This study was a meta-analysis of randomized controlled trials (RCTs) of ranitidine as an adjunct for antipsychotic-induced weight gain in patients with schizophrenia. RCTs reporting weight gain or metabolic side effects in patients with schizophrenia were included. Case reports/series, non-randomized or observational studies, reviews, and meta-analyses were excluded. The primary outcome measures were body mass index (BMI) (kg/m2) and body weight (kg). Four RCTs with five study arms were identified and analyzed. Compared with the control group, adjunctive ranitidine was associated with marginally significant reductions in BMI and body weight. After removing an outlier study for BMI, the effect of ranitidine remained significant. Adjunctive ranitidine outperformed the placebo in the negative symptom score of the Positive and Negative Syndrome Scale. Although ranitidine was associated with less frequent drowsiness, other adverse events were similar between the two groups. Adjunctive ranitidine appears to be an effective and safe option for reducing antipsychotic-induced weight gain and improving negative symptoms in patients with schizophrenia. Larger RCTs are warranted to confirm these findings.