This study aims at developing the mHealth application (YoungAsthma) and evaluating the effectiveness of YoungAsthma app on the mean score of the asthma control test and self-efficacy scale in adolescents with asthma. This study is a self-efficacy theory-based, 4-week, randomized parallel group study. Participants will be randomized to either the intervention or control group in a 1:1 ratio. Adolescents will be randomly allocated to intervention (YoungAsthma which is a user-focused mHealth app) or control group (Usual care). The study protocol is conducted in accord with the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT 2013 Statement) (Chan et al., 2013), the RCT is perform by the Consolidated Standards of Reporting Trials (CONSORT) (Moher et al., 2010) and the mHealth app is identified according to the mERA guideline (Agarwal et al., 2016).