Pretibial myxedema (PM) is an unusual extrathyroidal manifestation of Graves’ disease (GD), which affects approximately 1%–5% of the patients. In addition, PM usually occurs in the hyperthyroid state of GD, and the high level of thyroid autoantibodies is considered to be the cause of PM. Here, we present a rare case of a patient who developed PM after undergoing I‑131 ablation therapy, with normal levels of thyroid autoantibodies. Our report aims to document the features of PM in a male adult with hypothyroidism and to provide a potential mechanism of the onset of PM.