Regular cannabis use during adolescence can have cognitive, psychological, and social consequences, leading to significant distress. Although psychological interventions are the primary treatment for cannabis use disorder, their efficacy in adolescents remains limited. This case study presents a comprehensive overview of a process-based conceptualization and treatment approach, Integrated Therapy for Adolescent Cannabis Misuse (ITACM), tailored for a young female patient with concurrent severe cannabis use and emotional symptoms. ITACM is an individual, brief intervention that includes family sessions, targeting emotion dysregulation and interpersonal difficulties, both of which have been empirically linked to cannabis use disorder in young people. The treatment integrates motivational interviewing, cognitive and behavioral therapy (including psychoeducation, promoting alternative behaviors, and relapse prevention) and an attachment-based therapy (addressing emotion regulation, relational processes, and promoting corrective attachment experiences). A thorough assessment of psychiatric symptoms and psychological processes was conducted at baseline, mid-intervention, post-intervention, and at a 2-month follow-up. At the end of the treatment, the patient reported a significant decrease in her cannabis use, anxiety, and depression, as well as improvements in emotion regulation strategies. The case study underscores significant outcomes following a 10-week course of psychotherapy addressing cannabis use, emotional dysregulation, and interpersonal difficulties in a young patient. The treatment protocol appears promising and warrants further investigation through a randomized controlled trial.