AimsSoil microorganisms are essential for regulating ecosystem functions, but their diversity, community structure and functions are influenced by aridity. The interactions among soil microorganisms, multifunctionality (MF) and aridity remain poorly understood.MethodsIn this study, we investigated bacterial and fungal community structure, co-occurrence networks, and assembly processes in rhizosphere and bulk soils under Caragana korshinskii plantations along an aridity gradient in arid and semiarid regions.ResultsThe results revealed that under different aridity gradients, deterministic and stochastic processes dominated the bacterial and fungal community assemblies, respectively. The bacterial community structure was more susceptible to the influence of soil properties than was the fungal community structure. With increasing aridity, the soil properties, MF, and microbial network complexity decreased significantly. The microbial keystone species, such as Alphaproteobacteria, Actinobacteria, Sordariomycetes, and Mortierellomycetes, had a great influence on mediating soil MF. This differential response between the rhizosphere and bulk soils decreased with increasing aridity. In addition, structural equation modeling suggested that aridity induced changes in soil moisture and pH and indirectly influenced soil MF by mediating fungal keystone taxa and bacterial network complexity and diversity, respectively.ConclusionThese results emphasize the role of complex interactions among microbes on mediating soil MF under arid conditions. Moreover, soil MF could be enhanced by regulating soil moisture and pH, thus driving changes in microbial communities in a particular direction under arid conditions.