Gastric cancer (GC) is a leading cause of cancer-related mortality worldwide, with dietary factors significantly influencing GC risk. However, research on the dietary influences of GC in Middle Eastern populations, particularly in Jordan, remains limited. This study aimed to assess the association between the consumption of grains and legumes and GC risk in a Jordanian population, hypothesizing that refined grains may increase GC risk, while whole grains and legumes may offer protective effects. A case–control study was conducted involving 173 newly diagnosed GC cases and 314 cancer-free controls recruited from major hospitals in Jordan. Data were collected through interview-based questionnaires. Consumption of grains and legumes was assessed using a validated Arabic food frequency questionnaire tailored to Jordanian dietary habits. Statistical analyses were adjusted for key confounders to isolate the impact of dietary intake on GC risk. The findings indicate that a higher intake of refined grains, particularly white bread, is positively associated with an increased risk of GC, as shown by an odds ratio (OR) of 3.13 (confidence interval [CI]: 1.57 – 6.21, p = 0.001). In contrast, moderate rice consumption is linked to a reduced risk of GC (OR = 0.38, CI: 0.18 – 0.81). Legumes, including hummus (OR = 0.48, CI: 0.26 – 0.97) and cooked dried beans (OR = 0.40, CI: 0.20 – 0.81), were found to have protective associations with GC risk. However, the consumption of green peas was unexpectedly associated with an increased GC risk (OR = 2.19, CI: 1.24 – 3.88, p = 0.004), potentially due to preparation methods or consumption patterns. This study provides evidence linking specific grains and legumes to GC risk in Jordan. Refined grains appear to increase GC risk, while legumes may offer protective benefits. These findings underscore the importance of public health interventions that encourage increased consumption of legumes and discourage refined grain intake to mitigate GC risk in similar populations.