ABSTRACT Background Metacognitive training (MCT) was developed in 2007 and widely used to modify the delusions for patient with schizophrenia. However, its effectiveness remains unclear. Aims To investigate the overall effectiveness of MCT for delusion in schizophrenia patients from 2007 to 2016, and to investigate the variables (intervention approach, intervention dose, and participant factors) of an MCT study that could influence the effect size. Methods Parallel‐arm design of MCT for delusions published from 2007 to 2016 were collected and then cross‐referenced using these keywords: delusion (psychosis or psychotic or schizophrenia) and metacognitive (training or therapy or intervention). The quality of the studies was evaluated and the effect size and the moderating variables of MCT on delusion were determined. Results A total of 11 studies on the effect of MCT for delusion were investigated. The MCT had a moderate immediate postintervention effect (g = −0.38) and a lasting effect after 6 months (g = −0.35). In terms of immediate effect, moderating variables with significant differences between them were (a) individual approach versus group‐based approach and mixed approach, and (b) eastern country versus western country. Linking Evidence to Action MCT could be used as a valuable nonpharmacologic intervention to reduce delusions in clinical settings. The individual modularized MCT approach had a beneficial effect and is recommended to healthcare professionals as an application for patients with schizophrenia or delusional disorder.