High levels of self-control are found to be associated with greater life satisfaction. To further understand this relationship, the current study examined two questions: (1) whether too much self-control reduces, rather than increases, life satisfaction, as argued by some scholars; and (2) whether engaging in prosocial behavior explains the "self-control-life satisfaction" link. To this end, we conducted survey research among adolescents (N = 1,009), university students (N = 2,620), and adult workers (N = 500). All participants answered the same self-control and life satisfaction measures, whereas prosocial behavior was assessed using different scales across samples. Results of two-line regressions failed to reveal significant inverted-U shaped association between self-control and life satisfaction across samples. Moreover, results of mediation analyses showed that across samples, high levels of self-control were related to greater life satisfaction and this association was partly mediated by prosocial behavior. In conclusion, there is no evidence showing that too much self-control impairs life satisfaction. Engaging in prosocial behavior partly explains how high self-control relates to greater well-being.