Spontaneous rupture of the ureter is an uncommon condition defined by non-traumatic extravasation of urine. Causative factors leading to rupture include urinary calculi, malignancies, instrumentation or trauma. Ureteral rupture can lead to numerous complications, including abscess formation, urinomas, and urosepsis. Minimal literature is available regarding spontaneous ureteral perforation, especially at the ureteropelvic junction. We present a rare case of spontaneous perforation of the ureter at the ureteropelvic junction caused by an undiagnosed non-compliant bladder. This case illustrates a previously undescribed cause of spontaneous ureteral perforation and the importance of prompt identification and treatment.