Air pollutant gases emitted by anthropogenic activities significantly contribute to climate change and pose serious threats to human health. Among these pollutants, nitrogen dioxide (NO₂) and carbon monoxide (CO) are particularly significant contributors to urban air pollution. Satellite-based remote sensing has long been employed to monitor global air quality. This study aimed at investigating the temporal and spatial changes in average atmospheric NO₂ and CO concentrations in the Marmara Region of Türkiye during the summer (July–August) and winter (January–February) seasons between 2019 and 2024. For this purpose, we utilized high-resolution measurements from the recently launched Sentinel-5P TROPOMI sensor, which provides detailed insights into local air quality and pollution levels. Data processing was conducted using Google Earth Engine (GEE), and spatial distribution patterns were mapped in ArcGIS Pro. Within this framework, the study was structured around the following key research question: “How have NO₂ and CO concentrations changed seasonally and annually before and after the COVID-19 outbreak?” The findings revealed that NO₂ and CO concentrations exhibited seasonal fluctuations throughout the study period, with significant increases and decreases at specific intervals. Notably, a sharp decline in these pollutant levels was observed during the COVID-19 pandemic in 2020, whereas a considerable rebound has been detected in certain regions since 2021. Moreover, NO₂ and CO concentrations were found to be significantly higher in cities characterized by high population density and intensive industrial activities, such as Istanbul, Bursa, and Kocaeli. These findings offer critical insights into the spatiotemporal changes in NO₂ and CO emissions, underscoring the effectiveness of Sentinel-5P satellite data as a powerful tool for air quality monitoring. This study serves as a roadmap for policymakers by supporting policy development processes in cities striving to enhance air quality and ensure sustainable air pollution management through comprehensive spatial analyses of NO₂ and CO concentrations.