Background <p>Alien hand syndrome (AHS) is a rare neurological disorder characterized by involuntary, purposeful limb movements without voluntary control. While traditionally associated with frontal or callosal brain lesions, posterior cerebral artery (PCA) involvement remains sparsely reported, making such cases valuable for expanding understanding of the posterior variant of AHS.</p> Case Presentation <p>We report a 79-year-old male who presented with a witnessed generalized tonic–clonic seizure followed by acute right-sided weakness. Neurological examination revealed right upper limb movements, described by the patient as disconnected and involuntary. MRI showed an acute ischaemic infarct in the territory of the left posterior cerebral artery (PCA), involving the medial temporal, occipital, and posterior thalamic regions, which is an uncommon aetiology of AHS. The involuntary movements resolved spontaneously within two days without specific pharmacologic therapy.</p> Discussion <p>This case is noteworthy for its unique lesion distribution, initial presentation with seizure, and rapid resolution of symptoms. To our knowledge, few reports have described this precise anatomical pattern with transient symptoms. Additionally, the initial presentation with a generalized tonic–clonic seizure preceding alien-hand manifestations represents an uncommon clinical course.</p> Conclusion <p>This case underscores the importance of recognizing AHS as a possible early manifestation of posterior circulation stroke, enabling prompt imaging and intervention.</p>