Following the introduction of the 11th revision of the International Classification of Diseases (ICD-11), adolescents can now be diagnosed with a personality disorder based on severity ranging from mild to moderate to severe. This dimensional model has potential implications for treatment, as it allows clinicians and researchers to search for effective treatments targeting adolescents at different severity levels rather than offering all patients the same treatment. In this conceptual paper, we propose that the short-term mentalization-based therapy (MBT) program, originally developed to treat adults with borderline personality disorder (BPD), has potential clinical advantages for adolescents with ICD-11 personality disorder at the mild to moderate severity level. The short-term MBT program is a 5-month structured treatment approach including individual therapy, combined psychotherapy with the individual therapist also being one of the group therapists, and closed-group therapy to enhance cohesion and a feeling of security. The purpose of this paper is to make a case for the use of this format, as opposed to the traditional long-term MBT format, for adolescents with BPD. Future research should include large-scale randomized clinical trials powered to assess patient-important outcomes.