Problems related to excessive use of the Internet and video games have recently captured the interests of both researchers and clinicians. The goals of this review are to summarize the literature on treatment effectiveness for these problems and to determine whether any treatments meet the minimum requirement of an evidence-based treatment as defined by Chambless et al. (1998). Studies of treatments for Internet gaming disorder (IGD) and Internet addiction were examined separately, as past studies have linked IGD to more severe outcomes. The systematic review identified 26 studies meeting predefined criteria; 13 focused on treatments for IGD and 13 on Internet addiction. The results highlighted a paucity of well-designed treatment outcome studies and limited evidence for the effectiveness of any treatment modality. Studies were limited by methodological flaws, including small sample sizes, lack of control groups, and little information on treatment adherence, among other problems. In addition, the field is beset by a lack of consistent definitions of and established instruments to measure IGD and Internet addiction. The results of this review highlight the need for additional work in the area of treatment development and evaluation for IGD and Internet addiction. Attention to methodological concerns identified within this review should improve subsequent research related to treating these conditions, and ultimately outcomes of patients suffering from them.