Over the past decades, pronounced focus has been given to elucidating how ecosystem water use efficiency (WUE) responds to soil wetness and atmosphere humidity. Nonetheless, the intricate linkages between soil-atmosphere coupling dynamics and the global patterns of vegetation WUE remain elusive, particularly in the context of diverse CO2 emission trajectories anticipated toward the conclusion of the twenty-first century. The research delves into the change and features of the soil-atmosphere interplay, which is influenced by vapor pressure deficit (VPD) and soil moisture (SM). Furthermore, it examines the trends in vegetation WUE transitioning from a historical baseline spanning 1982 to 2014 to future forecasts encompassing 2015 through 2100, employing four distinct scenarios based on CMIP6 datasets. In addition, the study quantifies the effects of the coupled soil-atmospheric drought on WUE. The findings suggest a notable future rise in global mean vegetation WUE, with the SSP5-8.5 scenario showing the most rapid increase. Projections also suggest that a trend toward aridification in the worldwide soil and atmosphere conditions, particularly in regions such as the Amazonian basin, the Patagonian plateaus, as well as the Middle and Lower Valley of the Yangtze River, China. Among different scenarios, VPD is expected to stabilize after 2050 under the SSP1-2.6, reflecting the efficacy of proactive restoration strategies aimed at mitigating atmospheric drought. Meantime, more than 82.13% of vegetated territories demonstrates an inverse relationship between SM and VPD, indicating plant's heightened susceptibility to the intertwined dynamics of soil-atmospheric drought, particularly during warm seasons. About 47–59% of vegetated territories are characterized by the coupled VPD and SM across various climate scenarios, predominantly within the latitudinal range of 20° to 60°N and 20° to 40°S. Under moderate to high emission scenarios, the influence of SM and VPD coupling is anticipated to broaden, especially affecting arable land and grassland. As global temperatures escalate, regions situated at lower elevations are anticipated to experience heightened susceptibility to VPD, a phenomenon that may induce a pivotal transformation in the reliance patterns of temperate vegetation. Specifically, these ecosystems may transition from a dual reliance on SM and VPD to a sole dependency on SM, underscoring the need for a deeper understanding of such ecological adaptations.