<p>Internet addiction is of concern due to its high comorbidity with other mental health problems and its high prevalence in the general and clinical population. Due to this high prevalence, it is complicated for society to provide individualized and face-to-face psychological assistance to people addicted to the Internet, so Internet-based interventions are of great relevance to reach a large population in need of specific therapy for this problem. Several internet-based interventions for internet addiction have been developed in the last decade, although there is no meta-analysis study that analyzes the efficacy of these interventions exclusively. Therefore, the aim of this study was to conduct a systematic review and meta-analysis on the efficacy of internet-based psychological interventions to improve symptoms of internet addiction, anxiety and depression in patients with internet addiction. We selected randomized or non-randomized clinical trials with adult population with symptoms of internet addiction, treated with internet-based psychological interventions, providing a comparative group, and providing measures of internet addiction, anxiety or depression. The search was conducted in March 2024 in the SCOPUS, Web of Science, PsycINFO, PSICODOC, PsycARTICLES, Medline and Cochrane databases. Publication bias was assessed with Egger’s test, Hedges’ <i>g</i> effect size was calculated, and meta-regression analyses were performed. Eight studies were included in the meta-analysis, with 10 treatment groups and 8 comparative groups. Effect sizes were of moderate magnitude for internet addiction. Higher effect sizes were found when treatments were of longer duration, and incorporated goal-setting and social support-seeking components. Internet-based psychological treatments are a recommended option for the treatment of these symptoms in patients with internet addiction, although more studies are needed to provide more solid conclusions.</p>