ObjectivesIt is not known whether cancer‐specific mortality (CSM) differences distinguish radical cystectomy (RC) from trimodal therapy (TMT) in octogenarians harbouring organ‐confined (T2N0M0) urothelial cancer of the urinary bladder (UCUB).MethodsWithin the Surveillance, Epidemiology, and End Results database (2004–2021), CSM and other‐cause mortality (OCM) rates were computed in octogenarian patients with organ‐confined UCUB undergoing either TMT or RC. Smoothed cumulative incidence plots depicted 5‐year CSM and OCM rates according to RC vs TMT. Competing risks regression (CRR) models were fitted, adjusting for age, gender, and race/ethnicity. Nearest‐neighbour 1:1 propensity‐score matching (PSM) for age and gender was also applied. Sensitivity analyses were additionally performed, focusing on White patients.ResultsOf 2335 octogenarian patients with T2N0M0 UCUB, 1562 (66.3%) received TMT and 793 (33.7%) received RC. Of those, 2082 (88.4%) were White. TMT rates increased from 53.5% in 2004 to 82.2% in 2021 (P < 0.001). The 5‐year CSM rate was 50.1% for TMT vs 31.1% for RC. After multivariable CRR, TMT independently predicted 1.7‐fold higher CSM (P < 0.001). After additional PSM, TMT also independently predicted 1.7‐fold higher CSM (P < 0.001). In sensitivity analyses exclusively focusing on White patients, almost identical results were recorded.ConclusionRates of TMT have nearly doubled in octogenarian patients with organ‐confined UCUB in recent years; however, CSM rates after TMT are also nearly twice as high as those observed after RC. It is crucial to communicate these observations.