(1) Background: There is increasing interest in the practice of mindfulness-based interventions (MBIs) to treat people with schizophrenia, as evidenced by the publication of different randomized controlled trials (RCTs). However, no meta-analysis of RCTs has been carried out to date with the exclusive inclusion of this type of interventions. (2) Objective: To analyze empirical evidence regarding the effectiveness of MBIs for the improvement of clinical parameters associated with schizophrenia. Method: A systematic review and meta-analysis was conducted of RCTs published in the databases PsycINFO, PubMed, WOS, and Cochrane Library. (3) Results: A total of 10 articles (n = 1094) fulfilled the criteria for inclusion in the review. The analysis of these studies suggests that MBIs combined with standard interventions are able to generate significant improvements in a variety of clinical schizophrenia-related parameters, such as the intensity of overall symptomatology (g = 0.72), positive symptoms (g = 0.32), negative symptoms (g = 0.40), functioning level (g = 1.28), and awareness of illness (g = 0.65). (4) Conclusions: There is evidence that supports the effectiveness and safety of MBIs for the treatment of people with schizophrenia. The results obtained by MBIs are comparable to those obtained by cognitive-behavioral therapy for psychosis. However, given the heterogeneity of the applied interventions and the methodological limitations found in the reviewed trials, the results should be interpreted with caution.