Background: Immune checkpoint inhibitors (ICIs) have revolutionized the care of patients with genitourinary (GU) cancers however many of the clinical trials that have led to the approval of ICIs in GU cancers often have low enrollments of older patients aged 65 and above for which safety data in this cohort is limited. Methods: A retrospective study was performed that included all patients aged 65 and older with kidney, bladder, and upper tract urothelial carcinoma (UTUC), who were treated at the University of Florida Health Cancer Center between January 2018 and September 2022, and received at least one dose of ICI (pembrolizumab, nivolumab, ipilimumab with nivolumab, avelumab, or atezolizumab). Data was collected on all documented immune related adverse events (irAEs) that were deemed attributable to the checkpoint inhibitor by the treating provider. The grading of toxicities was determined by the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Results: We identified a total of 139 patients who met the inclusion criteria of our study. The ages of patients ranged from 65 to 93 and the median age was 74. Females accounted for 31 patients (22%) while 108 patients (78%) were male. There were 56 patients (40%) with bladder cancer, 58 patients (42%) with kidney cancer, and 25 patients (18%) with UTUC. An irAE was documented in 76 patients (55%) while 63 patients (45%) had no documented irAE. Patients were categorized by the highest grade of toxicity experienced. A Grade 1 toxicity was found in 15 patients (11%), while a grade 2 toxicity was found in 41 patients (29%), with 18 patients (13%) having a grade 3 toxicity, and 2 patients (1%) experiencing a grade 4 toxicity. There were no documented grade 5 toxicities, i.e. no deaths were directly attributed to treatment. We found that 27 patients (19%) required either oral or intravenous steroids to manage their irAE. Discontinuation of treatment due to an irAE was observed in 16 patients (12%). Inpatient hospitalization due to an irAE occurred in 12 patients (9%). Conclusions: Our study demonstrates that the majority of patients aged 65 and older either have no irAEs or developed mild irAEs when treated with ICIs. Severe and life-threatening adverse events are uncommon, rarely require hospital admission, and did not lead to any deaths. This study should help to provide valuable information on the safety of checkpoint inhibitors in older patients with GU cancers and assist in the shared decision-making process for cancer treatment.