<p>The arid northwest China (ANC), serving as an important part of the Silk Road Economic Belt and a typical ecologically fragile region, necessitates quantitative assessment and long-term prediction of ecosystem service value (ESV) along with exploration of the mechanisms driving its spatiotemporal evolution to support regional socioeconomic development and ecological security. The research applied the GDM and PLS-SEM to determine the dominant drivers of ESV dynamics and examine the interactions among factors. Additionally, this study estimated the ESV under different scenarios from 2020 to 2100. The results showed that farmland, forestland, and water areas contributed significantly to ESV growth. Land use intensity (LUI) (q = 0.473) emerged as the principal driver of spatial ESV differentiation, and two-factor interactions demonstrated substantially stronger explanatory power than individual factors. Geomorphic, vegetation, and LUI exerted direct positive effects on ESV, whereas socioeconomic and climatic factors showed direct negative effects; indirect pathways indicated that LUI amplified the positive effects of geomorphic and vegetation factors and intensified the negative climatic impacts. Scenario projections revealed a declining ESV trend from 2020 to 2100 across all scenarios, while pronounced losses of forest and grassland under the SSP2-4.5 scenario resulted in the largest. Therefore, it is recommended that ecosystem conservation and restoration efforts focus on forest and grassland ecosystems while actively addressing climate change, thereby promoting long-term regional sustainability and safeguarding ecological security in the ANC.</p>