Purpose: To identify the risk factors leading to radical cystectomy in patients who had undergone nephroureterectomy (NUx). Materials and Methods: We retrospectively reviewed the medical records of patients with upper tract urothelial carcinoma who underwent NUx during 2011–2019 and excluded patients with metastatic cancer. In total 646 patients were included in this study; of these, 532 had no previous bladder cancer history. Follow-up was performed every 3 months for 2 years after NUx was administered, and recurrence was confirmed using cystoscopy, urine cytology, computed tomography, and chest radiography. Bladder recurrence was confirmed through biopsy, urine cytology, or radiologic examination. Univariate and multivariate Cox regression analyzes were performed for statistical analysis of risk factors leading to radical cystectomy in patients undergoing NUx. Results: Lymphovascular invasion (LVI) (hazard ratio [HR], 4.728; 95% confidence interval [CI], 1.463–15.570; p=0.011), previous transurethral resection of bladder tumor history (HR, 3.825; 95% CI, 1.164–12.571; p=0.027), and intravesical recurrence (IVR) within 6 months (HR, 3.733; 95% CI, 1.091–12.778; p=0.036) in patients undergoing NUx are predictors of radical cystectomy implementation. In a multivariate analysis of patients without bladder cancer history, bladder recurrence was identified as a predictor of radical cystectomy implementation, if it occurred within 6 months of NUx (HR, 8.608; 95% CI, 1.545–47.976; p=0.014). Conclusions LVI and IVR within 6 months and previous bladder cancer history are factors that can predict the need for radical cystectomy after NUx. Even in patients without bladder cancer history, early bladder recurrence within 6 months is a major predictor of radical cystectomy.