Objective Previous studies reported the effect of dexmedetomidine on intrathecal anesthesia. In this review, we explored the impact of dexmedetomidine as an adjunct for lumbar anesthesia in patients undergoing cesarean section. Methods Two authors searched eligible random controlled trials in electronic databases, including PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure, the Chinese BioMedical database, Chinese Scientific Journal Database, and the Wanfang database. Results Ten trials comprising 970 patients were included in this review. Intrathecal dexmedetomidine significantly reduced the onset time of sensory block (standardized mean difference (SMD), −1.50, 95% confidence interval (CI) −2.15, −0.85, I2 = 92%) and motor block (SMD −0.77, 95% CI −1.50, −0.49, I2 = 60%) and prolonged the block duration time (sensory block: SMD 2.02, 95% CI 1.29, 2.74, I2 = 93%; motor block: SMD 1.90, 95% CI 1.07, 2.74, I2 = 94%). Patients who received dexmedetomidine showed a lower incidence of shivering. No significant difference was reported for the neonatal Apgar score and other complications. Conclusion The use of intrathecal dexmedetomidine during cesarean section can shorten the onset time of spinal anesthesia and enhance the effect of local anesthetic. It has no significant impact on neonates and there were no other adverse events.