistent infection with Helicobacter pylori (HP) within the stomach causes chronic gastritis, an essential precursor to gastric cancer. Genetic polymorphisms in the IL18 gene strongly correlate with an increased risk of atrophic gastritis and gastric cancer, yet the activation and regulation of this cytokine in HP inflammation remain poorly understood. It has been reported that NOD-like receptor (NLR) family member NLRP3 sense microbial components and mediate secretion of active IL-18 in myeloid cell linages through “inflammasome” assembly upon HP infection. By using bone-marrow chimeric mice, however, we identified non-hematopoietic cells as being the major source of IL-18 in the gastric mucosa of HP-infected mice and showed that loss of IL-18 in this cell compartment resulted in mucosal hyperplasia and increased acid mucins. Given that gastric epithelial cells (GECs) express the NLR protein NOD1, which detects Gram-negative bacterial peptidoglycan and plays an important role in host immunity against HP infection, we further investigated the involvement of this receptor in HP-associated IL-18 responses. Here, we demonstrated that HP or HP-derived outer membrane vesicles induce mature IL-18 secretion in both mouse and human GECs. Gene knockdown showed that the HP-induced IL-18 secretion is driven by NOD1 receptor which interacts with caspase-1 via its caspase-activation recruitment domain (CARD), resulting in processing of pro-IL-18. Using the three-dimensional gastric tissue (organoid) injected with HP, we demonstrated that NOD1 is required for maintaining the balance between epithelial proliferation and apoptosis. Collectively, this is the first study, to our knowledge, reveals an unanticipated function of NOD1 signaling in posttranslational regulation of IL-18 in GEC and an important role for NOD1/IL-18 signalling in maintaining gastric mucosal homeostasis. These findings suggest a rationale to target this signalling in HP-infected patients to reduce the risks of developing gastric cancer.