The aim of the study was to evaluate the changes in skeletal, dentoalveolar, and airway dimensions induced by the mandibular anterior repositioning appliance (MARA) in the treatment of Class II malocclusion. A group of 24 Class II patients treated with MARA was evaluated with lateral cephalograms at the start (13.8 ± 2 years) and at the end of treatment (15.7 ± 1.9 years) and compared with a matched untreated Class II group of 20 subjects selected from the archive of the AOOF Legacy. Statistical comparisons were performed with the Student’s t-test. No significant differences were observed for the sagittal airway dimensions. The MARA group showed a significant improvement of Wits (−1.4 mm; p = 0.009) and ANB angle (−0.6°; p = 0.038), a reduction in the overjet (−1.9 mm; p = 0.001), of the overbite (−1.5 mm; p = 0.005), an improvement of molar relationship (1.8 mm; p = 0.000) and a proclination of the lower incisors (2.7°; p = 0.012). During active treatment, MARA did not produce significant favorable changes in the sagittal airway dimensions in Class II subjects when compared with untreated controls. Clinically, these findings highlighted that MARA was able to provide an effective correction of Class II malocclusion with favorable dentoskeletal changes.