Urothelial carcinoma of the bladder in childhood is extremely rare. We report on a 12-year-old girl with urothelial carcinoma of the bladder who presented with gross hematuria. Immunohistochemical staining showed normal levels of cytokeratin 20 expression and decreased levels of Ki67 and p53 expression. Human papillomavirus, which can be a cause of urothelial carcinoma of the bladder, was not detected by polymerase chain reaction. We reviewed the literature focusing on diagnostic tools for urothelial carcinoma of the bladder and determined that abdominal ultrasonography, with an extremely high sensitivity of 98%, could be a useful tool for postoperative follow-up in childhood.