Background <p>The bronchial blocker (BB) is one of the commonly used airway management devices for achieving lung isolation and one-lung ventilation in thoracic surgery. With its widespread application, various complications have been increasingly reported, but potentially devastating complications such as intra-airway BB balloon detachment are rarely reported. We present a case of balloon detachment that occurred during BB removal.</p> Case presentation <p>A 76-year-old male patient underwent resection of a right middle lobe pulmonary nodule, a procedure in which lung isolation and single-lung ventilation were successfully achieved using a BB. Upon withdrawal of the blocker postoperatively, the balloon was discovered to have detached. The detached balloon was subsequently retrieved using tissue biopsy forceps under fiberoptic bronchoscopic guidance. This incident resulted in no serious sequelae, and the patient recovered and was discharged.</p> Conclusion <p>Balloon detachment from the BB is a serious complication. Strict preoperative assessment, thorough equipment inspection and sustained intraoperative vigilance can reduce its incidence. The most critical preventive measure is to position the BB under direct vision using a fiberoptic bronchoscope. Furthermore, the use of continuously visible airway management equipment may enhance overall clinical safety.</p>