Background: Electroconvulsive therapy (ECT) has been widely used in treating older adult patients with major depressive disorder. The results of randomized controlled trials (RCT) are mixed. This study systematically examined the efficacy and safety of ECT versus antidepressants (AD) in older adult patients with major depressive disorder. Methods: A literature search was conducted independently by two reviewers using the PubMed, Embase, PsycINFO, Cochrane Library, Chinese National Knowledge Infrastructure, Wanfang, and SinoMed databases from their inceptions until 17 May 2017. The Cochrane risk of bias and Jadad scale were used to assess the quality of RCT included in the systematic review. Results: Five RCT (n = 374; mean age: 66.0–66.4 years; men: 36.4–58.3%) all conducted in China were identified, including three RCT (n = 203) with ECT alone and two RCT (n = 171) with ECT-AD co-treatment. In two of the three RCT, ECT alone was superior to AD monotherapy in improving depressive symptoms as assessed by the Hamilton Depression Scale and by clinical judgement at the conclusion of the course of ECT. Both RCT of AD-ECT co-treatment showed a significant reduction in the Hamilton Depression Scale total score after ECT compared with AD monotherapy. The response rate ranged from 80% to 97.5% in the ECT groups and from 63.4% to 73.3% in the AD groups. Rates of adverse reactions were similar between ECT and AD groups in studies with available data. Only one RCT reported the discontinuation rate without a significant group difference. Conclusions: This systematic review showed that ECT appears to be an effective and safe treatment for older adult patients with major depressive disorder. Further high-quality studies with extended follow-up are warranted.