Background: Survivors of pediatric acute lymphoblastic leukemia (ALL) are at increased risk of neurocognitive weakness in the areas of attention, executive function, and processing speed. Although fatigue and sleep disturbances are frequent complications of ALL therapy and associated with cognitive functions, the impact of fatigue and sleep profiles during active ALL treatment on posttreatment neurocognitive performance has received limited attention. Methods: Pediatric patients (n = 120) with ALL (diagnosed 2011-2016) who completed fatigue and sleep questionnaires at four time points during active treatment were enrolled in a study of neurocognitive performance. Latent class growth analysis identified subgroups of patients with similar sleep and fatigue profiles during treatment. Neurocognitive performance collected >6 months post treatment on 40 participants was compared between latent classes using multivariable linear regression models. Results: Participants (57.5% male and 79.1% Hispanic or non-Hispanic White) were classified into one of two fatigue and sleep profiles: Class 1 characterized by mild fatigue and sleep disturbances during treatment (50.8%), and Class 2 characterized by higher levels of fatigue and sleep disturbances (49.2%). Posttreatment cognitive performance was in the normal range for most measures, but significantly below normative means for executive function, verbal short-term memory, attention, and distractability measures. Compared to Class 1, Class 2 demonstrated significantly (p < .05) poorer posttreatment neurocognitive performance, particularly in measures of attention. Conclusions: Our findings indicate that fatigue and sleep disturbances during the first year of pediatric ALL therapy may impact long-term neurocognitive performance.