Transport development has often been regarded as a solution for increasing rural income. However, most existing studies focusing on the promotion effects of transport development on rural income fail to provide quantitative analysis of its influencing pathways. This study investigates the pathways linking county-level transport development to rural income in China. We first examined the spatial pattern of transport development, including density, proximity, and accessibility, in all Chinese counties from 2014 to 2019. Then, we analyzed both the association and influencing pathways between transport development and rural income using structural equation modeling (SEM). Finally, we compared the various effects and pathways among counties with different terrains, geographical locations, and poverty conditions through multigroup SEM analysis. The results suggest that transport development is associated with an increase in rural residents’ income primarily through the pathways of increasing nonfarm employment ratios, improving agricultural labor productivity efficiency, boosting urbanization rates, and enhancing access to basic public services. The most significant pathways through which transport development contributes to rural income growth in China are changes in nonfarm employment ratios and urbanization rates. The impact of transport development on rural incomes is more pronounced for counties in plain areas than counties in hilly and mountainous areas, more substantial in eastern counties than in central and western counties, and more pronounced in non-poverty-stricken counties than poverty-stricken ones. It is argued that transport alone cannot lead to significant rural revitalization in rural China; it must be accompanied by industrial development strategies.