Background The effects of neuromuscular blocking agents (NMBAs) on adult patients with acute respiratory distress syndrome (ARDS) remain unclear. We performed a meta-analysis of randomized controlled trials (RCTs) to evaluate its effect on mortality. Methods We searched the Cochrane (Central) database, Medline, Embase, the Chinese Biomedical Literature Database (SinoMed), WanFang data and ClinicalTrials from inception to June 2019, with language restriction to English and Chinese. We included published RCTs and eligible clinical trials from ClinicalTrials.gov that compared NMBAs with placebo or usual treatment in adults with ARDS. We pooled data using random-effects models. The primary outcome was mortality. The secondary outcomes were the ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen (PaO 2 /FIO 2), total positive end expiratory pressure (PEEP), plateau pressure (Pplat), days free of ventilator at day 28, barotrauma and ICU-acquired weakness. Results We included 6 RCTs (n = 1557). Compared with placebo or usual treatment, NMBAs were associated with lower 21 to 28-day mortality (RR 0.72, 95% CI 0.53-0.97, I2 = 59%). NMBAs significantly improved oxygenation (Pao2:Fio2 ratios) at 48 hours (MD 27.26 mm Hg, 95% CI 1.67, 52.84, I2 = 92%) and reduced the incidence of barotrauma (RR 0.55, 95% CI 0.35, 0.85, I2 = 0). However, NMBAs had no effect on oxygenation (Pao2:Fio2 ratios) (MD 18.41 mm Hg, 95% CI-0.33, 37.14, I2 = 72%) at 24 hours. We also found NMBAs did not affect total PEEP, plateau pressure, days free of ventilation at day 28 and ICU-acquired weakness.