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Background Although an association between ozone (O 3) exposure and respiratory disease (RD) in children has been established, there is significant heterogeneity in global epidemiological evidence. The aim of this study was to fill a regional scientific gap by evaluating the impact of short-term O3 exposure on hospitalisations for RD among children in Foshan, a city in southern China.Methods This ecological time-series study used electronic medical records from a hospital in Foshan between 1 July 2021 and 30 June 2024, which included hospitalised children aged 0–14 years with a primary diagnosis of all RD classified according to the International Classification of Diseases 10th Revision (J00–J99). The distributed lag nonlinear model was applied to evaluate the association between O 3 exposure and RD in children.Results A total of 3944 hospitalisations for paediatric RD were enrolled, including 2218 boys (56.2%) and 1726 girls (43.8%). With the 2.5th percentile of O 3 concentration as the reference, a 10 μg/m3 increase in O3 was associated with a peak relative risk at lag days 6 and 7, with relative risk of 1.034 (lag day 6: 95% CI 1.014 to 1.054; lag day 7: 95% CI 1.016 to 1.051). Stratified analyses revealed no significant effect modification by season or sex in the association between O3 exposure and paediatric RD.Conclusion Short-term O 3 exposure significantly increased the risk of paediatric RD hospitalisations in Foshan. These results support the need for region-specific interventions to mitigate health risks from O3 in children.