Sleep disturbance and executive dysfunction have been widely reported in children with autism spectrum disorder. While the positive impacts of physical activity on sleep quality and cognition are documented in children with typical development, similar studies in children with autism spectrum disorder are scarce. The objective of this study was to examine the impact of physical activity on sleep quality and cognition in children with autism spectrum disorder. A total of 40 children diagnosed with autism spectrum disorder (mean age = 9.95 years) were randomly assigned into two groups: physical activity intervention and control. Four sleep parameters (sleep efficiency, sleep onset latency, sleep duration, and wake after sleep onset) and two executive functions (inhibition control and working memory) were assessed. Results revealed a significant improvement in sleep efficiency, sleep onset latency, and sleep duration in the intervention group but not in the control group during weekdays. Moreover, a significant improvement in inhibitory control was shown in the intervention group but not in the control group. No significant improvement in working memory capacity was documented in either group (ps > 0.05). Our findings highlight the value of physical activity in improving sleep quality and cognition among children with autism spectrum disorder, but specific physical activity may be required to benefit individual executive functions.