Osteolipoma is a rare lipoma variant characterized by mature osseus metaplasia within mature adipose tissue, most commonly found in the head and neck, and seldom reported in the extremities. We present a case of a large osteolipoma of the posterior ankle associated with antecedent trauma. These tumors are typically slow growing and can be associated with pain and stiffness, depending on tumor size and location. Treatment is surgical excision, and recurrence is not reported. Interdisciplinary care involving radiology, pathology, and the surgical service is necessary for proper diagnosis and treatment of this rare benign neoplasm.