The present study investigated the mediating role of career adaptability in the relationship between youth-perceived contextual support and positive youth development on the basis of a survey of 1,047 students in 10th to 12th grades. Measurement model analysis revealed that career search self-efficacy (CSSE), goal capacity, academic self-efficacy, and intrinsic motivation all fit within a latent construct representing career adaptability. Subsequently, structural model analysis revealed that career adaptability fully mediates the relationship between contextual factors and positive youth development. In addition, these analyses identified eight specific indirect pathways: CSSE and goal capacity fully mediated the relationship between quality learning experience/social connection and decision-making readiness; CSSE and academic self-efficacy partially mediated the relationship between social connection and stress management, and they also acted as suppressor in the relationship between quality learning experiences and stress management. These findings establish notable implications for career counseling and intervention practices that are discussed in closing.