<p>Woody plant invasions are widely reported to modify ecosystem functioning, particularly through changes in soil nutrients and belowground processes, yet the direction and magnitude of these effects remain highly contrasting across species and environments. To address this gap, a PRISMA-compliant global meta-analysis of 117 studies encompassing 635 paired invaded–uninvaded comparisons was conducted to quantify changes in soil biochemical properties. Across studies, woody plant invasions were connected with increases in soil nitrogen (~ 50%), phosphorus (~ 34%), and organic carbon (~ 29%), while microbial biomass and enzyme activity showed no response. These effects were most pronounced in tropical, Mediterranean, and semi-arid regions, suggesting strong environmental modulation of invasion impacts. Trait-based analyses indicated that nitrogen-fixing species, deep-rooted plants, and arbuscular mycorrhizal associations were linked with greater soil nutrient accumulation, particularly in nutrient-poor and water-limited systems. Invasion intensity and duration further shaped outcomes, with stronger soil responses observed under high-intensity and early-stage invasions, whereas long-established invasions tended to show weaker effects, potentially reflecting long-term ecosystem adjustment. Thus, woody plant invasions are associated with context-dependent changes in soil biogeochemistry influenced primarily by plant functional traits and environmental conditions. These findings highlight the importance of integrating trait-based ecology with invasion stage and site context to expand belowground impacts prediction. Such an approach support targeted monitoring and restoration strategies, particularly in ecosystems most vulnerable to nutrient change under increasing woody plant encroachment.</p>