Depression is a major problem in youth mental health and identified as the leading cause of disability worldwide. There is ample research on the acute effects of treatment, with estimated small-to-moderate effect sizes. However, there is a lack of research on long-term outcomes. A total of 129 adolescents with clinical depression (82.2% female), aged 13–22 (M = 16.60, SD = 2.03), received blended CBT, face-to-face CBT or treatment as usual. Data were collected at 12 months after the intervention and compared between treatment conditions. Clinical diagnosis, depressive symptoms, suicide risk, internalizing symptoms and externalizing symptoms decreased significantly over time, from baseline to the 12-month follow-up, and also from post-treatment to the 12-month follow-up in all three conditions. Changes were not significantly different between conditions. At the long-term, improvements following the treatment continued. Due to the large amount of missing data and use of history control condition, our findings need to be interpreted with caution. However, we consider these findings as a clinical imperative. More evidence might contribute to convincing adolescents to start with therapy, knowing it has lasting effects. Further, especially for adolescents for whom it is not possible to receive face-to-face treatment, blended treatment might be a valuable alternative. Our findings might contribute to the implementation of blended CBT.