AbstractCognitive differences in memory, information processing speed (IPS), and executive functions (EF), are common in autistic and high autistic trait populations. Despite memory, IPS and EF being sensitive to age‐related change, little is known about the cognitive profile of older adults with high autistic traits. This study explores cross‐sectional memory, IPS and EF task performance in a large sample of older adults in the online PROTECT cohort (n = 22,285, aged 50–80 years), grouped by high vs. low autistic traits. Approximately 1% of PROTECT participants (n = 325) endorsed high autistic traits [henceforth Autism Spectrum Trait (AST) group]. Differences between AST and age‐, gender‐, and education‐matched comparison older adults (COA; n = 11,744) were explored on memory, IPS and EF tasks and questionnaires administered online. AST had lower performance than COA on tasks measuring memory, working memory, sustained attention, and information processing. No group differences were observed in simple attention or verbal reasoning. A similar pattern of results was observed when controlling for age, and current depression and anxiety symptoms. In addition, AST self‐reported more cognitive decline than COA, but this difference was not significant when controlling for current depression symptoms, or when using informant‐report. These findings suggest that autistic traits are associated with cognitive function in middle‐aged and later life. Older adults with high autistic traits experienced more performance difficulties in a range of memory, IPS and EF tasks compared with the low autistic traits comparison group. Further longitudinal work is needed to examine age‐related change in both older autistic and autistic trait populations.