Pubosymphyseal urinary fistula (PUF) is a rare condition that involves an abnormal connection between the urinary bladder and the pubic bone. It can occur after trauma, radiation therapy, or surgery to the pelvis. It is also reported with chronic indwelling Foley catheter use. In this case report, we present a 56-year-old male who developed a fistula complicated by osteomyelitis pubis following external beam radiation for a urinary bladder sarcomatoid tumor. Patients at high risk of PUF may present with urinary leakage, pelvic pain, and infection, making diagnosis challenging. The condition can lead to chronic pelvic pain and long-term opioid use if left untreated. Diagnosis is typically made through imaging studies (CT scan or MRI) and confirmed with cystoscopy. Treatment usually involves urinary diversion/surgical repair of the fistula and management of any associated infection or complications. The prognosis is generally good if the condition is diagnosed and treated promptly. While it is rare, it can have significant consequences that require prompt diagnosis and treatment.