Bacillus Calmette-Guérin (BCG) therapy is an adjuvant treatment for urothelial carcinomas of the upper urinary tract (UTUC). BCG therapy can result in various side effects. We present a case of a 67-year-old female with a history of UTUC who developed disseminated tuberculosis following BCG instillation into the upper urinary tract after conservative management. This complex clinical scenario required a multidisciplinary approach, including antibiotic therapy, immunoglobulin infusion, and tailored tuberculosis treatment. The case underscores the importance of vigilance, early detection, and tailored interventions in managing disseminated tuberculosis arising from BCG therapy and rare complications like hemophagocytic syndrome.