The purpose of this study was to investigate the mediating effects of career-related parental support on the relationship between family leisure activities and career maturity of adolescents. Data from 332 students of 3 middle schools and 3 high schools in Gwangju and Yongin in Gyeonggi province were analyzed. The measures used were the family leisure scale reconstructed by Lee Min-ah(2006), the career maturity scale reconstructed by Lee, Ki Hak & Han, Jong Chul(1997), and the career-related parent support scale developed by Turner et al.(2003). Descriptive statistics, t-test, correlation analysis, and structural equation modeling were performed using SPSS 22.0 and AMOS 22.0. The bootstrap method was used to test the mediating effect. The main results were as follows. First, family leisure activities showed higher participation by middle school students than high school students. The perceived level of career-related parental support was higher among high school students than middle school students, and the higher the level of household income was, the higher career-related parental support was. Career maturity was higher among high school students than middle school students. Finally, the relationship between family leisure activities and career maturity is mediated by career-related parental support. The more family leisure activities were, the higher the perceived career-related parental support was. The higher the perceived career-related parental support was, the higher the career maturity was. The results suggested family leisure activities as another important way to enhance the career maturity of adolescents. This study provided some valuable implications for career-related educational and counseling services for adolescents and their families.