Background: Survivors of childhood acute lymphoblastic leukemia (ALL) are at increased risk for both treatment-related exercise intolerance and neurocognitive deficits. This analysis aimed to identify the association between exercise intolerance and neurocognitive impairments in ALL survivors. Methods: Cardiopulmonary exercise testing, results from a 2-hour standardized neuropsychological assessment, and self-report questionnaires were obtained for 341 adult survivors of childhood ALL and 288 controls. Multivariable modeling was used to test associations between oxygen uptake at 85% estimated heart rate (rpkVO2) and neuropsychological test and self-reported questionnaire domains, adjusted for sex, age at diagnosis, cranial radiation, anthracycline, and methotrexate exposure and tobacco smoking status. Results: Compared with controls, survivors had worse rpkVO2 and performance on verbal intelligence, focused attention, verbal fluency, working memory, dominant/nondominant motor speed, visual-motor speed, memory span, and reading and math measures (all P <.001). In adjusted models, exercise intolerance was associated with decreases in performance of verbal ability, focused attention, verbal fluency, working memory, dominant motor speed, nondominant motor speed, visual-motor speed, memory span, reading academics, and math academics in survivors. Conclusion: This study demonstrates an association between exercise intolerance and neurocognitive outcomes. Research is needed to determine whether interventions that improve exercise tolerance impact neurocognitive function in ALL survivors.