The metacognitive model of post-traumatic stress disorder (PTSD) proposes that the natural emotional processing following a traumatic event may be impaired due to the negative effects (thoughts and emotions) related to the trauma and its memory. Metacognitive Therapy (MCT) is increasingly being used as a treatment for PTSD. This meta-analysis aimed to examine the effectiveness of MCT clinical outcomes in treating PTSD over the past two decades. In this meta-analysis, we analyzed experimental studies published between January 2000 and October 2022, in which MCT was administered to young and adult patients with PTSD. We searched databases including ERIC, ETHOS, Google Scholar, Medline, ProQuest, PsycNet, PubMed, and Web of Science. Overall, seven studies examining PTSD met our eligibility criteria; all seven utilized pre- and post-treatment measurements. We identified only one study conducted with children and adolescents (ages 10–19). Within the scope of the meta-analysis, effect size and heterogeneity were analyzed, and publication bias was assessed. We found that the comparison of pre- and post-treatment resulted in a large effect size (Hedges’ g=2.878), indicating that MCT is an effective treatment for PTSD. The significance of the Q statistic suggests heterogeneity. Our analysis indicates an absence of publication bias. The current study’s pre- and post-treatment effect size estimates suggest that MCT is effective in reducing PTSD symptoms, indicating that MCT can be a superior treatment for PTSD. However, further randomized controlled trials and cross-cultural studies with larger participant pools are necessary to reach more definitive conclusions.