The study aimed to examine the longitudinal causal relationships of depressive moods, problematic mobile phone use, and negative school outcomes based on the cognitive-behavioral model among Korean adolescents. The changes within each construct over time were also explored. A total of 1,610 valid responses from three-year longitudinal data from the Korean Children and Youth Panel Survey were analysed and multivariate latent growth modeling was used. Depressive moods, problematic mobile phone use, and negative school outcomes at earlier ages each increased in severity across the three years. Initial levels of depressive moods increased initial levels of problematic mobile phone use and negative school outcomes, including changed rates of negative school outcomes. Additionally, changed rates of depressive moods positively predicted changed rates of problematic mobile phone use and negative school outcomes. Lastly, initial levels and changed rates of problematic mobile phone use predicted initial levels and changed rates of negative school outcomes respectively. Implications of the findings in the context of adolescents' psychological problems and problematic mobile phone use are discussed.