Internet gaming disorder (IGD) has become an important health concern in a significant proportion of adolescents. Intervention studies in this age group are scarce, mostly follow quantitative designs, and rarely consider adolescents’ experiences. This study aimed to evaluate the requirements for a group therapy program for adolescents with IGD. A qualitative interview study was conducted in a German clinic for addictive disorders in childhood and adolescence with nine participants (seven IGD patients (12–18 years, M = 15.86, SD = 1.95) and two psychotherapists). The semi-structured interviews addressed helpful contents, general conditions, and suggestions for alterations for an effective group intervention. Data were analyzed using content structuring qualitative analysis. Patient interview data resulted in 234 codings with eight main categories. Expert interview data yielded 151 codings with six main categories. The following treatment components were described as effective by the participants and experts: psychoeducation, emotion management, behavior analysis and modification, social skills training, parent participation, and relapse prevention. Additionally, adolescents emphasized the importance of group functionality for coherence, feedback and rewards, content presentation, physical activity and fun. The results are a valuable addition to findings from quantitative studies on IGD interventions and an interesting starting point for further representative studies.