Internet Use Disorders (IUD) have a relevant effect on national economies. In the randomized, controlled, multicenter, prospective, and single-blinded OMPRIS study (pre-registration number DRKS00019925; Innovation Fund of the Joint Federal Committee of Germany, grant number 01VSF18043), a four-week online program to reduce media addiction symptoms, was evaluated for cost-effectiveness. The intervention group (IG) was compared to a waiting control group (WCG) from German statutory health insurance (SHI) and a societal perspective. Resource use, namely indirect and direct (non) medical costs, was assessed by a standardized questionnaire at baseline and after the intervention. Additionally, intervention costs were calculated. Determining the Reliable Change Index (RCI) based on the primary outcome, assessed by the “Scale for the Assessment of Internet and Computer Game Addiction” (AICA-S), individuals with and without reliable change (RC) were distinguished. The incremental cost-effectiveness ratio was calculated using the difference-in-difference approach. There were 169 (IG n = 81, WCG n = 88) persons included in the analysis. The mean age was 31.9 (SD 12.1) years. A total of 75.1% were male, and 1.8% diverse. A total of 65% (IG) and 27% (WCG) had an RC. The cost per person with RC was about EUR 860 (SHI) and EUR 1110 (society). The intervention leads to an improvement of media addiction symptoms at moderate additional costs.