To evaluate the impact of preoperative renal impairment on the oncological outcomes of patients with urothelial carcinoma who underwent radical cystectomy. We retrospectively reviewed the medical records of patients with urothelial carcinoma who underwent radical cystectomy from 2004 to 2017. All patients who underwent preoperative 99mTc-diethylenetriaminepentaacetic acid renal scintigraphy (DTPA) were identified. We divided the patients into two groups according to their glomerular filtration rates (GFRs): GFR group 1, GFR≥90 mL/min/1.73 m²; GFR group 2, 60≤GFR<90 mL/min/1.73 m². We included 89 patients in GFR group 1 and 246 patients in GFR group 2 and compared the clinicopathological characteristics and oncological outcomes between the two groups. The mean time required for recurrence was 125.5±8.0 months in GFR group 1 and 85.7±7.4 months in GFR group 2 (p=0.030). The mean cancer-specific survival was 131.7±7.8 months in GFR group 1 and 95.5±6.9 months in GFR group 2 (p=0.051). The mean overall survival was 123.3±8.1 months in GFR group 1 and 79.5±6.6 months in GFR group 2 (p=0.004). Preoperative GFR values in the range of 60≤GFR<90 mL/min/1.73 m² are independent prognostic factors for poor recurrence-free survival, cancer-specific survival, and overall survival in patients after radical cystectomy compared with GFR values of ≥90 mL/min/1.73 m².