Despite being the fourth and eighth most common cancer in US men and women, respectively, bladder cancer (predominantly of urothelial histology in the US and Europe) paradoxically remains a disease entity less frequently encountered by radiation oncologists in comparison to even rarer cancers. This is mainly attributed to the fact that approximately 70–80% of diagnosed urothelial bladder cancers have not invaded the detrusor smooth muscle and consequently are treated with an endoscopic transurethral bladder tumor resection (TURBT), with or without intravesical therapy. In patients with muscle-invasive bladder cancer (MIBC) or those who have recurred after multiple TURBTs, radical cystectomy has been considered the preferred therapy in the US, despite a lack of high-quality evidence comparing its efficacy to definitive radiation therapy. However, with an aging and comorbid population unsuitable for surgery, contraindications for neoadjuvant cisplatin, and patient preference, bladder-sparing definitive radiotherapy has gained popularity. Trimodality definitive therapy (TMT) consisting of a maximal TURBT followed by concurrent chemoradiation is an established alternative treatment approach to radical cystectomy; data suggest comparable long-term disease control in appropriately selected patients. Although adjuvant radiation has been used in cases where there is a high risk of pelvic recurrence post-cystectomy (i.e., pT3-4 disease, pathologically nodal metastases, positive surgical margins), we typically do not follow this practice given the limited data and high toxicity rates.