Purpose In the phase III KEYNOTE-045 study ( ClinicalTrials.gov identifier: NCT02256436), pembrolizumab significantly prolonged overall survival compared with investigator's choice of chemotherapy in patients with previously treated advanced urothelial cancer. Here, we report the results of health-related quality-of-life (HRQoL) analyses from the KEYNOTE-045 trial. Patients and Methods Patients were randomly assigned 1:1 to pembrolizumab 200 mg or investigator's choice of docetaxel 75 mg/m2, paclitaxel 175 mg/m2, or vinflunine 320 mg/m2 administered intravenously every 3 weeks. Key prespecified HRQoL analyses were time to deterioration (TTD) and mean change from baseline to week 15 in European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire C30 global health status/quality-of-life score. Results Of 542 patients who were randomly assigned, 519 were included in HRQoL analyses (pembrolizumab, n = 266; chemotherapy, n = 253). HRQoL compliance was > 95% at baseline and approximately 88% at week 15 for both groups. Pembrolizumab prolonged TTD in global health status/quality-of-life score compared with chemotherapy (median, 3.5 months v 2.3 months; hazard ratio, 0.72; nominal one-sided P = .004). Mean (95% CI) change from baseline to week 15 in global health status/quality-of-life score was 0.69 (-2.40 to 3.77) with pembrolizumab and -8.36 (-11.84 to -4.89) with chemotherapy (mean difference, 9.05 points; 95% CI, 4.61 to 13.50; nominal two-sided P < .001). Conclusion Pembrolizumab prolonged TTD in HRQoL compared with chemotherapy. Patients who were treated with pembrolizumab had stable or improved global health status/quality of life, whereas those who were treated with investigator's choice of chemotherapy experienced declines in global health status/quality of life. Combined with efficacy and safety outcomes, these data support pembrolizumab as standard of care for patients with platinum-refractory advanced urothelial cancer.