Moyamoya disease (MMD) is a progressive steno-occlusive cerebrovascular disorder characterized by bilateral internal carotid artery occlusion and compensatory formation of fragile collateral vessels. While ischemic and hemorrhagic events are the most recognized presentations, headache is an increasingly acknowledged but underdiagnosed symptom of MMD, particularly in adult patients. In this chapter, we present a case of a 51-year-old woman with a long-standing history of migraine-like headaches who experienced a sudden increase in attack frequency and severity, ultimately leading to the diagnosis of Moyamoya disease. The case illustrates how a headache can serve as a sentinel symptom, offering an early window for diagnosis before irreversible cerebrovascular events occur. We explore the underlying pathophysiological mechanisms of Moyamoya-related headaches, including cerebral hypoperfusion, collateral vessel formation, and impaired autoregulation. A detailed discussion of differential diagnoses—including migraine, reversible cerebral vasoconstriction syndrome (RCVS), vasculitis, dissection, cerebral venous sinus thrombosis (CVST), and tumors—is provided, emphasizing the role of neuroimaging in distinguishing primary from secondary headache disorders. Given the potential for misdiagnosis and harmful therapeutic missteps (e.g., vasoconstrictor use), heightened clinical awareness is critical. This chapter concludes with key clinical messages and future directions, emphasizing the need for further research into Moyamoya-associated headache phenotypes, treatment protocols, and the integration of multidisciplinary care.