Objectives The idea that delirium is a risk factor for dementia, broadly defined, is derived from heterogeneous patient samples. We reviewed available evidence as to whether stroke survivors who developed delirium during the acute phase of treatment are at a higher prospective risk of incident post‐stroke cognitive impairment or dementia. Design We searched 8721 records in the Cochrane database for reviews or protocols dealing with the study objective, Medline, EMBASE, PsycInfo and CINAHL for observational studies in the general adult population and PubMed for in‐process articles. Additional searches of the reference lists of retrieved articles were also undertaken. Qualitative syntheses and meta‐analysis were conducted according to conventional guidelines. Results Twelve relevant articles were fully appraised. Four out of these studies, comprising 743 stroke survivors, including 199 with delirium, met criteria for qualitative syntheses. Overall, the studies presented low to moderate level evidence suggesting an association between post‐stroke delirium and dementia. Conclusions There is a need for further studies to investigate the association of post‐stroke delirium and dementia using well‐defined cohorts of patients and controlling for factors such as pre‐stroke cognition, stroke severity and location and the presence of persistent delirium. Such studies will help understand the place of delirium identification and prevention in reducing the risk of dementia after stroke. © 2016 The Authors. International Journal of Geriatric Psychiatry Published by John Wiley & Sons Ltd