<p>The role of psychosocial stress as a factor in both the development of psychosis and the exacerbation of acute psychotic episodes is increasingly well understood. Various approaches to stress reduction have been shown to be helpful for psychosis patients, but they are rarely included in guidelines and treatment algorithms. In this systematic review and meta-analysis, we examined the effectiveness and potential adverse effects of interventions that specifically aim to reduce stress in psychosis patients. To do so, we systematically searched five databases (PubMed, Scopus, Web of Science, PsycINFO, Cochrane-Library) for studies on relaxation interventions in psychosis treatment. Of the identified studies, 24 (<i>N</i> = 1292 patients) were eligible for inclusion. We performed a systematic review and general meta-analysis and a subgroup analysis for patient setting (inpatient, outpatient, rehabilitative, or mixed). The general analysis showed small to moderate effects of the interventions on general, positive, and negative symptoms but not for the reduction of stress. In the subgroup analysis, psychosis patients in outpatient and rehabilitative settings benefitted more from the interventions than those in an inpatient setting. No adverse effects were reported. These results help to consider the integration of relaxation techniques for stress reduction as an add-on therapy in psychosis treatment.</p>