Aim The purpose of the present study was to examine whether the combination of subjective sleep quality and physical activity is associated with cognitive performance among community‐dwelling older adults. Methods Cross‐sectional data on 5381 older adults who participated in part of the National Center for Geriatrics and Gerontology – Study of Geriatric Syndromes were analyzed. We assessed general cognitive impairment using the Mini‐Mental State Examination, and also assessed story memory, attention, executive function and processing speed using the National Center for Geriatrics and Gerontology Functional Assessment Tool. Physical activity was assessed using two questionnaires, and participants were categorized as active or inactive. Sleep quality was assessed using the Pittsburgh Sleep Quality Index, and participants were categorized as having poor (PS) or good sleep quality (GS). Results Participants in the inactive + PS group had worse performances than those in the active + GS group in all cognitive measures (Mini‐Mental State Examination: P = 0.008, story memory: P = 0.007, other cognitive measures: P < 0.001), and also had worse performances than those in the inactive + GS and active + PS groups in the trail‐making test, part B, and the symbol digit substitution test (P < 0.001, respectively). Additionally, participants in the inactive + GS group had worse performances than in the active + GS in the trail‐making test, part B, and the symbol digit substitution test (P = 0.002 and P = 0.001, respectively). Conclusions Inactivity and poor sleep quality were associated with poor cognitive performance among community‐dwelling older adults. The combination of poor sleep quality and physical inactivity also worsened cognitive performance. Geriatr Gerontol Int 2017; ••: ••–••.