Background and Objectives: Orthognathic surgery is used to restore a correct anatomical and functional relationship between the jaws, with postoperative nasal septal deviation (NSD) being a common complication of Le Fort I osteotomy (LF-IO). The aim of this study was to evaluate the occurrence of NSD after LF-IO and to identify possible risk factors. Materials and Methods: Pre- and postoperative cone beam computed tomography (CBCT) scans from 2018 to 2023 of 102 patients after LF-IO were analyzed. After categorizing the preoperative NSDs according to the Mladina classification, the next step was to measure the angle of deviation and classify the severity grades. Pre- and postoperative NSDs were compared using a paired Wilcoxon signed-rank test and postoperative changes in NSD were correlated with surgery-relevant characteristics by calculating Spearman’s correlation coefficients. Results: Postoperatively, an increase in NSD was observed in 62 cases and 35 patients showed a decrease. In both cases with an increase and a decrease in NSD, the preoperatively measured deviations showed a highly significant difference compared to postoperative NSDs (both p < 0.001). Age correlated significantly with increases in deviation (r = 0.28, p = 0.014, CI: −1.0–−0.068) and anterior maxillary displacement showed a significant correlation with a decrease in NSD (r = 0.296, p = 0.042, CI: 0.006–1.0). Gender, cranial and caudal movements of the maxilla had no influence on the results of the NSDs. Conclusions: LF-IO has an influence on NSD and can both intensify and attenuate it. In addition, the risk of an increase in nasal deviation after this surgical procedure rises with the patient’s age and decreases with anterior displacement of the maxilla.