Abstract Objective Pediatric brain tumor (PBT) survivors are at high risk for cognitive and adaptive challenges. We aimed to examine the relationship between executive functioning (EF) and adaptive functioning in PBT survivors to identify critical cognitive skills that are associated with functional impact to inform intervention and transition to adulthood. Method Retrospective neuropsychological data was collected for 95 clinically referred PBT survivors (8–24 years). A composite EF measure was created based on the average of selected EF subtest scores. The associations between EF skills, parent-report of child adaptive functioning, and full-scale IQ were analyzed using descriptive statistics, correlations, and multiple regression. Results Adaptive functioning was significantly related to parent (r = −0.701, p < 0.001) and teacher ratings (r = −0.372, p = 0.004) of EF, the testing composite measure of EF (r = 0.455, p = 0.033), as well as FSIQ (r = 0.386, p < 0.001), general cognitive ability (r = 0.328, p = 0.003), working memory (r = 0.279, p = 0.007), and processing speed (r = 0.425, p < 0.001). Parent reports of EF were not significantly related to the EF testing composite score, but both significantly predicted adaptive functioning (p < 0.001). Of parent-reported domains of EF, self-monitoring was most predictive of overall adaptive functioning (B = −0.415, p = 0.017). FSIQ and age did not impact the relationship between parent reports of EF and adaptive functioning. Conclusions Overall, EF on both parent reports and testing, especially self-monitoring, was predictive of adaptive functioning in PBT survivors, regardless of age and overall intellectual functioning. Future research should further examine the impact of individual and treatment factors.