Prospectively updated long-term data and retrospective case series analysis. To report the long-term results of selective anterior instrumented thoracolumbar (ThL) fusion in adolescent idiopathic scoliosis (AIS). The results of anterior selective fusion in AIS have been reported up to 2 and 5 years follow-up. However, there is a lack of evidence of long-term results of this surgical approach. Forty-two consecutive patients with main thoracolumbar/lumbar AIS who had undergone surgery for a selective anterior ThL instrumented fusion with more than 12 years of follow-up met inclusion criteria. Preoperative, postoperative (1-yr), and final updated radiographic parameters were recorded. Final ODI and SRS-22 questionnaires were evaluated. Thirty-five patients were finally recruited (5 were lost and 2 refused). The mean age at surgery was 16.6 years. The mean final follow-up was 17.3 years (12-24 yr).The ThL preoperative Cobb was 49.5° ± 9, obtaining a postoperative correction of 79%±13 and final correction of 72% ± 18. The preoperative thoracic curve (31.4° ± 14.2) obtained a spontaneous postoperative correction to 18.4° ± 11.9, maintained at final follow-up (17.8° ± 10.8). Apical vertebral rotation improved from 25.8° ± 7.8 to 9.2° ± 5.5 and finally to 8° ± 5.2 (P = 0.001). Sagittal parameters (T5-T12 = 27.2° and L1-S1=56.9°) did not change significantly postoperatively nor by final follow-up. Coronal balance improved from 2.4 cm to 1.6 cm postoperatively and 0.8 cm at final follow-up (P = 0.006). The disc angulation below the last instrumented vertebra improved with follow-up from 7.6° to 5.7° (P = 0.012).There were no revision surgeries or infections. One patient showed a symptomatic lower disc degeneration requiring lumbar pain surgery. Final SRS-22 global score was 4.3/5. The final ODI scored 6/100. In the long term, selective anterior thoracolumbar instrumentation with a single solid rod in AIS maintained good corrections on the three planes with no major complications or infections, no revision surgeries, and with satisfactory final functional and clinical outcomes. 4.