We developed a novel procedure to remove or float the OPLL in the thoracic spine via a posterolateral approach. In this study, we describe this surgical procedure and report the clinical outcomes according to our surgical strategy for thoracic OPLL. For a beak-type OPLL occupying more than 50% of the spinal canal diameter, we applied this surgery. We performed total resection of the posterior elements, and cut and lifted the thoracic nerves at the levels of anterior decompression to improve the view of the OPLL and the anterolateral aspect of the dural sac with controlled bleeding. Anterior decompression was then performed postero-laterally. For other types of OPLL, posterior decompression with instrumented fusion was indicated. Between 2011 and 2022, using this surgical strategy, we operated on 44 patients with myelopathy due to thoracic OPLL. Seventeen patients underwent anterior decompression via a posterolateral approach. We prospectively analyzed clinical outcomes over a minimum 2-year follow-up period. The recovery rate, according to the Japanese Orthopedic Association score, was 65% in the anterior decompression group and 52% in the posterior decompression group. In all patients in the anterior decompression group, adequate OPLL removal or floating was achieved without any significant complications. Of the 11 patients in the anterior decompression group who had been non-ambulatory preoperatively due to severe myelopathy, all recovered ambulatory status. Anterior decompression is appropriate for patients with a large beak-type OPLL, who generally have severe neurological symptoms. Anterior decompression using our technique appears to be safe and effective.