The purpose of this study was to ascertain how cognitive distortion could predict in-school adolescents' depressive symptoms and academic performance in the South-South Nigeria. The study adopted a correlation design with a sample of in-school adolescents who showed evidence of cognitive distortion (N = 798). In-School Adolescents' Cognitive Distortion Questionnaire (ISACDQ), In-School Adolescents' Depression Inventory (ISADI) and Academic Performance Scale (APS) were used for data collection while linear regression statistics procedure was adopted to analyse the data. Results show that cognitive distortion predicts in-school adolescents' depressive symptoms to a low degree while it predicts academic performance to a high degree. Based on the findings, conclusion, implication and limitations were drawn.