Objectives To review the effectiveness of psychological therapies for adolescents with borderline personality disorder (BPD) or BPD features. Methods We included randomized clinical trials on psychological therapies for adolescents with BPD and BPD features. Data were extracted and assessed for quality according to Cochrane guidelines, and summarized as mean difference (MD) with 95% confidence intervals (CI) for continuous data and as Odds ratios (OR) with 95% CI for dichotomous data. Risk of bias was assessed using Cochrane’s risk of bias tool for each domain. When possible, we pooled trials into meta-analyses, and used Trial Sequential Analysis (TSA) to control for random errors. Quality of the evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE). Results 10 trials on adolescents with BPD or BPD features were included. All trials were considered at high risk of bias, and the quality of the evidence was rated as “very low”. We did TSA on the primary outcome and found that the required information size was reached. The risk of random error was thus discarded. Conclusion Only 10 trials have been conducted on adolescents with BPD or BPD features. Of these only few showed superior outcomes of the experimental intervention compared to the control intervention. No adverse effects of the interventions were mentioned. Attrition rates varied from 15–75% in experimental interventions. The overall quality was very low due to high risk of bias, imprecision and inconsistency, which limits the confidence in effect estimates. Due to the high risk of bias, high attrition rates and underpowered studies in this area, it is difficult to derive any conclusions on the efficacy of psychological therapies for BPD in adolescence. There is a need for more high quality trials with larger samples to identify effective psychological therapies for this specific age group with BPD or BPD features.