To assess the effect on the retropalatal airway (RPA), retroglossal airway (RGA), and total airway (TA) volumes and cephalometrics (SNA, SNB, ANB, PP-SN, Occl-SN, N-A, A-TVL, B-TVL) after maxillary advancement orthognathic surgery in patients with unilateral cleft lip/palate (UCL/P) using cone-beam computed tomography (CBCT). The CBCT scans of 30 patients (13 males and 17 females, 17-20 years old) with UCL/P were evaluated at two time points: preoperative (T1) and postoperative (T2). The interval between T1 and T2 ranged from 9-14 weeks, except for two patients in whom the interval was 24 weeks. Intraexaminer reliability was measured with an intraclass correlation coefficient test. A paired t-test was used to compare the airway and cephalometric measurements between T1 and T2, with a P value of .05 being considered significant. From T1 to T2, significant increases were found in the volumes of RPA (from 9574 ± 4573 to 10,472 ± 4767, P = .019), RGA (from 9736 ± 5314 to 11,358 ± 6588, P = .019), and TA (from 19,121 ± 8480 to 21,750 ± 10,078, P = .002). In addition, the RGA (from 385 ± 134 to 427 ± 165, P = .020) and TA (from 730 ± 213 to 772 ± 238, P = .016) sagittal area increased significantly. For minimal cross-sectional area (MCA), only the RPA increased significantly (from 173 ± 115 to 272 ± 129, P = .002). All cephalometric changes were statistically significant between T1 and T2 except for SNB. Maxillary advancement in patients with UCL/P produces statistically significant increases in the retropalatal (volumetric and MCA), retroglossal (volumetric and sagittal), and total (volumetric and sagittal) airways based on data from CBCT imaging.