Complete colonic obstruction in children may occur secondary to congenital, and acquired factors related to the gastrointestinal system. Herein, we report an extraordinary presentation of complete colonic obstruction due to extensive urinary retention in a 3-year-old boy. The possible underlying mechanism was detected as urinary infection in a child with horseshoe kidney. The treatment of the bladder symptoms and urinary infection relieved the obstruction of the colon. To our knowledge, especially in children, colonic obstruction due to urinary retention has not been reported in the literature.