Spontaneous retrobulbar hemorrhage is a rare yet vision-threatening condition. We reported a 5-month-old male infant with sudden onset of left eye proptosis with no prior history of getting vitamin K injection after birth. Head computed tomography scan revealed retrobulbar and intracranial hemorrhages. Laboratory results showed anemia, prolonged prothrombin and activated partial thromboplastin time, supporting the diagnosis of vitamin K deficiency bleeding. After the bleeding and clotting profile were stabilized, lateral canthotomy and cantholysis; and drainage following orbital decompression were successfully performed, yielded in a completely resolved proptosis. The right timing for surgery with the goal of releasing intraorbital pressure represent the merit of this paper. Our case also led to a crucial emphasis on vitamin K prophylaxis at birth. © 2021 Wolters Kluwer Health, Inc.