Objective The Dietary Approaches to Stop Hypertension (DASH) diet is rich in recommended foods that are inversely associated with bladder cancer (BC) risk. The main objective of this study was to investigate the association between adherence to DASH diet and the risk of BC among Iranian adults. Method This study included 103 BC cases and 200 controls. The controls were patients who were hospitalised for acute non-neoplastic diseases. DASH scores were computed from dietary intake assessed by a previously validated food frequency questionnaire. Results After controlling for potential confounders, participants in the highest quintile of DASH (compared to the lowest quintile) had 84% lower BC risk (OR = 0.16; 95%CI: 0.05-0.45; p trend = 0.001). Among the DASH components, significant negative associations were observed between low fat dairy and whole grains intake with BC (p value < 0.05). A positive relation was observed for sodium, nuts and legumes, and sweetened beverages (p value < 0.05). Conclusion The results of this study suggested that adherence to DASH might be associated with reduced risk of BC. These findings could be used to develop evidence-based recommendations for the prevention of BC.