Acute urinary retention is a very rare condition in pediatric population. Bladder diverticulum is usually not considered initially in the initial differential diagnosis. Herein we report a case of acute urinary retention due to bladder diverticulum. Our patient had antenatally diagnosed bilateral hydroureteronephrosis. Postnatal voiding cystourethrography demonstrated bilateral grade 5 vesicoureteral reflux. We decided to follow the patient on antimicrobial prophylaxis. After 1 year of follow-up, patient presented to the emergency department with failure to urinate. Ultrasonography and voiding cystourethrography demonstrated 2 giant bladder diverticula originating from bladder base and causing urethral obstruction. Bilateral diverticulectomy and bilateral transtrigonal ureteral reimplantation was performed. Voiding cystourethrography, which was carried out 6 months after the operation, demonstrated an urethra with normal caliber and no signs of vesicoureteral reflux or post-void residual urine Although encountered very rarely, bladder diverticula should always be considered in the differential diagnosis of acute urinary retention in pediatric population.