Objective Cognitive impairment has been associated with late‐life suicidal behavior. Without longitudinal data it is unclear whether these are transient features of a depressive state or stable impairments. We examined longitudinally the course of cognitive impairment in older adults with depression and a history of suicide attempt. Methods We investigated the persistence of cognitive impairment over time in 198 depressed older adults (age >60); 91 suicide attempters, 39 depressed individuals with suicidal ideation (ideators), and 68 non‐suicidal depressed adults assessed over a 2‐year period at four time points. We used linear mixed effects modeling to examine group differences in trajectories of cognitive decline over 2 years, using the Mini‐Mental State Examination (MMSE), Mattis Dementia Rating Scale (DRS), and Executive Interview (EXIT). Results Over the 2‐year period, suicide attempters performed significantly worse than both suicide ideators and non‐suicidal depressed older adults on the MMSE (mean difference: from ideators: −0.88, p = 0.02; from non‐suicidal depressed: −1.52, p < 0.01), while on the EXIT and DRS, suicide attempters performed significantly worse than non‐suicidal depressed older adults (mean difference: in EXIT: −1.75, p = 0.01; in DRS: 3.04, p < 0.01; in MMSE: 1.15, p < 0.01). Cognitive impairment in suicide attempters partly resolved, as indicated by a group × time interaction on the DRS (p = 0.039), but not the EXIT (p = 0.58) or the MMSE (p = 0.08). Conclusions Cognitive impairment in late‐life suicidal behavior appears to involve both a stable and a state‐related component. Copyright © 2015 John Wiley & Sons, Ltd.