Socioeconomic vulnerability, defined as the susceptibility of communities to adverse environmental impacts based on exposure, sensitivity, and adaptive capacity, is a critical concern. This study quantifies the socioeconomic impacts of land degradation (soil erosion, desertification, and arable land loss) and climate change (temperature anomalies, precipitation variability, and extreme weather events) on vulnerable communities in China, with agricultural productivity, measured as crop yield per hectare, serving as a mediating pathway. Using multiple theoretical lenses and a robust econometric approach, the research tests the hypothesis that these environmental stressors interactively heighten vulnerability. Analyzing data from 2000 to 2021 across 31 Chinese provinces, results reveal that land degradation and climate change significantly increase socioeconomic vulnerability, with their combined effect amplifying impacts beyond their individual contributions, particularly in ecologically fragile regions like the Loess Plateau, where vulnerability is most pronounced. Agricultural productivity mediates this relationship, with yield declines amplifying vulnerability. The study recommends region-specific policies, such as strengthening the Grain for Green Program with socioeconomic safeguards, to mitigate these effects and support rural livelihoods.