Presurgical orthodontic treatment has long been known as a prerequisite in the traditional orthognathic approach. However, achieving ideal decompensation is very difficult even in the presurgical orthodontic period. For minimization of this problem, the surgery-first orthognathic concept has been introduced. The authors hypothesized that this treatment modality will be feasible for skeletal class III dentofacial deformity patients. In this study, the authors tried to compare the traditional and surgery-first approaches regarding long-term outcomes in terms of stability, based on large-scale data. The patients included in this study had skeletal class III dentofacial deformities, and all underwent, and completed, orthognathic surgery between December 2007 and December 2015. The inclusion criteria were based on presurgical simulation on the dental model, and the authors predicted the potential of the surgery-first approach by this preoperative simulation model. Patients with cleft-related syndromes, those who underwent orthognathic surgeries due to facial asymmetry or class II deformity were excluded from the study. In total, 104 class III patients were enrolled in the surgery-first group and 51 class III patients in the traditional orthodontic-first group. Satisfactory results were achieved in all 155 patients with dentofacial deformity in this study. Overall, the analysis revealed that anteroposterior skeletal long-term stability in the surgery-first approach was not different, statistically or otherwise, from that in the orthodontic-first approach. Anteroposterior skeletal stability was maintained well in the surgery-first approach. In conclusion, surgery-first approach without presurgical orthodontic treatment can achieve similar results of long-term anteroposterior stability in correcting dentofacial deformities as the orthodontic treatment-first approach.