BACKGROUND: Lumbar disc herniation (LDH) with very high-grade migration is difficult to manage surgically because of its anatomic complexity and the risk of incomplete decompression. The unilateral biportal endoscopic (UBE) contralateral sublaminar approach is a minimally invasive technique that may be an alternative option for managing these cases. METHODS: In this multicenter retrospective study, we analyzed the clinical data of 15 patients with lumbar disc herniation with very high-grade upward or downward migration of ruptured disc fragments removed via the UBE contralateral sublaminar approach between June 2022 and June 2024. Clinical outcomes were assessed using the visual analog scale for back and leg pain, Oswestry Disability Index, and modified MacNab criteria. Radiologic outcomes were evaluated on postoperative magnetic resonance images and serial plain radiographs. RESULTS: The mean operation time was 45.3 minutes, and the average length of hospital stay was 4.1 days. The visual analog scale scores for back and leg pain improved significantly, and the Oswestry Disability Index was notably lower at the final follow-up. Postoperative magnetic resonance imaging confirmed the complete removal of migrated disc fragments in all patients, with no segmental instability observed during the follow-up. The technique allows for effective decompression with minimal bone removal, thereby preserving adjacent structures. CONCLUSIONS: This study showed the feasibility and potential benefits of the UBE contralateral sublaminar approach for lumbar disc herniation with very high-grade migration of ruptured disc fragments. Although initial outcomes are promising, further comparative studies with more patients are needed to validate its efficacy and safety.