This meta-analysis systematically reviewed the evidence on standardized acceptance-/mindfulnessbased interventions in DSM-5 anxiety disorders. Randomized controlled trials examining Acceptance and Commitment Therapy (ACT), Mindfulness-Based Cognitive Therapy (MBCT), and Mindfulness-Based Stress Reduction (MBSR) were searched via PubMed, Central, PsycInfo, and Scopus until June 2021. Standardized mean diferences (SMD) and 95% confdence intervals (CI) were calculated for primary outcomes (anxiety) and secondary ones (depression and quality of life). Risk of bias was assessed using the Cochrane tool. We found 23 studies, mostly of unclear risk of bias, including 1815 adults with diferent DSM-5 anxiety disorders. ACT, MBCT and MBSR led to short-term efects on clinicianand patient-rated anxiety in addition to treatment as usual (TAU) versus TAU alone. In comparison to Cognitive Behavioral Therapy (CBT), ACT and MBCT showed comparable efects on both anxiety outcomes, while MBSR showed signifcantly lower efects. Analyses up to 6 and 12 months did not reveal signifcant diferences compared to TAU or CBT. Efects on depression and quality of life showed similar trends. Statistical heterogeneity was moderate to considerable. Adverse events were reported insufciently. The evidence suggests short-term anxiolytic efects of acceptance- and mindfulnessbased interventions. Specifc treatment efects exceeding those of placebo mechanisms remain unclear. Protocol registry: Registered at Prospero on November 3rd, 2017 (CRD42017076810).