Metacognitive interventions have received increasing interest the last decade and there is a need to synthesize the evidence of these type of interventions. The current study is an updated systematic review and meta-analysis where we investigated the efficacy of metacognitive interventions for adults with psychiatric disorders. We included randomized controlled trials that investigated either metacognitive therapy (MCT; developed by Wells) or metacognitive training (MCTraining; developed by Moritz). Ovid MEDLINE, Embase OVID, and PsycINFO were searched for articles published until May 2024. The final analyses included 21 MCT- and 28 MCTraining studies (in total 3239 individuals). Results showed that MCT was more efficacious than both waiting-list control conditions (g = 1.84) as well as other forms of cognitive behavior therapies (g = 0.43). MCTraining was superior to treatment as usual (g = 0.45), other psychological treatments (g = 0.46) and placebo conditions (g = 0.15). Many of the included studies lacked data on blinding procedures, reporting of inter-rater reliability, treatment adherence, competence, treatment expectancy and pre-registration procedures. We conclude that both MCT and MCTraining are probably efficacious treatments but that future studies need to incorporate more quality aspects in their trial designs.