We investigated whether participation in extracurricular sports promotes the life satisfaction of Chinese adolescents and tested the mediating effect of academic stress and the moderating effect of extraversion in this relationship. We conducted a survey with 1,608 Chinese adolescents to assess their participation in extracurricular sports and their levels of extraversion, academic stress, and life satisfaction. The regression analysis results indicate that extracurricular sports participation positively influenced life satisfaction through the mediator of academic stress. The moderated regression analysis results reveal that high extraversion strengthened not only the direct effects of extracurricular sports participation and academic stress but also the indirect effects of extracurricular sports participation and life satisfaction. These findings indicate that participation in extracurricular sports chiefly promoted life satisfaction in Chinese adolescents indirectly by reducing their academic stress, subject to the moderating effect of having an extraverted personality. Thus, increasing the time students spend on participating in extracurricular sports can help to enhance their life satisfaction.