Granulocytic sarcoma (chloroma) is a rare malignant solid tumor representing an extramedullary manifestation of acute myeloid leukemia (AML). Rarely, a chloroma can develop as the sole manifestation and its appearance may precede the systemic manifestations of acute myelocytic leukemia by months to years. We report a rare case of unilateral orbital mass presenting with progressive proptosis involving left globe in an otherwise healthy child, and give a brief overview of the literature about this unusual presentation. Leukemic infiltration should be considered in the differential diagnosis of orbital masses and proptosis even in the absence of systemic manifestations of AML. Early detection and management are crucial to preserve vision and prevent complications.