Objective To systematically evaluate the efficiency of prewarming i-gel laryngeal mask for mechanical ventilation by meta-analysis and trial sequential analysis. Design Systematic review and meta-analysis. Data sources Cochrane library, Web of Science, Ovid Medline and PubMed were searched from their inception to 31 August 2020. Only articles published in English language were considered. Methods Randomised controlled trials (RCTs) comparing the efficiency of prewarming i-gel laryngeal mask versus keeping it at room temperature for mechanical ventilation were included. Primary outcome was sealing pressure immediately after successful ventilation. Secondary outcomes were the first-attempt insertion success rate and the incidence of postoperative pharyngeal pain. Two authors independently selected studies. Quality analysis was performed using the modified Jadad Scale. Trial sequential analysis (TSA) was used to control risk of random errors. Sensitivity analysis was done to assess the effect of a single study on the pooled estimates. Publication bias was assessed by funnel plots and Egger's regression test. Results Four RCTs comprising 374 patients were included. The results of meta-analysis showed that compared with the control group, prewarming i-gel laryngeal mask provides a higher sealing pressure immediately after successful ventilation (mean difference 2.19 cm H2O; 95% CI (1.17 to 3.21); p<0.0001; high quality), with firm evidence from TSA and lower publication bias (p=0.7372). No significant difference was observed in the first-attempt insertion success rate (relative ratio (RR) 1.06; 95% CI (1.00 to 1.12); p=0.07; high quality) with lower publication bias (p=0.1378). The TSA indicating further trials are required. No significant difference was assessed in the incidence of postoperative pharyngeal pain (RR 1.0; 95% CI (0.14 to 6.90); p=1.0; high quality). Conclusion Prewarming i-gel laryngeal mask provides higher sealing pressure compared with keeping it at room temperature. But prewarming i-gel laryngeal mask did not increase the first-attempt insertion success rate, nor did it decrease the incidence of postoperative pharyngeal pain.