This systematic review aimed to evaluate the effects of aquatic exercise on physical performance in older adults. Databases were searched up to July 2021. Randomized controlled trials were screened by two reviewers, who extracted data and assessed study quality. Ten randomized controlled trials (603 participants) were included. Compared with nonexercising controls, aquatic exercise probably improved lower limb muscle power (30-s Chair Stand Test; mean difference 4.75 repetitions; 95% confidence interval [0.07, 9.42]; I2 = 99%; 251 participants; very low-quality evidence). When comparing aquatic exercise with land exercise, there is probably no superiority in favor of either intervention on dynamic balance (Timed Up and Go Test; mean difference −0.12 s; 95% confidence interval [−0.37, 0.12]; I2 = 3%; 244 participants; very low-quality evidence).