Rapidly progressing orbital liposarcomas, while rare, pose significant diagnostic challenges due to their varied clinical and radiological presentations. A 76-year-old female presented with a suspected well-differentiated orbital liposarcoma 16 months after the onset of proptosis and diplopia. Initial magnetic resonance imaging (MRI) revealed a homogeneous, high-intensity mass in the left superior orbit. Although oral corticosteroids were administered, the patient's condition worsened over the following 13 months, with subsequent MRI revealing a heterogeneous mass. Orbital exenteration was performed, and histopathological analysis confirmed the diagnosis of a well-differentiated liposarcoma despite the rapid progression and imaging changes. This case highlights that rapid clinical and radiological changes in orbital liposarcomas do not necessarily indicate dedifferentiation. The discrepancy between imaging progression and histopathological findings emphasizes the critical role of pathological evaluation in making a definitive diagnosis. Treatment decisions, including aggressive surgical approaches, should be based on a comprehensive assessment of the clinical presentation, imaging features, and histopathological characteristics tailored to the individual patient's condition and disease progression.