Abstract Purpose Pre-operative assessment of surgical risk is essential for patient counselling in the elderly patient population. Our purpose was to compare validated geriatric assessment scores (GAS) in predicting postoperative morbidity and mortality in patients ≥ 80 years. Methods Overall, eight preoperative GAS were assessed for each patient who received RC from 2016 to 2021. Postoperative morbidity was recorded according to the Clavien-Dindo classification (CDC) of surgical complications. Binary logistic regression analyses were used to determine prediction of 30-d morbidity and 90-d mortality in patients ≥ 80 years. Results In total, 424 patients were analysed (77.4% male) with median age of 71 years (IQR: 68.82;70.69), of which 67 (15.8%) were ≥ 80 years. Patients age ≥ 80 years showed more 30-d CDC grade ≥ IIIb (41.07% vs. 27.74% compared to < 80 years, p < .001) and worse 90-d mortality (26.87% vs. 4.76%, p < .001). In patients ≥ 80 years, morbidity was predicted by simplified Frailty Index (sFI) ≥ 2 (OR: 2.06, 95% CI: 1.27–3.34, p = .004), Eastern Cooperative Oncology Group (ECOG) performance status ≥ 2 (OR: 2.78, 95% CI: 1.18–6.54, p = .019) and severe Adult Comorbidity Evaluation (ACE)-27 score (OR: 2.07, 95% CI: 1.13–3.79, p = .019), while 90-d mortality was predicted by CDC grade ≥ IIIb (OR: 22.91, 95% CI: 8.74–60.09, p < .001) and ECOG ≥ 2 (OR: 2.87, 95% CI: 1.05–7.86, p = .04). Conclusion Even in a high-volume center of RC, 90-d mortality is significantly higher in patients age ≥ 80. Our results suggest in patient age ≥ 80, sFI ≥ 2, ECOG performance status ≥ 2 and severe ACE-27 score as clinical cut-off value to evaluate alternative bladder-sparing concepts.