The two biologic therapies, anti-IgE (omalizumab) and anti-IL-5 antibodies (mepolizumab), are used in the treatment of severe pediatric asthma. We present here a case study of a 13-year-old girl with severe asthma who switched from omalizumab to mepolizumab therapy and achieved good control over her asthma. The patient was diagnosed with asthma at one year of age and presented with poor disease control, even while taking high doses of inhaled corticosteroids (ICS). As such, she was considered to have severe persistent asthma. At 10 years old, she began omalizumab therapy which improved asthma control. However, after two years of this therapy, she manifested frequent acute exacerbations. At 12 years old, she switched to mepolizumab and has since maintained good control of asthma. Additionally, total serum IgE levels and peripheral eosinophil counts decreased. As the underlying mechanisms of omalizumab and mepolizumab therapy are distinct, it is recommended to use either one if the other proves ineffective.