Individual differences in children’s cognitive abilities have significant consequences for life and health outcomes. What factors influence individual differences in cognitive performance during development? Here we test the hypothesis that children’s environments predict their cognitive performance, independent of well-characterized effects of socioeconomic status. To this end, we analyzed data from 9,002 9-10-year-olds from the Adolescent Brain Cognitive Development (ABCD) Study, an ongoing longitudinal study with community samples across the United States. Using data from youth- and caregiver-report questionnaires and national database registries (e.g., neighborhood crime and walkability), we defined principal components summarizing children’s home, school, neighborhood, and cultural environments. Across two independent ABCD data releases (n = 3,475 and 5,527), sociodemographics and environmental components explained unique variance in children’s general cognitive ability, executive functioning, and learning/memory abilities. In addition, there was a significant interaction between sociodemographics and neighborhood environments in explaining variance in general cognitive abilities, such that increased neighborhood enrichment decreased the relationship between sociodemographics and general cognition. Thus, aspects of the physical and social environment predict unique variance in cognitive performance during development and should be considered in addition to sociodemographic factors to understand brain functioning and behavior.