Study Design: Retrospective study. Objective: The aim of this study was to assess long-term radiographic and clinical outcomes in Lenke 5C adolescent idiopathic scoliosis (AIS) patients after posterior selective fusion. Methods: Lenke 5C AIS patients who underwent posterior selective thoracolumbar/lumbar (TL/L) fusion in our hospital from January 2007 to January 2010 were recruited. Radiographic parameters were measured preoperatively and at the 3-month, 1-year, 2-year, 5-year, and 10-year follow-ups. The SRS-22 (Scoliosis Research Society) questionnaire was used to assess the clinical outcomes. Results: We included 37 patients who underwent posterior selective TL/L fusion surgery in our study, and the mean follow-up time was 11.26 +/- 0.85 years. The average preoperative Cobb angles of the thoracic and TL/L curves were 24.0 +/- 9.0 degrees and 45.4 +/- 6.3 degrees, respectively, which were corrected to 12.2 degrees and 12.4 degrees at the 3-month follow-up postoperatively, with correction losses of 2.2 degrees and 1.5 degrees at the 10-year follow-up. In the sagittal plane, the degree of thoracic kyphosis (TK) gradually increased over the follow-up period. The proximal junctional angle (PJA) also gradually increased from 6.7 +/- 4.6 to 13.7 +/- 5.6 during the follow-up period. For the clinical outcomes, correction surgery improved the SRS-22 scores in each domain, especially in the self-image domain. Conclusions: Posterior selective TL/L fusion can effectively correct spinal deformities, leading to stable outcomes for 10 years postoperatively. During the follow-up period, the degree of TK presented an increasing trend that remained almost constant after the 1-year follow-up. Moreover, the variation in the PJA was highly significant in the postoperative period, and it showed an increasing trend until the 2-year follow-up.