Acute kidney injury (AKI) is a common complication after cardiac surgery in adults and increases morbidity and mortality. This updated systematic review and meta-analysis of 16 randomized controlled trials (n=2882 patients) evaluated the effect of perioperative dexmedetomidine (DEX) on renal outcomes. DEX significantly reduced the incidence of AKI [RR 0.58; 95% CI 0.37–0.91; I²=74%; p=0.02], especially at doses of 0.6–0.1 μg/kg/h [RR 0.43; 95% CI 0.26–0.71; I²=0%; p=0.001], while a dose of 0.4 μg/kg/h did not produce a significant effect [RR 0.65; 95% CI 0.36–1.17; I²=84%; p=0.15]. DEX shortened ICU stay [MD −1.23; 95% CI −2.17 to −0.30; I²=93%; p=0.01], duration of mechanical ventilation [MD −1.24; 95% CI −2.15 to −0.33; I²=97%; p=0.008] and total hospital stay [MD −0.33; 95% CI −0.54 to −0.13; I²=86%; p=0.01]. It did not affect mortality or perioperative times. The conclusion indicates renal protection of DEX and improvement of postoperative recovery, with the need for further investigation of optimal doses.