IntroductionUrbanization is a leading cause of global biodiversity loss, but its effects on soil microorganisms and biogeochemistry remain uncertain. Although urban soil microbiomes are influenced by common anthropogenic processes, generalizable patterns in how urbanization shapes their composition and functional potential are lacking. Identifying such patterns is essential for understanding cities’ roles in biogeochemical processes and managing continued urban expansion.MethodsWe re-analyzed soil metagenomic sequences from the Global Urban Soil Environment Ecology Network (GLUSEEN) to identify coordinated changes in microbial taxonomy and functional potential and to determine core taxa and metabolisms across five global cities spanning multiple ecoregions and management regimes.ResultsWe identified 111 gene annotations representing core urban soil functions that were present across all cities but rare in reference soils (<5% occurrence). Across gradients from low to high urban land use, nitrogen, trace and heavy metal, glycerol, and fructose/fructan metabolic processes were associated with more highly urbanized areas. Core urban microbial taxa, defined by their overrepresentation in urban land uses relative to reference soils, included diverse bacterial groups and a more constrained set of methane- and nitrogen-cycling archaea.DiscussionThese urban-associated taxonomic and functional signatures may serve as indicators of altered nutrient and contaminant cycling and provide a foundation for monitoring soil health and informing management strategies in rapidly urbanizing landscapes. More broadly, this work generates testable hypotheses and improves our ability to predict and manage how urban soils influence ecosystem services, contaminant dynamics, and global environmental change.