Objectives: To explore the effect of health promotion program (HPP) on stress, quality of life, health-promoting lifestyles, and children’s attention-deficit/hyperactivity disorder (ADHD) symptoms in parents of children with ADHD. Methods: Sixty parents of children with ADHD were equally randomized into the intervention (health promotion program) and control (usual care) groups. Outcomes included parents’ stress, quality of life, health-promoting lifestyles, and children’s ADHD symptoms before, immediately after, and 1, 3, and 6 months after the intervention. The GEE was used to evaluate the effectiveness. Results: The intervention group reported significant improvement in the children’s hyperactivity/impulse and opposition at the 6- and 3-month, respectively. Parental overall stress significantly improved at 3 and 6 months. Parents’ quality of life had significant effects at the immediate, 3-month, and 6-month. Self-actualization behavior for health-promoting lifestyles had significant effects at the immediate follow-up. Conclusion: HPP can promote the mental well-being of parents of children with ADHD.