Background The benefit of adjuvant chemotherapy was investigated for patients with T3 upper urinary tract urothelial carcinoma (UTUC) who underwent radical nephroureterectomy. Methods This is a multicenter retrospective observational study of 482 patients with pathological T3 N0 and Nx UTUC who underwent radical nephroureterectomy with and without adjuvant chemotherapy. The median overall survival (OS), cancer-specific survival (CSS), and disease-free survival (DFS) of patients who received adjuvant chemotherapy were analyzed to determine predictors of patient prognosis. Results Of the 482 patients, 140 (29.0%) received adjuvant chemotherapy. Adjuvant chemotherapy showed a benefit only for the median DFS rate (58% vs 49%; p = 0.04). Multivariate analyses revealed that adjuvant chemotherapy improved median DFS (HR 0.537; CI 0.35–0.83; p = 0.005). Surgical margin also significantly influenced median OS (HR 4.038; p