Abstract At present, the efficacy and safety of dexmedetomidine in patients receiving mechanical ventilation (MV) is still controversial. Therefore, the purpose of this research was to assess the efficacy and safety of dexmedetomidine in MV patients by reviewing the results of randomized controlled trials (RCT). RCTs evaluating the efficacy of dexmedetomidine in the treatment of MV patients were obtained by searching relevant online databases, including PubMed, EMbase, Web of Science, the Cochrane Library, Medline, OVID, and ClinicalTrials.gov. Literature meeting the inclusion criteria were selected and evaluated by two researchers independently. Risk ratio (RR)/standardized mean difference (SMD) and 95% confidence interval (CI) were used to express the differences between groups. Seven RCTs were included in our study, with 986 participants in the dexmedetomidine group and 862 participants in the control group. Summary analysis results displayed no reduction in 30‐day mortality (RR = 0.77, 95% CI: 0.59 to 1.02), delirium (RR = 0.77, 95% CI: 0.57 to 1.03), and adverse events (RR = 1.06, 95% CI: 0.22 to 5.08) in the dexmedetomidine group compared with the control group. As the length of stay in the intensive care unit (ICU) were presented as median and interquartile range (IQR)/standard deviation (SD), descriptive analysis of the results were performed. Generally, for 99.65% (953/986) of patients, dexmedetomidine was not better than the control group in reducing ICU length of stay. Our results demonstrate that for patients requiring MV, dexmedetomidine was not superior to the control group. However, analysis of more RCTs is required to confirm this conclusion.