Aim: Transcutaneous electrical cranial-auricular acupoint stimulation (TECAS) is a novel non-invasive therapy that stimulates acupoints innervated by the trigeminal and auricular vagus nerves. An assessor-blinded, randomized, noninferiority trial was designed to compare the efficacy of TECAS and escitalopram in mild-to-moderate major depressive disorder.Methods: 468 participants received two TECAS sessions per day at home (n = 233) or approximately 10-13 mg/day escitalopram (n = 235) for 8 weeks plus 4-week follow-up. The primary outcome was clinical response, defined as a baseline-to-endpoint ≥50% reduction in Montgomery-Åsberg Depression Rating Scale (MADRS) score. Secondary outcomes included remission rate, changes in the severity of depression, anxiety, sleep and life quality. Results:The response rate was 66.4% on TECAS and 63.2% on escitalopram with a 3.2% difference (95% confidence interval [CI], À5.9% to 12.9%) in intention-to-treat analysis, and 68.5% versus 66.2% with a 2.3% difference (95% CI, À6.9% to 11.4%) in per-protocol analysis. The lower limit of 95% CI of the differences fell within the prespecified non-inferiority margin of À10% (P ≤ 0.004 for non-inferiority). Most secondary outcomes did not differ between the two groups. TECAS-treated participants who experienced psychological trauma displayed a markedly greater response than those without traumatic experience (81.3% vs 62.1%, P = 0.013). TECAS caused much fewer adverse events than escitalopram.Conclusions: TECAS was comparable to escitalopram in improving depression and related symptoms, with high acceptability, better safety profile, and particular efficacy in reducing trauma-associated depression. It could serve an effective portable therapy for mild-to-moderate depression.