Background and aim <p>This study investigated the relationship between preoperative Modified 5-item Frailty Score (mFI-5) and long-term survival as well as 30-day postoperative complications in patients who underwent radical cystectomy for bladder cancer.</p> Methods <p>Patients who underwent radical cystectomy between 2012–2023 were analyzed and divided into two groups based on their mFI-5 scores: low-risk (≤ 1) and high-risk (≥ 2). Overall survival (OS), cancer-specific survival (CSS), and 30-day postoperative complications were compared between these groups. Additionally, Cox proportional hazards regression analysis was used to examine the impact of the mFI-5 score on OS and CSS.</p> Results <p>Our study included 288 patients with an average age of 63.8 ± 9.1&#xa0;years at the time of surgery. Patients with a low mFI-5 score comprised 77.4% (<i>n</i> = 223) of the cohort, while 22.6% (<i>n</i> = 65) had a high mFI-5 score. The majority of patients had advanced-stage disease (pT3-pT4 for 53.8% (<i>n</i> = 155)). Patients with a high mFI-5 score demonstrated significantly worse OS and CSS compared to those with a low mFI-5 score (<i>p</i> = 0.002 and <i>p</i> = 0.007, respectively). Although 30-day mortality rates were significantly higher in the high mFI-5 score group (<i>p</i> = 0.002), the difference in overall complication rates was not statistically significant (<i>p</i> = 0.120). In multivariate Cox proportional hazards analysis, the mFI-5 score was identified as an independent predictor for both OS and CSS (<i>p</i> = 0.001 and <i>p</i> = 0.003, respectively).</p> Conclusion <p>mFI-5 score can provide valuable prognostic information regarding survival after radical cystectomy in bladder cancer patients, based on preoperative findings. It is an independent predictor of long-term survival.</p>