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Nitrogen dioxide (NO₂) significantly contributes to air pollution. Long-term NO₂ exposure is harmful to human health. The NO₂ pollution in China has surpassed developed countries and attracts international attention. To understand the spatial and temporal distributions of NO₂ across Chengdu in Southwest China, a random forest (RF) model was developed based on NO₂ environmental monitoring data, the Ozone Monitoring Instrument (OMI) satellite retrievals, and geographic covariates. The RF model showed good performance with a cross validation R² of 0.77, and a root mean square error (RMSE) of 11.0 μg/m³. The ground-level NO₂ concentrations of Chengdu for 2005–2016 were predicted using the developed model with the multiyear population weighted NO₂ concentration being 41.7 ± 11.7 μg/m³. The predicted NO₂ concentrations exhibited a clear seasonal variation trend with winter being the …