Background When brain networks deviate from typical development, this is thought to contribute to varying forms of psychopathology. However, research has been limited by the reliance on discrete diagnostic categories that overlook the potential for psychological comorbidity and the dimensional nature of symptoms. Methods The present study examined the topology of functional networks in association with four bifactor-defined psychopathology dimensions—general psychopathology, internalizing symptoms, conduct problems, and attention-deficit/hyperactivity disorder (ADHD) symptoms—via the Child Behavioral Checklist in a sample of 3,568 children from the Adolescent Brain Cognitive DevelopmentSM Study (ABCD Study®). Local and global graph theory metrics were calculated at rest and during tasks of reward processing, inhibition, and working memory. Results Greater ADHD symptoms were associated with reduced modularity across rest and tasks, as well as reduced local efficiency in motor networks at rest. Results survive sensitivity analyses for medication and socioeconomic status. Greater conduct problem symptoms were associated with reduced modularity on working memory and reward processing tasks; however, these results did not persist after sensitivity analyses. General psychopathology and internalizing symptoms showed no significant network associations. Conclusions Our findings suggest reduced efficiency in topology in those with greater ADHD symptoms across four critical cognitive states, with conduct problems also showing network deficits, although less consistently. This may suggest modularity deficits are a neurobiological marker of externalizing behavior in youth. Such specificity has not been demonstrated before using graph theory metrics and has the potential to redefine our understanding of network deficits in children with psychopathology symptoms.