PurposeA recent increase in screen time during early childhood has adversely affected the sleep and psychosocial health of children; however, limited information is available regarding effective interventions to reduce the screen time among them. This study aimed to investigate the effect of a parental educational program on screen use, sleep quality, and psychosocial adaptation among preschoolers. Design and methodsA clustered randomized controlled study with a parallel-group design was conducted. Preschoolers with a screen time of ≥2 h/day and their parents were recruited. In total, 14 kindergartens containing 129 parent–child dyads were randomly allocated to either the experimental group (receiving parental education, N = 63 dyads) or the control group (daily activities, N = 66 dyads). Data were collected before and after the intervention. A screen time questionnaire, the Children's Sleep Habits Questionnaire, and the Pediatric Symptom checklist-17 were provided to the participants. A linear mixed-model analysis was performed to examine the efficacy of the intervention. ResultsAfter the intervention, the screen time of children in the experimental group was significantly reduced (effect size: 0.83, p < .001), and they presented improved sleep quality (effect size: 0.57, p = .01) and attention score (effect size: 0.77, p = .02) for psychosocial adaptation. ConclusionsParental education is an effective intervention for reducing screen time and improving sleep quality and attention among preschoolers. Practice implicationsHealthcare professionals should consider implementing parental educational programs to reduce screen time, and thus improve the sleep quality and psychosocial health of preschoolers.