Severe bronchial asthma is a chronic disorder of the airways that may be accompanied by comorbid diseases. Invasive treatment, including surgery, in patients with severe asthma has limitations depending on the degree of control of the asthma. A 71-year-old woman was diagnosed with squamous cell carcinoma with high programmed death-ligand 1 (PD-L1) expression and cT3N0M1a. After 13 cycles of pembrolizumab every 3 weeks, chest computed tomography (CT) revealed a dramatic decrease in the lesion size in the left upper lobe, but the size of the lesion in the right lower lobe was significantly increased. The pathological findings of the right residual tumor by CT-guided transthoracic needle biopsy (CTNB) revealed squamous cell carcinoma with no PD-L1 expression, and right lower lobectomy was recommended. However, because the patient had frequent asthma attacks and cough, surgery was considered risky. Increased blood eosinophil count was observed, and benralizumab was administered for asthma control. The symptoms disappeared 2 days after benralizumab administration, and peak flow increased. Surgery was performed 5 days after benralizumab administration. There was a marked reduction in the eosinophil count of the surgical tissue compared with the preoperative CTNB tissue. No asthma attacks were observed during and after surgery, and the control of asthma and lung cancer was stable. Benralizumab is considered promising for the treatment of eosinophilic severe uncontrolled asthma.