Objectives: To examine the relationship between social support and aggression among male juvenile delinquents and the mediating role of mindfulness and self-control/impulsivity. Methods: A total of 530 male juvenile delinquents completed the Social Support Rating Scale, the Mindful Attention Awareness Scale, the Self-Control Scale, the Aggression Questionnaire, and the Barratt Impulsiveness Scale. Results: The total effect of social support on aggression was significant (beta= -0.24, p < 0.001, Bootstrap 95%CI[-0.38, -0.19]). Social support affected individual aggression through the following five paths: (1) social support -> trait mindfulness -> aggression (Bootstrap 95%CI[-0.07, -0.01]); (2) social support -> self-control -> aggression (Bootstrap 95%CI[-0.18, -0.08]); (3) social support -> impulsivity -> aggression (Bootstrap 95%CI[-0.12, -0.05]); (4) social support -> trait mindfulness -> self-control -> aggression (Bootstrap 95%CI[-0.07, -0.01]); (5) social support -> trait mindfulness -> impulsivity -> aggression (Bootstrap 95%CI[-0.03, -0.01]), indicating that these five mediating effects were significant. Conclusions: It suggests that social support is associated with aggression among male juvenile delinquents. Social support is negatively correlated with aggression through multiple mediating effects of mindfulness, self-control, and impulsivity.