Objectives: The aim of the current study was to evaluate changes in olfactory sensitivity with Sniffin’ Sticks^® (Burghart Messtechnik, Germany) in patients undergoing palatal expansion. Methods: The study sample consisted of 20 patients enrolled from the Department of Paediatric Dentistry (0–14 years old) at the Policlinico of Rome “Tor Vergata”, according to the following inclusion criteria: negative posterior transverse interarch discrepancy ≥ 4 mm, mixed dentition phase with first permanent molars erupted and prepubertal skeletal maturation stage (CS1-2), evaluated on a lateral radiograph through the Cervical Vertebral Maturation (CVM) method. Each patient underwent a dental examination, orthopantomography and lateral cephalometric X-rays were requested, and dental impressions were taken using digital scanner. Every patient was treated with maxillary rapid expander and underwent ear, nose, and throat (ENT) assessment before and after treatment. Moreover, questionnaires before and after treatment to obtain a subjective assessment of their olfactory perception were given to all participants. Results: About odor identification, the analyses revealed an increase in mean scores of 1.28; however, this change, although slight, did not reach statistical significance (Z = −1.85; p = 0.064). In contrast, about odor discrimination, the test results indicated a statistically significant increase in the children’s scores of 3.41 (Z = −2.87; p < 0.001). Conclusions: This study supports the hypothesis that rapid maxillary expansion (RME) can improve olfactory function by enhancing nasal airway dimensions and airflow. Further studies are required to confirm these results.