Sleep problems are common in children with autism spectrum disorder. Although previous research has shown the positive effects of parent-based sleep intervention, it was mainly focused on face-to-face modality, which might limit accessibility. This study aimed to examine the efficacy of a telehealth-delivered parent-based sleep-focused intervention in treating insomnia in preschool children with autism spectrum disorder. A total of 62 parents/caregivers with a child with autism spectrum disorder and comorbid insomnia (aged 3-6 years) were randomized to receive either three weekly group sessions of sleep-focused intervention via Zoom with telephone support (n = 30) or treatment as usual (n = 32). The intervention group had significantly greater improvements in overall sleep problems (Children's Sleep Habit Questionnaire total score; p < 0.05), bedtime resistance (p < 0.05), and sleep-onset delay (p < 0.05) at post-treatment as compared to the treatment as usual group. The intervention group also showed significant improvements in overall behavioral and emotional problems (p < 0.05), especially externalizing problems (p < 0.05) as measured by Strengths and Difficulties Questionnaire, and parental stress level (p < 0.05) as measured by Depression, Anxiety and Stress Scale-21 as compared to the treatment as usual group (partial [eta][superscript 2] = 0.081-0.101). The findings supported the feasibility and promising effects of a brief parent-based sleep intervention delivered via telehealth.