Purpose: The aim of the study was to investigate a possible relationship between pharyngeal airway space, craniofacial variables, and dental arch form in adolescents grouped by sex. Methods: This cross-sectional study included 108 adolescents aged between 12 and 17 years. Lateral cephalometric radiographs were used to analyze sagittal craniofacial variables and the pharyngeal airway space. For evaluation of the dental arch form, we used plaster models. Statistical analysis included Student’s t‑test and Pearson’s correlation coefficient (r). Results: Maxillary length was directly proportional to upper nasopharyngeal airway dimensions in males (r = 0.312, p = 0.021) and females (r = 0.310, p = 0.022). In the female group, upper oropharyngeal measurements showed an inverse correlation with a labial inclination of the upper incisors (r = −0.415, p = 0.001), protrusion of the upper incisors (r = −0.364, p = 0.006), and soft palate thickness (r = −0.27, p = 0.043). In the male group, upper nasopharynx measurements showed an inverse correlation with soft palate thickness (r = −0.277, p = 0.042). The upper arch form appeared to be related to oropharyngeal measurements in females, while the lower arch form was related to oropharyngeal dimensions in males. Conclusion: The findings suggest that there are sex-dependent correlations of the nasopharyngeal and oropharyngeal airway space with the sagittal craniofacial morphology and the transversal dental arch form.