The utility of the mucolytic dornase alfa in bronchiolitis has not been established, yet it is commonly used. The objective of this study was to compare outcomes of dornase alfa to standard of care treatments for bronchiolitis in mechanically ventilated pediatric patients. This was a retrospective, cohort study conducted at a single-center children's hospital evaluating pediatric patients with a diagnosis of bronchiolitis that required hospitalization and mechanical ventilation from January 1, 2010 to December 31, 2019. The primary outcome evaluated was length of time on mechanical ventilation. Secondary outcomes were pediatric intensive care unit (PICU) length of stay and length of hospitalization. Multiple linear regressions were used to assess the association of age, oxygen saturation index (OSI), positive endexpiratory pressure values, blood pH levels, respiratory syncytial virus status, and the use of other mucolytics, bronchodilator therapy, or chest physiotherapy treatment. Seventy-two patients were included in the study with 41 patients who were treated with dornase alfa. The patients who received dornase alfa had an average of 33.04 h longer on mechanical ventilation than those who did not (p = 0.0487). On average, they also had longer PICU and hospital stays by 2.05 days (p = 0.053) and 2.74 days (p = 0.02), respectively. In this study, pediatric patients who received dornase alfa had higher baseline OSI measurements than those who received standard of care, which impacted the primary outcome of time on mechanical ventilation and secondary outcome of time in the PICU. However, OSI, or any other variable, did not significantly affect results for the other secondary outcome of length of hospitalization. This study supports existing evidence that dornase alfa is not beneficial for bronchiolitis in pediatric patients, even in severe cases. Further prospective, randomized controlled trials are necessary to validate these outcomes.