Background: This study aimed to explore the relationship between Diabetes Risk Reduction Diet (DRRD) and bladder cancer risk in Prostate, Lung, Colorectal, Ovarian (PLCO) cohort. Methods: Data from 99,001 participants in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial were analyzed using Cox proportional hazards regression models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between DRRD score and bladder cancer incidence. Subgroup analyses were conducted to assess whether variables such as age, sex, BMI, cigarette smoking status, and history of diabetes influenced the observed association. The DRRD score was formulated based on nine nutrient intake indicators derived from the Dietary History Questionnaire. Results: During the median follow-up of 11.7 years, 761 new bladder cancer cases were identified. Participants with highest DRRD scores exhibited a reduced risk of bladder cancer compared to those in the lowest quartile (unadjusted analysis, hazard ratio [HR] = 0.65 [95% CI 0.53 to 0.82]; multivariable adjusted analysis, HR = 0.79 [95% CI 0.64 to 0.98], P-trend = 0.007). A similar risk reduction was seen solely in transitional cell carcinoma (HR = 0.79 [95% CI 0.64 to 0.99], P = 0.007). Additionally, the significant negative association between DRRD scores and bladder cancer risk persisted even after excluding participants with unique characteristics. Conclusion: This large prospective population-based study suggests that adherence to a DRRD may contribute to the prevention of bladder cancer. Impact: The DRRD could potentially mitigate bladder cancer risk, which warrants further validation in diverse populations.