This case report presents a novel simultaneous uniportal endoscopic decompression technique for multilevel lumbar spinal stenosis. We aim to determine the feasibility, safety profile, and preliminary clinical outcomes associated with simultaneous uniportal endoscopic "slalom" decompression performed by 2 surgeons at adjacent lumbar levels. A 66-year-old patient diagnosed with severe lumbar spinal stenosis at the L3–4 and L4–5 levels underwent bilateral decompression using a mirrored uniportal endoscopic technique performed simultaneously by 2 surgeons. An over-the-top approach was used to address neural compression. We evaluated operative time, intraoperative complications, and postoperative clinical outcomes, measured by the Oswestry Disability Index (ODI) and the visual analogue scale (VAS) for pain. Early functional recovery was also assessed. The intervention was completed in 75 minutes without intraoperative complications. The patient ambulated independently within 6 hours postoperatively and was discharged within 24 hours without adverse events. At the 6-week follow-up, the patient showed notable improvements in both VAS and ODI scores compared to baseline. Simultaneous uniportal endoscopic slalom decompression is a safe, efficient, and tissue-sparing approach for managing multilevel lumbar spinal stenosis. This technique may offer substantial benefits in selected high-risk populations. Further prospective studies with larger cohorts are warranted to validate these findings and assess long-term outcomes.