Aims <p>Soil dissolved organic matter (DOM) significantly contributes to the formation of soil organic carbon. However, how increasing aridity alters soil DOM dynamics and its key drivers remains poorly understood.</p> Methods <p>Accordingly, we established a sampling transect with varying aridity in the central region of the Loess Plateau, which encompassed six sites. Abandoned grasslands (~ 10&#xa0;years) on the sampling transect were selected as the study system, given their significant changes in soil DOM turnover. Analyzing the fundamental properties of vegetation and soil, we investigated the effects of aridity on variations in soil DOM by using spectroscopic techniques.</p> Results <p>Soil DOM sources were mainly characterized as biogenesis. Aridity significantly decreased soil carbon content as well as the aromaticity, hydrophobicity, average molecular weight, and humification degree of soil DOM (<i>P</i> &lt; 0.05). The fluorescence components of soil DOM were mainly humic-like substances, with maximum fluorescence intensity significantly decreasing with heightened aridity (<i>P</i> &lt; 0.05). The results of correlation analysis and variance partitioning analysis indicated that the aridity-driven variance in soil DOM was associated with plant, soil, and microbial properties.</p> Conclusions <p>Our study highlights that there are strong effects of plants, soil, and microorganisms in governing the variations in soil DOM characteristics under intensified aridity conditions. The findings offer theoretical foundations to enhance carbon sequestration and ecological management of abandoned grasslands.</p>