Objective The Attention Training Technique (ATT; Wells, 1990) is a brief metacognitive treatment strategy aimed at remediating self‐focused processing and increasing attention flexibility in psychological disorder. Method We systematically reviewed and examined the efficacy of ATT in clinical and nonclinical samples. Scientific databases were searched from 1990 to 2014 and 10 studies (total N = 295) met inclusion criteria. Single‐case data were meta‐analyzed using the improvement rate difference, and standardized between and within‐group effect sizes (ESs) were examined across 4 analogue randomized controlled trials (RCTs). Results Single‐case outcomes indicated that ATT yields large ES estimates (pooled ES range: 0.74–1.00) for anxiety and depressive disorders. Standardized ESs across the RCTs indicated that ATT yields greater treatment gains than reference groups across majority outcomes (adjusted Cohen's d range: 0.40–1.23). Conclusions These preliminary results suggest ATT may be effective in treating anxiety and depressive disorders and help remediate some symptoms of schizophrenia. Although a limited number of studies with small sample sizes warrants caution of interpretation, ATT appears promising and future studies will benefit from adequately powered RCTs.