To describe the association between neighborhood opportunity measured by the Child Opportunity Index 2.0 (COI) and patterns of hospital admissions and disease severity among children admitted to US pediatric hospitals.Retrospective, cross-sectional study of 773 743 encounters for children <18 years of age admitted to US children's hospitals participating in the Pediatric Health Information System database 7/2020-12/2021.The proportion of children from each COI quintile was inversely related to the degree of neighborhood opportunity. The difference between the proportion of patients from Very Low COI and Very High COI ranged from +32.0% (type 2 diabetes mellitus with complications) to -14.1% (mood disorders). The most common principal diagnoses were acute bronchiolitis, respiratory failure/insufficiency, chemotherapy, and asthma. Of the 45 diagnoses which occurred in ≥0.5% of the cohort, 22, including type 2 diabetes mellitus, asthma, and sleep apnea had higher odds of occurring in lower COI tiers in multivariable analysis. Ten diagnoses, including mood disorders, neutropenia, and suicide and intentional self-inflicted injury had lower odds of occurring in the lower COI tiers. The proportion of patients needing critical care and who died increased, as neighborhood opportunity decreased.Pediatric hospital admission diagnoses and severity of illness are disproportionately distributed across the range of neighborhood opportunity, and these differences persist after adjustment for factors including race/ethnicity and payor status, suggesting that these patterns in admissions reflect disparities in neighborhood resources and differential access to care.