<p>Acceptance and Commitment Therapy (ACT) is a contextual intervention that targets psychological flexibility rather than symptom elimination. Its effectiveness for psychosis compared to active treatments is unclear. This study analysed the results of randomized controlled trials (RCTs) comparing ACT with active interventions for psychosis. Searches were conducted in PsycINFO, Scopus, and Web of Science up to February 2025 (PROSPERO ID: CRD420250653645<i>blinded</i>). Eligible studies compared ACT with active conditions and reported outcomes on social functioning, quality of life, rehospitalization rates, psychological flexibility, psychotic symptoms, and affective symptoms. Eleven RCTs (<i>N</i> = 606; 65.1% male) met the inclusion criteria. ACT showed consistent improvements in psychological flexibility, with additional evidence of benefits for negative and other psychotic symptom dimensions. Some studies also reported reductions in rehospitalization rates, while effects on social functioning and quality of life were limited and heterogeneous. Methodological quality was moderate. Overall, ACT appears promising for psychosis, particularly for improving psychological flexibility and reducing negative symptoms, although evidence remains preliminary and heterogeneous. Further randomized controlled trials are needed to assess its long-term effectiveness.</p>