INTRODUCTION: The association between cognitive function, healthy lifestyle, and mortality remains understudied in large Chinese cohorts. METHODS: In this nationwide 10-year prospective study of 24,657 older adults, we assessed Mini-Mental State Examination (MMSE) categories (<
18, 18 to 23, 24 to 27, 28 to 30) and a seven-component lifestyle score (0 to 7) for their relationships with all-cause, cardiovascular, and cerebrovascular mortality. RESULTS: Compared with individuals scoring 28 to 30 on the MMSE, lower scores were linked to elevated all-cause and cerebrovascular mortality but not cardiovascular mortality. Participants with lifestyle scores of 4 or 5 had a higher risk of all-cause mortality. Even optimal lifestyle practices did not fully mitigate the heightened mortality risk associated with declining cognitive performance. DISCUSSION: A healthy lifestyle is beneficial but cannot fully offset the impact of cognitive impairment. Therefore, integrating routine cognitive assessments and targeted interventions with healthy lifestyle practices is crucial for effectively reducing mortality risk. HIGHLIGHTS: A nationally representative, 10-year prospective cohort in China was employed to investigate the combined effects of lifestyle behaviors and cognitive function on all-cause, cardiovascular, and cerebrovascular mortality. Both healthy lifestyle and better cognitive function were associated with a reduced risk of all-cause mortality. Even among individuals practicing optimal lifestyle behaviors, cognitive impairment significantly elevated the risk of all-cause and cerebrovascular mortality. These findings underscore the necessity of incorporating routine cognitive assessments and targeted interventions with healthy lifestyle practices aimed at reducing mortality risk in aging populations.