To determine the quality of life (QoL) of patients with muscle-invasive bladder cancer (MIBC) who underwent bladder-sparing treatment with high-dose-rate brachytherapy, and compare their QoL with an age-matched general Dutch population. We conducted a single-center, prospective, descriptive cross-sectional study. MIBC patients who underwent brachytherapy-based bladder sparing treatment in Arnhem, The Netherlands from January 2016 to June 2021, were requested to complete the following questionnaires: European Organization for Research and Treatment of Cancer (EORTC) generic (QLQ-C30), bladder cancer-specific (QLQ-BLM30), and expanded prostate cancer index composite bowel (EPIC-50). Mean scores were calculated and compared with general Dutch population. The mean global health status/QoL score of the treated patients was 80.6. High scores were noted in the functional scales, including physical (86.8), role (85.6), emotional (88.6), cognitive (88.3), and social functioning (88.9), while the main reported complains were related to fatigue (21.9) and urinary symptoms (25.1). Compared to the general Dutch population, significant differences were visible in global health status/QoL (80.6 vs. 75.7), pain (9.0 vs. 17.8), insomnia (23.3 vs. 15.2), and constipation (13.3 vs. 6.8). However, in no case did the mean score differ by more than ten points, which was considered clinically relevant. With a mean global health status/QoL score of 80.6, the patients after brachytherapy-based bladder sparing treatment have a good QoL. We found no clinically relevant difference in QoL comparing with an age-matched general Dutch population. The outcome strengthens the idea that this treatment option should be discussed with all patients eligible for brachytherapy-based treatment.