Background: Neoadjuvant chemotherapy (NAC)-induced acute kidney injury (AKI) is a frequent complication in patients with muscle-invasive bladder cancer (MIBC). Although previous studies have reported that AKI during cancer treatment was associated with poor oncological outcomes in several cancers, the impact of NAC-induced AKI on oncological outcomes in patients with MIBC remains unclear. Methods: This retrospective study included 398 patients who received 2-4 cycles of NAC followed by radical cystectomy (RC). AKI was defined according to the KDIGO criteria. Patients were divided into two groups: patients who developed AKI during NAC (AKI group) and patients who did not (non-AKI group). Multivariable Cox-proportional hazards regression analyses were performed to evaluate the impact of NAC-induced AKI on recurrence-free survival (RFS), cancer-specific survival (CSS), and overall survival (OS). Results: The median age and follow-up period were 69 years and 62 months, respectively. Of the 398 patients, 66 (17%) developed AKI during NAC. The rates of <ypT2 and downstage in the AKI group were significantly lower than those in the non-AKI group (38% vs. 53%, P = 0.023; 53% vs. 69%, P = 0.013; respectively). After adjustment for age, performance status, cisplatin-based regimen, tumor grade, pathological T stage, pathological lymph-node involvement, and positive surgical margin, AKI was associated with shorter RFS (hazard ratio [HR] 1.619, P = 0.043), CSS (HR 1.727, P = 0.049), and OS (HR 1.848, P = 0.008). Conclusions: NAC-induced AKI was associated with reduced effects of NAC and poor oncological outcomes in patients who underwent RC.