Up to 80% of children with autism spectrum disorder (ASD) experience sleep disturbance. Poor sleep impairs executive functioning (EF), a lifelong difficulty in ASD. Evidence suggests EF difficulties in ASD are exacerbated by poor sleep. We examine whether early childhood sleep disturbances are associated with worsening EF trajectories in school-aged children with ASD. A subsample (n = 217) from the Pathways in ASD longitudinal study was analyzed. The Children’s Sleep Habits Questionnaire captured sleep duration, onset, and night awakenings before age 5 (mean = 3.5 years). Metacognition (MI) and Behavioral Regulation (BRI) indices, on the Teacher Behavior Rating Inventory of Executive Functioning, were used to measure cognitive and affective components of EF respectively at four time-points (7.8–11.8 years). We applied latent growth curve models to examine associations between sleep and EF, accounting for relevant covariates, including school-age sleep (mean = 6.7 years). Sleep traits had different age-related impacts on behavioral regulation, but not metacognition. Longer sleep onset at 3.5 years was associated with a worsening BRI difficulties slope (b = 2.07, p < 0.04), but conversely associated with lower BRI difficulties at 7.7 years (b = −4.14, p = 0.04). A longer sleep onset at 6.7 years was related to higher BRI difficulties at 7.7 years (b = 7.78, p < 0.01). Longer sleep duration at 6.7 years was associated with higher BRI difficulties at age 7.7 (b = 3.15, p = 0.01), but subscale analyses revealed shorter sleep duration at age 6.7 was linked to a worsening inhibition slope (b = −0.60, p = 0.01). Sleep onset is a robust early correlate of behavior regulation in children with ASD, whereas sleep duration is a later childhood correlate.