BACKGROUND: Maintaining cognitive health in old adults has become a significant public health challenge, with lung function and physical activity (PA) as essential modifiable factors. However, the joint and mediation effects of these two factors with cognition remain unclear. OBJECTIVES: This study assesses the joint association and mediation effects of lung function and PA with cognition. DESIGN, SETTING, AND PARTICIPANTS: We utilized cross-sectional data from the 2011-2012 U.S. National Health and Nutrition Examination Survey, including adults aged 60-79 assessed for lung function, PA, and cognition. MAIN OUTCOMES AND MEASURES: Lung function included forced expiratory volume in one second (FEV RESULTS: A total of 927 participants, representing 35,525,782 U.S. residents, were included, with a weighted median age of 65 (IQR, 63 -71) years, and 53.6 % were female. The results showed a significant positive association between lung function and cognitive function, with FEV CONCLUSION: Lung function and cognition may have a bidirectional relationship. The combination of active LTPA and better lung function was strongly associated with higher cognition, highlighting the need to strengthen exercise focused on lung function to maintain cognitive health in older adults.