INTRODUCTION: Postoperative delirium (POD) is a common complication in elderly patients and is closely associated with delayed recovery, prolonged hospital stays, increased mortality rates and increased medical expenses. Vagus nerve stimulation, a novel technique in the field of neuroscience, has demonstrated remarkable therapeutic potential in improving neurocognitive disorders. However, its applicability in ameliorating neurocognitive dysfunctions that arise during the perioperative period remains unclear. To date, no large prospective, randomised controlled studies have explored the effects of vagus nerve stimulation on POD. METHOD AND ANALYSIS: This study is a multicentre, double-blind, parallel, randomised controlled trial. It aims to explore the preventative effects of transcutaneous auricular vagus nerve stimulation on POD in elderly patients who are scheduled for elective surgery at several medical institutions in China from 2024 to 2027. The estimated sample size is 1776, with half of the patients randomly assigned to receive prophylactic standard transauricular auricular vagus nerve stimulation during the perioperative period (allocation ratio 1:1). The primary outcome measure is the incidence of POD within 5 days after surgery. ETHICS AND DISSEMINATION: This study was approved by the Ethics Committee of Beijing Tiantan Hospital, Capital Medical University and adheres to the principles of the Declaration of Helsinki. The protocol was written in accordance with the 2013 Standard Protocol Items: Recommendations for Interventional Trials guidelines. The results of this study will be published in a peer-reviewed journal and presented at national or international conferences. TRIAL REGISTRATION NUMBER: NCT06421077.