This case report describes a patient with known acute lymphoblastic leukemia (ALL) presenting with a rapidly enlarging and vision-threatening orbital mass. Orbital disease is rare in patients with ALL, and to our knowledge only six cases have been previously described, five of which are in children. We describe a 36-year-old Caucasian female with known acute lymphoblastic leukemia who developed markedly decreased visual acuity, proptosis, and elevated intraocular pressure over the course of 12 h. She was treated with emergent surgical intervention followed by intrathecal chemotherapy and intravenous steroids. Following medical and surgical intervention, the patient demonstrated rapid resolution of symptoms and a return to baseline visual acuity. The initial presentation of acute onset proptosis with optic nerve compromise can be suggestive of infectious etiologies, however, this case suggests caution in evaluation of patients with known systemic malignancy, particularly ALL, as early intervention with systemic steroids and surgery may result in return of visual function.