Hyperosmolar hyperglycemic state (HHS) is a rare complication in children and a life-threatening emergency that presents with a significant increase in blood sugar and hyperosmolarity with or without low ketosis. This study reports the case of a 9-year-old boy with severe HHS due to type 1 diabetes. The patient’s initial serum glucose level was 1600; however, he was discharged in a stable condition. The patient presented many of the known complications of HHS, including decreased level of consciousness, hypovolemic shock, acute kidney injury, and very high serum glucose levels. The patient responded well to invasive fluid resuscitation and insulin administration, was discharged in good general condition without HHS-related complications, and was followed up with insulin therapy. As the prevalence of HHS in children is increasing, it is necessary for physicians to be aware of the unusual manifestations in children, especially children with type 1 diabetes, and to have the ability to diagnose and manage HHS and differentiate it from diabetic ketoacidosis.