Background <p>To evaluate the correlation between the amount of maxillary advancement and soft tissue changes, and to assess the long-term skeletal stability in patients who underwent Le Fort I osteotomy as part of bimaxillary orthognathic surgery.</p> Methods <p>This retrospective cohort study included 25 patients with skeletal Class III malocclusion who underwent bimaxillary orthognathic surgery. Cephalometric measurements were obtained at three timepoints: before orthodontic treatment (T0), after postsurgical orthodontic treatment (T1), and 1–3 years post-treatment (T2), with an average follow-up period of 2.1 years. Horizontal and vertical skeletal and soft tissue changes were assessed using standardized lateral cephalometric radiographs. Repeated measures ANOVA and Pearson correlation coefficients were used for statistical analysis.</p> Results <p>The mean planned maxillary advancement was 5.48&#xa0;mm, while the actual advancement achieved was 5.32&#xa0;mm (<i>p</i> &gt; 0.05). A statistically significant correlation was found between maxillary advancement (A–VR1) and both the change in SNA angle (<i>r</i> = 0.481; <i>p</i> &lt; 0.05) and upper lip advancement (<i>r</i> = 0.319; <i>p</i> &lt; 0.05). The upper lip followed approximately 83% of the maxillary movement. The nasal tip exhibited an average elevation of 1.27&#xa0;mm, corresponding to a skeletal-to-soft tissue movement ratio of about 5:1. The mean skeletal relapse at Point A was 0.44&#xa0;mm, representing 8.2% of the total advancement, and this difference was not statistically significant.</p> Conclusions <p>Maxillary advancement performed through Le Fort I osteotomy demonstrates high precision and long-term skeletal and soft tissue stability. These findings support that Le Fort I osteotomy is a reliable, effective, and predictable surgical technique for achieving stable maxillary advancement and harmonious soft tissue adaptation over the long term.</p> Trial registration <p>Clinical trial number: not applicable.</p>