Chronic kidney disease (CKD) has become a common health problem among middle-aged and elderly people in China. The aim of this study was to investigate the effects of physical activity on renal function in Chinese middle-aged and elderly people.Nationwide cohort study.3599 participants in the 2011 China Health and Aging Longitudinal Study (CHARLS) were used in the cross-sectional study, with estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m2 as the endpoint event. 2309 participants in the 2015 CHARLS were used in the longitudinal study, with eGFR <60 ml/min/1.73 m2 or ≥25 % decrease in eGFR as the endpoint events. 2190 participants from the longitudinal study, after excluding those with baseline eGFR < 60 ml/min/1.73m2, were included in a sensitivity analysis to reassess the associations. Physical activity intensity was assessed by self-report. Associations between physical activity levels and renal function were analyzed using logistic regression.In cross-sectional analyses, engaging in moderate (MPA) or vigorousphysical activity (VPA) for more than 300 min/week was associated with a significantly lower likelihood of renal endpoint events compared to physically inactive participants (OR = 0.39, 95 % CI: 0.30-0.51). After correction for clinical characteristics and blood test results, VPA and MPA >300 min/week remained independent protective factors for renal function. In the longitudinal cohort, VPA and MPA >300 min/w reduced the risk of renal endpoint events by 45 % (OR = 0.55, 95 % CI = 0.38-0.80). After correcting for clinical characteristics and blood test results, VPA and MPA >300min/w still reduced the risk of renal endpoint events by 37 % (OR = 0.63, 95 % CI = 0.43-0.92) and 39 % (OR = 0.61, 95 % CI: 0.42-0.89), respectively. Sensitivity analysis further confirmed the robustness of these findings, with VPA and MPA > 300 min/week consistently identified as independent protective factors.Physical activity is associated with a reduced risk and delayed onset of renal insufficiency. The results of this study provide additional evidence for the renoprotective effects of exercise in non-CKD populations.Copyright © 2025 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.