Abstract: Controlling ozone pollution is a crucial component of the pollution prevention initiatives outlined in China's 14th Five-Year Plan. This study utilized monitoring data (2015 to 2022) of near-surface nighttime O3during the warm seasons, and explored the spatial-temporal variations of the O3 concentrations across the Yangtze River Economic Belt (YREB), with a particular focus on the areas of the Yangtze River Delta, the middle reaches of the Yangtze River, and the Chengdu-Chongqing urban agglomerations. Furthermore, the exposure-response model was applied to evaluate the health risks associated with nighttime O3 exposure from 2015 to 2021. The results showed that: (1) The concentration of nighttime O3 during the warm seasons in the YREB exhibited a fluctuating upward trend, with an annual increasing rate of 0.81 μg簚(m3簚a)-1. Notably, the Yangtze River Delta urban agglomeration experienced the most significant annual increase in nighttime O3 concentration, at a rate of 17.6%. In contrast, the Chengdu-Chongqing and middle reaches of the Yangtze River urban agglomerations demonstrated more modest growth rates, with an increase of 8.3% and 7.8%, respectively. (2) The spatial distribution of nighttime O3 concentration in the YREB revealed a distinct pattern, with elevated levels observed in the northeast and reduced levels in the southwest. Additionally, the number of cities experiencing high nighttime O3 concentrations increased from 33 in 2015 to 44 in 2022. (3) The number of premature deaths that was attributed to nighttime O3 exposure peaked in 2018, and the number subsequently declined, and then experienced a rebound in 2021. By 2021, the mortality rate due to nighttime O3 exposure had decreased by 5% compared to that in 2015. Among the three urban agglomerations, the Yangtze River Delta exhibited the highest number of premature deaths from nighttime O3 exposure, followed by the Yangtze River Midstream city cluster, of which the Chengdu-Chongqing city cluster demonstrated the fewest. Deaths attributed to nighttime O3 exposure in the three urban agglomerations showed a downward trend. This study provided important references for future ozone pollution prevention and control, which was related to policy formulation and public health protection in the Yangtze River Economic Zone.