<b><i>Introduction:</i></b> Despite the fact that guidelines recommend monitoring of quality of life during all phases of treatment in urothelial carcinoma, prospective data about health-related quality of life (HRQoL) in metastatic urothelial carcinoma undergoing immunotherapy are sparse. Consequently, we performed a prospective clinical pilot study about HRQoL using the Functional Assessment of Cancer Therapy – Immune Checkpoint Modulator (FACT-ICM) questionnaire. <b><i>Materials and Methods:</i></b> Formally, this study is a prospective uni-centric noninterventional observation from January 2021 to December 2021. <b><i>Results:</i></b> Fourteen patients with a mean age of 73.9 years (SD 8.8) participated in the study. The physical well-being subscale of FACT-G is most impaired during therapy with mean scores of 7.5, 6.2, and 4.0 followed by the emotional well-being. The FACT-G total score is stable during therapy with mean scores of 51.1, 50.4, and 48.0 and it is not significantly decreasing during therapy (<i>p</i> = 0.317). Furthermore, the symptom burden of these patients is low and not significantly changing over time (<i>p</i> = 0.500), but survival decreases significantly if symptom burden is high (FACT-ICM score over 40; <i>p</i> < 0.001). <b><i>Conclusion:</i></b> Physical and emotional needs have a strong impact on HRQoL and should be dealt with during treatment. If symptom burden is high, survival decreases. This needs further evaluation.