Purpose: We examined the mediating role of physical self-worth in the relationship between physical activity and quality of life in Korean adolescents. Methods: Data from 236 middle school students were used for the present study (boys = 139, 58.9%; girls = 97, 41.1%; middle school first grade = 127, 53.8%; middle school third grade = 109, 46.2%). Questionnaire data on demographics, physical activity, physical self-worth, subdimnesions of quality of life, and global quality of life were collected. We utilized the Hayes’ (2013) PROCESS Macro to test mediation models. Results: Results revealed that physical activity was associated with physical self-worth, which in turn, was associated with subdimensions of quality of life (e.g., physical, psychological, and emotion and moods quality of life) and global quality of life. Conclusion: More physical activity led to higher perceptions of physical self-worth, thereby contributing to higher perceptions of quality of life. Implications and directions for future research were discussed.