<p>The combined effects of air pollution and extreme temperature events (ETEs) on physical function remain understudied. This study evaluated the individual and interactive associations of PM_2.5 mass, its constituents and ETEs with physical function in mid-to-older-aged Chinese adults. Utilizing 2011–2015 CHARLS data, this longitudinal analysis included 8834 observations from 4110 participants across 125 cities. Physical function (0 − 16 points) was assessed through physical tests of grip strength, balance, chair-rise capability, and walking speed. Linear mixed-effects models were used to investigate the associations of PM_2.5 constituents and ETEs with physical function, and bidirectionally stratified analyses were performed to testify the potential interaction between ETEs and PM_2.5 exposure. PM_2.5 mass and its components were consistently associated with poorer physical function. For each interquartile range rise, the greatest decline in physical function was − 0.481 (95% confidence interval: -0.552, -0.410) points for BC, followed by SO₄²⁻, OM, NH₄⁺, and NO₃^-. For per 10-day increase in ETEs duration per year under multiple definitions, physical function score was declined by 0.216 − 0.290 points for heat waves and 0.205 − 0.251 points for cold spells, respectively. Regional heterogeneity was observed in associations of physical function with PM_2.5 constituents and cold spells. We observed markedly intensified PM_2.5-related effects in the group of high-frequency cold spells only and intensified ETEs-related effects in high-pollution groups. These results suggested that prolonged PM_2.5 pollution and ETEs days were individually and interactively associated with impaired physical function in middle-aged and older adults, highlighting the importance for collaborative interventions amid climate change and aging.</p>