Duodenal web (DW) is a rare congenital anomaly of the intestinal tract that can lead to severe dehydration and electrolyte imbalance. A 14-day-old boy presented with recurrent vomiting and weight loss and was diagnosed with DW. Duodenoscopy identified a pinhole structure in the second portion of the duodenum, prompting a subsequent endoscopic balloon dilatation procedure. Following the procedure, vomiting and abdominal distension resolved, and the patient was discharged on a regular diet. No symptoms recurred during follow-up.