This paper reports the case of a 10-month-old male infant with Beckwith-Wiedemann syndrome (BWS) who presented with a reducible right inguinal mass and an empty scrotum for 10 months and was admitted for elective surgery. Preoperative ultrasonography revealed a right adrenal mass, which was pathologically diagnosed as ganglioneuroblastoma (GNB) after surgical excision. The patient exhibited characteristic features of BWS, including omphalocele, flame-shaped nevus on the forehead, bilateral earlobe creases, and embryonal tumor. Next-generation sequencing identified a heterozygous mutation in the CDKN1C gene (chr11:2905365), confirming the diagnosis of BWS. Early diagnosis, standardized management, and tumor surveillance are crucial for improving prognosis in children with BWS. Ultrasonography enables early detection of tumors and informs clinical decision-making regarding intervention.