Purpose: To assess the effect of low dose corticosteroids on outcomes in adults with septic shock. Methods: We systematically reviewed randomised clinical trials (RCTs) comparing low-dose corticosteroids to placebo in adults with septic shock. Trial selection, data abstraction and risk of bias assessment were performed in duplicate. The primary outcome was short-term mortality. Secondary and tertiary outcomes included longer-term mortality, adverse events, quality of life, and duration of shock, mechanical ventilation and ICU stay. Results: There were 22 RCTs, including 7297 participants, providing data on short-term mortality. In two low risk of bias trials, the relative risk (RR) of short-term mortality with corticosteroid versus placebo was 0.98 [95% confidence interval (CI) 0.89–1.08, p = 0.71]. Sensitivity analysis including all trials was similar (RR 0.96; 95% CI 0.91–1.02, p = 0.21) as was analysis of longer-term mortality (RR 0.96; 95% CI 0.90–1.02, p = 0.18). In low risk of bias trials, the risk of experiencing any adverse event was higher with corticosteroids; however, there was substantial heterogeneity (RR 1.66; 95% CI 1.03–2.70, p = 0.04, I ² = 78%). No trials reported quality of life outcomes. Duration of shock [mean difference (MD) −1.52 days; 95% CI −1.71 to −1.32, p < 0.0001], duration of mechanical ventilation (MD −1.38 days; 95% CI −1.96 to −0.80, p < 0.0001), and ICU stay (MD −0.75 days; 95% CI −1.34 to −0.17, p = 0.01) were shorter with corticosteroids versus placebo. Conclusions: In adults with septic shock treated with low dose corticosteroids, short- and longer-term mortality are unaffected, adverse events increase, but duration of shock, mechanical ventilation and ICU stay are reduced. PROSPERO registration no. CRD42017084037.