Hashimoto’s encephalopathy (HE) is a rare disease of the central nervous system characterized by diverse neurological symptoms associated with elevated levels of antithyroid antibodies. Posterior reversible encephalopathy syndrome (PRES) is a clinico-radiological syndrome characterized by typical manifestations such as severe headache, altered mental status, visual impairment, seizures, and vasogenic edema. We experienced a patient with HE presenting with PRES who showed remarkable improvement subsequent to treatment with anti-seizure medication and corticosteroids. This case report underscores potential pathomechanisms and clinical significance.