Objective This systematic review describes the current functional neuroimaging literature in delirium, discusses pathophysiological implications of these results and highlights areas for further study. Methods In accordance with Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines, an extensive search of medical databases was undertaken, identifying eighteen studies of variable quality and design suitable for inclusion. Results Functional neuroimaging has highlighted significant abnormalities during delirium, with disturbances in cerebral haemodynamics and functional connectivity potentially playing a key role in delirium pathophysiology. Conclusions Although employing functional neuroimaging in delirium remains difficult, these findings demonstrate the potential of functional imaging to increase our understanding of the underlying mechanisms of delirium, to lead to more efficient interventions and targeted therapies and to reduce the burden of this underdiagnosed syndrome.