Objective: The aim of this study was to investigate whether diagnostic ureteroscopy (URS) biopsy is unfavourable for bladder tumour recurrence in upper urinary tract urothelial carcinoma (UTUC). Materials and Methods: We performed a retrospective analysis of 195 patients diagnosed with UTUC, who were divided into a diagnostic URS group (URS+) and a nondiagnostic URS group (URS–) according to whether diagnostic ureteroscopic biopsy was performed. A Cox regression model was used to analyse the risk factors for intravesical recurrence (IVR)-free survival (IRFS) and overall survival (OS) in UTUC after radical nephroureterectomy (RNU). Kaplan-Meier analysis was used to estimate the influence of factors on the incidence of IVR and the cumulative survival rate of UTUC. Results: Patients with a maximum tumour diameter of less than 3.1 cm, low-stage tumours, and ureteral tumours were more likely to undergo diagnostic URS before radical surgery. Multivariate Cox regression analysis showed that tumour pathological stage and diagnostic ureteroscopic biopsy can be used as predictors of IVR after RNU (p = 0.019, 0.033). Kaplan-Meier survival analysis found that diagnostic ureteroscopic biopsy was a high-risk factor for IRFS (p = 0.034). Subcomponent analysis showed that pTa/Tis/T1, pT2, pT3/pT4 stage, and diagnostic ureteroscopic biopsy with pTa/Tis/T1 stage were unfavourable for IVR (p = 0.047). Conclusion: Diagnostic ureteroscopic biopsy before RNU should be carefully selected for patients with atypical preoperative UTUC. We believe that intravesical chemotherapy drug perfusion can be used after surgery to prevent IVR if biopsy is unavoidable, but this still requires further prospective studies.