Background: Asthma exacerbations lead to frequent emergency visits and hospitalizations, and are associated with high morbidity and occasionally mortality. New therapeutic strategies are needed. We sought to investigate whether the addition of high-dose inhaled budesonide to standard therapy would shorten the length of stay (LOS) in hospital of children admitted for asthma exacerbations. Methods: The study was designed as a single-center, double-blind, placebo-controlled and parallel-group trial. Children aged 7-72 months and admitted with an asthma exacerbation clinical asthma score (CAS) of between 3 and 9 were allocated to either the budesonide (n = 50) or the placebo (n = 50) group. Hospital LOS was compared between children who received 2 mg/day of budesonide versus placebo in addition to standard management of asthma exacerbation involving oxygen inhalation and β2-agonist, anticholinergic and oral corticosteroid therapy. All patients were assessed every 4 h. Children with a CAS <3, a peripheral oxygen saturation >95% and normal pulmonary function, and those with a symptom-free period of at least 4 h after salbutamol treatment were discharged. Results: Total hospital LOS was significantly shorter in the budesonide group than in the placebo group (median: 44 vs. 80 h, respectively; p = 0.01). When compared with placebo, the number of inpatients was significantly less in the budesonide group at all the assessed end points (Kaplan-Meier; p = 0.022). Additionally, nebulized budesonide was found to reduce the overall cost of treatment. Conclusion: We demonstrated that, for children hospitalized for asthma exacerbations, an additional 2 mg/day of nebulized budesonide significantly reduced hospital LOS as well as the overall cost of treatment.