Background: Pediatric asthma is a prevalent disease and has a significant immunologic and inflammatory nature. In recent years, the role of vitamin D₃ in immunologic processes has been studied, and many aspects of this role have been clarified in some human diseases. Objective: The aim of this study was to evaluate the relationship among the vitamin D₃ status, Pediatric Asthma Severity Score (PASS), and inflammatory indicators of pediatric asthma. Methods: Among all of the pediatric patients with asthma and with asthma exacerbation, 100 patients were randomly enrolled in the study and subdivided into three groups according to serum levels of 25-OH vitamin D₃. The control group consisted of 100 sex- and age-matched healthy subjects. Asthma exacerbation severity was evaluated based on the PASS before starting the medical care. The count of the white blood cells, eosinophil count, and serum levels of total immunoglobulin E (IgE) plus 25-OH vitamin D₃ were measured in all the subjects. The obtained data were then compared via proper statistical tests. A p value of <0.05 was considered as statistically significant. Results: The median level of serum IgE was increased in patients with vitamin D₃ deficiency compared with other groups. There was a significant inverse correlation between serum levels of 25-OH vitamin D₃ and IgE in pediatric patients with asthma (r = -0.483, p = 0.001). Furthermore, the serum levels of 25-OH vitamin D₃ also significantly inversely correlated with the PASS (r = -0.285, p = 0.004). Conclusion: Vitamin D₃ deficiency is associated with exacerbation severity and serum IgE levels in patients with pediatric asthma; hence, it can have an important role in pediatric asthma pathogenesis, possibly through IgE.