Functional neurological disorders may present with cognitive symptoms as functional cognitive disorders. This narrative review addresses the diagnosis and differential diagnosis of functional cognitive disorders encountered in the emergency department setting. Functional cognitive disorders, like other functional neurological disorders, can be clinically suspected and may be positively diagnosed in the emergency department setting following careful diagnostic evaluation, rather than being a diagnosis of exclusion. However, the differential diagnosis is broad, and the possibility of either stroke or seizure in particular needs to be considered. Functional cognitive disorders can be positively diagnosed in the emergency department setting, as for other forms of functional neurological disorder, and hence directed onward to appropriate services.