This study investigated the dynamics and mechanisms between urban development and carbon emissions using the STIRPAT model. The IPCC calculation method and ridge regression were used to analyze panel data from Jiangxi Province spanning 2003 to 2021. The findings reveal that carbon emissions are positively influenced by per capita disposable income, outputs from the secondary and tertiary industries, urban population proportion, and built-up areas, with the secondary industry exhibiting the most substantial effect. In contrast, energy intensity demonstrates a negative relationship with carbon emissions, suggesting that improved energy intensity can reduce emissions. However, this reduction is insufficient to offset the carbon emissions generated by other urbanization factors. Additionally, an inverted U-shaped relationship between urbanization and carbon emissions was identified, indicating that a 1% increase in urbanization initially results in a 0.083% rise in carbon emissions, which subsequently declines after surpassing a specific threshold. These results underscore the necessity of promoting sustainable urbanization strategies to mitigate carbon emissions.