Individuals with autism spectrum disorder (ASD) demonstrate challenges with executive function (EF), adaptive behavior, and mental health, all of which place long‐term wellbeing at risk. In the current study we examined the relation between parent‐rated EF and adaptive functioning and internalizing symptoms (anxiety, depression), as we expected that identifying the specific EF domains most closely related to these indices of functioning would illuminate opportunities for targeted intervention. Participants included 59 children and adolescents with ASD (M = 10.1 years) and 67 who were typically developing (TD) (M = 9.4 years) matched on age, IQ, mental age, and maternal education. Caregivers completed the Behavior Rating Inventory of EF (BRIEF) and Behavior Assessment System for Children, Second Edition (BASC‐2). Parents rated children with ASD as demonstrating significantly more challenges across most of the examined BRIEF and BASC‐2 indices and scales, with the exception of organization of materials (BRIEF) and anxiety (BASC‐2). For both groups, metacognitive EF processes emerged as strongly associated with practical, conceptual, and social skills, though different BRIEF scales emerged as significant across the component subdomains. In terms of the relation with mental health, BRIEF index scores were unrelated to anxiety for both groups. Behavior regulation, however, was significantly associated with depression symptoms for children with and without ASD. The findings highlight the possibility that targeting particular EF domains among individuals with and without ASD may not only have direct benefit for behavior regulation and metacognitive abilities, but may also extend to other areas of life, including adaptive behavior and concomitant internalizing symptomatology. Autism Res 2017. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. Lay Summary We examined whether parents' ratings of their children's flexibility and ability to monitor their behavior predicted adaptive skills (e.g., ability to complete day‐to‐day personal tasks, communicate, and socialize) and symptoms of anxiety and depression among children with and without autism spectrum disorder. For both groups, children's abilities to manage and monitor their behavior were strongly related to adaptive skills. Children's flexibility and ability to inhibit inappropriate behavior and control their emotions was associated with depression symptoms for both groups.