This study examines how self-esteem and social support (parental, teacher, and peer) influence the career maturity of Korean adolescents over time. By synthesizing findings from 18 longitudinal studies, a meta-analysis was conducted. Results reveal that while self-esteem initially shows a strong correlation with career maturity, this relationship weakens significantly as adolescents age. In contrast, peer support maintains a relatively stable correlation with career maturity, even in late adolescence. Parental support also shows a gradual decline in its effect, but less sharply than self-esteem. Teacher support, though initially the weakest predictor, remains consistently correlated with career maturity throughout adolescence. These findings underscore the critical role of early self-esteem and social support in fostering career maturity and highlight the differing impacts of these factors over time.