The mismatch between financial objective and subjective knowledge that occurs in youth and adolescents has been understudied in the literature. Based on objective and subjective financial literacy scores, this study categorizes financial literacy into four types: financial literacy overconfidence, underconfidence, competence, and naïvete in a sample of adolescents. Data were collected from 330 students aged around 15 years old in six middle schools in Hong Kong. The results indicate that adolescents who are overconfident about their financial literacy are more likely to engage in risky financial behavior and report higher levels of financial autonomy. A randomized experimental trial was conducted to assess whether financial education could change the mismatch between financial objective and subjective knowledge. The results show a significant increase in underconfidence after the financial education intervention, but no significant change in the other three categories. The findings highlight the same type of financial literacy overconfidence in both adolescents and adults and has implications for financial counselors and educators who would improve the financial engagement of adolescents.