This study examined the relation of parental involvement with Korean adolescent academic achievement and self-efficacy, and the mediating role of academic self-efficacy in this relationship. We investigated the effects of parental involvement in both overall and domain-specific self-efficacy and academic achievement across three academic subjects (reading, English and mathematics). We conducted structural equation modelling analysis with the responses of 6,334 students from the Korean Education Longitudinal Survey. Our results were that first, academic self-efficacy partially mediated the relation between parental involvement and academic achievement. Specifically, domain-specific self-efficacy mediated the relations between parental involvement and academic achievement across three academic subjects (reading, English and mathematics), but these relations varied across subjects. Second, among multidimensions of parental involvement, parental participation and parental supervision had significant effects on adolescent academic achievement compared to parental expectation. This indicates that higher parental participation and parental supervision increased academic self-efficacy in Korean youth, which in turn, improved their academic achievement.