Abstract: In the context of supporting Carbon Peaking and Carbon Neutrality Goals, studying the spatio-temporal characteristics of the synergistic effect of pollution and carbon emission reduction (SEPCER) and its influencing factors is crucial for formulating effective action plans. This research employs multiple spatial analysis models to examine the spatial and temporal patterns of the synergistic effect of pollution and carbon emission reduction across 91 cities in the Yellow River Basin from 2010 to 2022. Based on this analysis, key factors influencing the synergistic effect of pollution and carbon emission reduction were identified using geographic detector and spatial Durbin model. The study found that: (1) A decrease in average pollutant emission equivalents within the Yellow River Basin was observed. The average CO₂ emission showed an upward trend before 2021, but it decreased by 3.56% in 2022 compared with 2021. By 2022, the average synergistic effect of pollution and carbon emission reduction increased by 18.85% compared with 2010. The synergistic effect of pollution and carbon emission reduction exhibited the characteristics of spatial agglomeration, but its pattern changed over time, suggesting no lock-in effects. (2) Exploratory spatial-temporal data analysis (ESTDA) revealed that upstream cities had relatively unstable spatial structure compared to downstream and midstream cities. Strong intercity interactions were noted in the lower reaches, and weaker interactions in the middle reaches. Regarding spatial-temporal pattern transitions, 35.80% of the cities showed relatively stable patterns, reflecting strong spatial dynamics, with the overall network pattern dominated by positive correlations. (3) The synergistic effect of pollution and carbon emission reduction in the Yellow River Basin is primarily influenced by air circulation coefficient, energy consumption intensity, economic development levels, population density, trade openness, scientific research investment, and industrial structure upgrades. Among these factors, energy consumption intensity, economic development, and the air circulation coefficient are the most significant drivers, while trade openness has a positive spillover effect on spatial interactions. The interaction of these factors demonstrates a clear synergistic enhancement effect, underscoring the importance of multi-factor development strategies. This study indicates a gradual optimization trend in the synergistic effect of pollution and carbon emission reduction in the Yellow River Basin. We should focus on strengthening these key drivers, improving collaborative management systems, and addressing spatial disparities according to local conditions.