Background: Anatomical variations of the nasal cavity and paranasal sinuses are common in the pediatric population and may influence sinus ventilation, susceptibility to infection, and craniofacial development. Cone-beam computed tomography (CBCT), frequently used for dental purposes, offers an opportunity to detect these incidental variations in growing individuals. Method: This retrospective study evaluated CBCT scans of 128 patients under 16 years of age, obtained between 2017 and 2025. Images fully capturing the sinonasal region were analyzed for variations of the nasal septum, conchae, ethmoid, maxillary, frontal, and sphenoid sinuses. Variations were recorded as present or absent, and prevalence rates were analyzed by age and sex. Results: The study sample included 68 girls (53.1%) and 60 boys (46.9%), with a mean age of 12.27 ± 2.26 years. The most common bilateral variations were accessory maxillary ostium (39.8%), agger nasi cells (37.5%), and middle concha bullosa (29.6%). For single-structure variations, nasal septal spur (43.2%), nasal septum deviation (38.3%) were most frequently observed. No statistically significant sex differences were found in the distribution of variations (p > 0.05). Conclusion: This study demonstrated that incidental anatomical variations of the nasal cavity and paranasal sinuses are frequent in the pediatric population. Many of these variations may predispose to sinonasal pathology or influence dentomaxillofacial development. Awareness of such findings on CBCT scans is essential for accurate diagnosis, treatment planning, and surgical risk assessment, particularly in dental and maxillofacial practice.