IntroductionAt‐risk youth are those who are currently or potentially exposed to physical, mental, or emotional danger. The Friendship Online Intervention Program (FOIP) was created to encourage physical activity (PA) and reduce risky behavior among vocational secondary‐school youth in Israel. We wanted to evaluate the effect of FOIP on PA, substance abuse, and psychological factors, including psychosomatic symptoms and well‐being.MethodsFrom October 2021 to June 2022, nonrandom sampling was employed to select at‐risk youth from vocational secondary schools for participation in the FOIP. Before and after the intervention, questionnaires were administered to the intervention and control groups. The effects of FOIP were evaluated by univariate and multivariable analyses.ResultsThe intervention (n = 103) and control (n = 77) groups showed similar levels of PA, cigarette smoking, and alcohol consumption at the beginning of the study. At follow‐up, the intervention group showed a 57% increase in PA versus no change for the control group and decreased levels of smoking compared to the control group (p < .001). Similarly, in the intervention group, the number of psychosomatic symptoms decreased (effect size = 1.68) and life satisfaction increased (effect size = 0.86). Group assignment (intervention or control group) significantly predicted PA level, cigarette smoking, psychosomatic symptoms, and life satisfaction (adjusted R2 = .46, .20, .08, and .28, respectively) with participants in the intervention group showing more favorable results compared with the control group.ConclusionsFOIP was effective in increasing PA and decreasing risky behaviors among youth. FOIP may help at‐risk youth build resilience and promote their physical and mental health.