This study examined the effects of multidimensional perfectionism (i.e., adaptive and maladaptive functions of perfectionism) on adolescents’ school adjustment. For this purpose, this study utilized a mediation model that incorporates a self-directed learning strategy as a key model variable. Two hundred ninety-three students in South Korea completed a demographic questionnaire, the Frost Multidimensional Perfectionism Scale, the Self-Directed Learning Strategies Scale, and the School Adjustment Scale. Correlational analyses and a multiple regression analysis were run to investigate the relationships among the three variables, as well as the mediating role of self-directed learning strategies on school adjustment. While the adaptive functions of perfectionism were significantly correlated with self-directed learning strategies, the maladaptive functions of perfectionism demonstrated no significant results. Moreover, self-directed learning strategies were found to be a significant mediating factor in the relationship between the adaptive functions of perfectionism, namely organization, and school adjustment. More specifically, adaptive functions of perfectionism was positively associated with self-directed learning strategy, which in turn, was positively associated with greater school adjustment. These findings signify the importance to address both multidimensional perfectionism and self-directed learning strategies in school adjustment.