Study Design: Retrospective Cohort Study. Objectives: Unilateral biportal endoscopy (UBE) provides a minimally invasive option for treating lumbar spinal stenosis, enabling faster recovery but requiring surgical precision. This study aims to establish a learning curve model for UBE in central lumbar spinal stenosis, focusing on surgical duration and neuromonitoring data. Methods: Data were collected from a senior orthopedic spine surgeon’s cases involving lumbar spinal stenosis. Neuromonitoring was performed during UBE, recording each dural and root irritation as a risk. Surgical details, including operative time (from first incision to final suture) and neuromonitoring events, were documented. The RA-CUSUM method in Python was used to evaluate proficiency, adjusting for procedure time. Results: Seventy-eight patients with central lumbar spinal stenosis were included. RA-CUSUM analysis, integrating neuromonitoring and surgical time, indicated significant proficiency gains by the 16th case, with reductions in procedural time and neural irritations. CUSUM analysis based solely on operative time showed stabilization and efficiency improvements by the 35th case. Conclusion: Proficiency in UBE surgery is generally achieved by the 16th case regarding neuromonitoring management and by the 35th case regarding time efficiency. These findings are valuable for surgeons transitioning to UBE, although the results may not fully generalize to those without prior surgical experience. Continued research and structured training are essential to optimize UBE outcomes.