Objectives: The objectives of the study are to evaluate the oncological and functional outcomes of three bladder preservation regimens: radiotherapy alone (RT-alone group), concurrent chemoradiotherapy (CRT) using gemcitabine plus platinum (GP-RT group), and low-dose gemcitabine (LD-Gem-RT group) for muscle-invasive bladder cancer. Methods: The three oncological outcomes, bladder-intact distant metastasis-free survival (BI-DMFS), cancer-specific survival, and overall survival (OS), were compared among RT alone (n = 10), GP-RT (n = 16), and LD-Gem-RT (n = 11) groups. Treatment-related adverse events were evaluated against the Common Terminology Criteria for Adverse Events (version 5.0). In the LD-Gem-RT group, time-course changes in the domains and scales related to the quality of life were evaluated by utilizing three questionnaires. Results: Age was significantly higher in the RT alone group (84 ± 7.2 years old) than in the GP-RT (74 ± 9.0) and LD-Gem-RT (75 ± 6.7) groups (P = 0.016). At a median follow-up of 26 months, the 2-year BI-DMFS rates were 80, 81, and 55% in the RT alone, GP-RT, and LD-Gem-RT groups, respectively, and the 2-year OS rates were 69, 62, and 81%, respectively. In the CRT groups, only the baseline CRP ≥ 1.0 mg/dL was associated with poor survival outcomes. Common early-onset adverse events included diarrhea, urinary frequency, and hematotoxicity. A questionnaire survey in the LD-Gem-RT group revealed patients experienced significant deterioration in the global health status/quality of life and the physical component summary score. Conclusion: We reported the oncological and functional outcomes of bladder preservation therapy using three different regimens, yielding acceptable outcomes.