Objective The aim of this study was to investigate the 50% effective dose (ED50) of sugammadex for rapid recovery of transcranial electrical motor-evoked potentials (TCeMEP) by reversing profound rocuronium-induced neuromuscular block during lumbar spinal surgery. Methods American Society of Anesthesiologists (ASA) physical status I or II patients, aged from 18 to 65 year scheduled for lumbar spinal surgery under perioperative TCeMEP monitoring were enrolled. Fentanyl and propofol were intravenously injected, and tracheal intubation was performed without muscle relaxation. Then 0.9 mg/kg rocuronium was intravenously injected before incision and 10 μg/kg/min rocuronium was intraoperatively pump-injected to maintain the TOF value at 0 and the PTC value 2 at 1 or 2, respectively. When TCeMEP monitoring was required, rocuronium infusion was stopped immediately, followed by sugammadex injection intravenously at a proposed dose determined using the up-and-down sequential method. The initial dose was 1.37 mg/kg with the dose gradient ratio of 0.9. The TOF values at 3 min post-administration of sugammadex was measured and a Probit regression model was used to calculate the ED50 of sugammadex. Perioperative involuntary movement, postoperative pulmonary complications and the surgeon’s satisfaction score were recorded. Results To reverse profound rocuronium-induced neuromuscular block in lumbar spinal surgery for the rapid recovery of TCeMEP, the ED50 of sugammadex was 1.236 mg/kg with the 95% CI of 0.865-1.461 mg/kg. Reliable TCeMEP monitoring was achieved under partial reversal of neuromuscular blockade with a TOF count 3. No perioperative involuntary movement or postoperative pulmonary complications were observed, and the surgeons were very satisfied with the method. Conclusion The ED50 of sugammadex at a dose of 1.236 mg/kg enables rapid TcCeMEP monitoring by reversing profound rocuronium-induced neuromuscular block during lumbar spinal surgery.