Mounting evidence highlights the link between screen time and adolescent mood problems. However, there are several shortcomings to the extant literature: (1) this link is underexplored in preadolescents, (2) most existing studies look at mood problems using categorical diagnoses rather than from a symptom-level perspective, despite the heterogeneity within mood disorders, (3) few studies have simultaneously examined the links of mood symptoms with different types of screen time, and (4) family/child-level factors that have shown links to youth psychopathology are not typically considered. This study, for the first time, examined the relationships of mood symptoms with different types of screen time, while accounting for theoretically important factors-parental monitoring and the behavioral inhibition/activation systems (BIS/BAS)-in preadolescents aged 9 to 10 from 9986 families participating in the Adolescent Brain and Cognitive Development Study. Using mixed graphical models, we found that screen time involving age-inappropriate content was stably and significantly associated with various elevated mood symptoms, independent from other types of screen time, BIS/BAS, and parental monitoring. Additionally, age-inappropriate screen time was associated with increased overall symptom connectivity. Further, preadolescents engaged in high levels of age-inappropriate screen time reported different symptom profiles (i.e., differences in symptom centralities) from common pediatric mood problems. Our findings underline the multifaceted role (i.e., direct associations with symptoms, a moderator for symptom relationships, associations with distinct symptom profiles) of age-inappropriate screen time in preadolescent mood problems. These findings serve as foundations for future research that may facilitate early detection of preadolescents at risk of mood problems.