Objective <p>This study examined oxidative stress (OS) markers in acute relapse schizophrenia, assessed the impact of electroconvulsive therapy (ECT), and explored correlations with clinical improvement.</p> Methods <p>110 Han Chinese patients and 55 healthy controls were enrolled. All enrolled patients had multi-episode schizophrenia with a mean illness duration of 11.15 ± 9.11 years. Patients received 8–12 bilateral ECT sessions plus antipsychotics. Serum levels of GSH-Px, MnSOD, CuZnSOD, and CAT were measured before and after ECT. Symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS).</p> Results <p>At baseline, schizophrenia patients showed significantly lower serum levels of GSH-Px, MnSOD, and CAT, while the MnSOD/CuZnSOD ratio was decreased, CuZnSOD levels showed a non‑significant trend as compared to healthy controls. GSH-Px levels were negatively correlated with the PANSS positive subscale scores (<i>p</i> = 0.007). Following ECT, all PANSS scores significantly decreased (all <i>p</i> &lt; 0.001). Serum levels of GSH-Px, TSOD, CuZnSOD, and CAT increased significantly, while MnSOD levels and the MnSOD/CuZnSOD ratio significantly decreased (all <i>p</i> &lt; 0.01). In responders, changes to OS markers were significant (all <i>p</i> &lt; 0.01). Increases in GSH-Px levels were positively correlated to reductions in the PANSS total score (Bonferroni corrected <i>p</i> = 0.024) and general subscale scores (Bonferroni corrected <i>p</i> = 0.008). Multivariate logistic regression analysis identified the baseline GSH-Px level as an independent potential indicator of clinical improvement (<i>p</i> = 0.001).</p> Conclusion <p>Acute relapse schizophrenia shows significant redox imbalance. ECT in combination with antipsychotics modulates antioxidant enzymes, and GSH-Px dynamics correlate with symptom improvement, suggesting its potential as a predictive and monitoring biomarker for ECT outcomes.</p> Clinical trial <p>Not applicable.</p>