© 2015 ARS-AAOA, LLC.Background: In this prospective, multicenter, randomized, controlled, double-blind study, we investigated the impact of a mobile patient engagement application on health outcomes and quality of life in allergic rhinitis (AR) and asthma patients. Methods: In total, 327 patients with diagnoses of persistent AR or mild-to-severe persistent asthma were randomized into 2 intervention groups and 2 control groups upon their admission at outpatient clinics. The intervention groups (POPET-AR and POPET-Asthma) received a mobile phone application ("physician on call patient engagement trial" [POPET]), enabling them to communicate with their physician, and record their health status and medication compliance. The AR groups completed the Rhinitis Quality of Life Questionnaire (RQLQ) at initiation and at the first month of the study. The asthma groups completed the Asthma Control Test (ACT) at initiation and at the third month of the study. Results: The POPET-AR group showed better clinical improvement than the control group in terms of the overall RQLQ score as well in measures of general problems, activity, symptoms other than nose/eye, and emotion domains (p < 0.05). In the POPET-Asthma group, more patients (49%) achieved a well-controlled asthma score (ACT > 19) compared with the control group (27%); this was statistically significant (p < 0.05). Conclusion: Use of a mobile engagement platform, such as POPET, can have a significant impact on health outcomes and quality of life in both AR and asthma, potentially decreasing the number of hospital admissions, repeat doctor visits, and losses in productivity. Improvements were seen in domains related to activity, productivity, perception of disease, and emotion.