Point mutations in the TERT gene promoter occur at high frequency in multiple cancers, including urothelial carcinoma (UC). However, the relationship between TERT promoter mutations and UC patient outcomes is unclear due to conflicting reports in the literature. In this study, we examined the association of TERT alterations, tumor mutational burden per megabase (Mb), and copy number alteration (CNA) burden with clinical parameters and their prognostic value in a cohort of 398 urothelial tumors. The majority of TERT mutations were located at two promoter region hotspots (chromosome 5, 1 295 228 C>T and 1 295 250 C>T). TERT alterations were more frequently present in bladder tumors than in upper tract tumors (73% vs 53%; p=0.001). ARID1A, PIK3CA, RB1, ERCC2, ERBB2, TSC1, CDKN1A, CDKN2A, CDKN2B, and PTPRD alterations showed significant co-occurrence with TERT alterations (all p<0.0025). TERT alterations and the mutational burden/Mb were independently associated with overall survival (hazard ratio[HR] 2.31, 95% confidence interval [CI] 1.46-3.65; p<0.001; and HR 0.96, 95% CI 0.93-0.99; p=0.002), disease-specific survival (HR 2.23, 95% CI 1.41-3.53; p<0.001; and HR 0.96, 95% CI 0.93-0.99; p=0.002), and metastasis-free survival (HR 1.63, 95% CI 1.05-2.53; p=0.029; and HR 0.98, 95% CI 0.96-1.00; p=0.063) in multivariate models. PATIENT SUMMARY: The majority of TERT gene mutations that we detected in urothelial carcinoma are located at two promoter hotspots. Urothelial tumors with TERT alterations had worse prognosis compared to tumors without TERT alterations, whereas tumors with a higher mutational burden had more favorable outcome compared to tumors with low mutational burden.