Childhood obesity prevalence rates in the United States are the highest in the rural Appalachian areas. Teens mentoring younger children to reverse obesity health risks are an understudied approach. This randomized-controlled trial compared the effects of two curriculum delivery methods and assessed the mediating effects of the number of sessions attended on the outcomes. The control group received the 8-week Just for Kids! curriculum via an adult teacher in a classroom and the experimental group received the same curriculum via individual teen mentoring. Data collected at baseline and postintervention were analyzed using multilevel linear models. Each of the outcomes (e.g., body mass index, blood pressure, current lifestyle behaviors) were modeled separately. Only the mentored children demonstrated improved current lifestyle behaviors (e.g., physical activity and dietary patterns) and health outcomes. Teen mentoring was an effective and efficacious approach to impact the lifestyle patterns and health outcomes of children in a school setting.