Asthma is one of the chronic and long-term diseases of the airways. It is characterized by reversible airflow obstruction, chest tightness, and dyspnea with decreased work of breathing. The inside airway’s walls are swollen or inflamed. The aim of this study was to determine the effectiveness of active cycle of breathing technique as an airway clearance technique in patients with asthma. The health-related quality of life and functional capacity of patients was measured using a standardized airway questionnaire (AQ20) and six-minute walk test. The study was cohort design included 38 patients (mean age 41.131±14.711) of both genders with mild to moderate asthma. Each patient received multiple sessions (3 times/week for one month) of active cycle of breathing technique. Pre and post-treatment measures were recorded for functional capacity and health-related quality of life in the form of six-minute walk test and standardized airway questionnaire. All 38 patients were stable during the study period. The health-related quality of life and functional capacity of patient significantly improved post-treatment sessions with means [205.375±93.594 for week 1, 1248.719±112.187 for week 2, 306.429±140.5554 for week 3, 337.245±134.389 for week 4], for six-minute wall test and mean difference 4.13± 2.3 SD for standardized airway questionnaire with p-value (0.00) significant upon paired t-test. It is concluded that the active cycle of breathing technique is very beneficial intervention for improving quality of life and functional capacity of patients with mild to moderate asthma. Further, investigations are required to explore efficiency of ABCT as a tool for cardio-pulmonary rehabilitation.