Background: Previous studies have demonstrated that vacations help workers recover from occupational stress, but this effect typically fades within 2 weeks of returning to work. To proactively reduce occupational stress, regular engagement in recreational activities is vital. During vacations, workers intuitively engage in recovery behaviors. The gamified smartphone application (app), Holidaily, was developed to encourage workers to engage in recreational activities during and beyond their vacation and integrate them into daily working life. To date, evidence is scarce on whether vacation-related recovery can be enhanced with a gamified app and whether the user experience (UX) of an app can significantly impact health. Objectives: This study examined whether UX of a gamified app predicts users’ improvement in recovery from work-related stress. Methods: Data were gathered from 171 Holidaily users, levels of recovery assessed 2 weeks pre- and post-vacation. The relationship between UX and change in recovery were examined by regression analysis. Results: Holidaily users experienced substantially prolonged recovery, where the apps UX uniquely predicted recovery. This improvement could not be explained by sociodemographic or work-related variables, vacation length or pre-vacation level of depression. Conclusions: Our findings support prior research demonstrating the effectiveness of apps promoting psychological health and are the first to reveal an app’s effectiveness augmenting recovery from work-related stress. Findings also highlight that the health effectiveness of an app is dependent on its UX.