High ozone (O₃) concentrations are frequently recorded in São Paulo Megacity, with extreme O₃ levels often linked to high temperatures and heatwaves, phenomena expected to intensify with climate change. The co-occurrence of extreme O₃ and heatwaves poses amplified risks to environmental and human health. Hence, this study aims to analyze individual and compound extreme O₃ and heatwave events and assess the associated atmospheric patterns. Hourly O₃ and temperature (T) data from 20 sites (1998–2023) were used to calculate the maximum daily 8 h average O₃ (MD8A-O₃) and maximum daily temperature (Tmax). The Mann–Kendall test identified trends for these variables. The 90th percentile of data from September to March defined thresholds for extreme events. Events were classified as extreme when MD8A-O₃ and Tmax exceeded their thresholds for at least six consecutive days. ERA5 data were used to evaluate atmospheric patterns during these events. The results show positive trends in MD8A-O₃ in 62% of sites, with values exceeding WHO Air Quality Guidelines, alongside positive Tmax trends in 90% of sites. Over the study period, four compound events, seven heatwaves, and four extreme O₃ events were identified. Compound and individual events were associated with the South America Subtropical Anticyclone and positive temperature anomalies. Individual O₃ events were linked to cold anomalies south of 30° S and positive geopotential height anomalies at 850 hPa. These findings highlight the increasing occurrence of extreme O₃ and heatwaves in São Paulo and their atmospheric drivers, offering insights to enhance awareness, forecasting, and policy responses to mitigate health and environmental impacts.