BACKGROUND: Mobile health interventions are being widely tried because of their attractive advantages. However, there is not enough evidence for its effectiveness. OBJECTIVE: This study aimed to evaluate the effects of mobile app-based stress management intervention (mSMI) on highly stressed workers. METHODS: A sample of 82 white-collar workers with elevated symptoms of perceived stress (Perceived Stress Scale10 >= 22) were randomly assigned to the intervention or control group. ThemSMIconsisted of three modules: self-management including a work diary, counseling based on cognitive behavioral therapy and interventions focused on music, meditation, relaxation and image healings. Self-report data were collected at the baseline and post-intervention. Study outcomes analyzed perceived stress, anxiety, depression, and work engagement. Data were assessed using analysis of covariance with covariates. RESULTS: There was significantly reduced perceived stress from baseline to 6 weeks in mSMI (t = 5.788, p < 0.001) and control group (t = 3.184, p = 0.003). After adjusting for covariates, the between-group difference in the perceived stress was significantly different (F = 4.051, p = 0.048); however, the effect size was small. There was no significant intervention effect on anxiety, depression, and work engagement. The process evaluation indicated that most participants (85.3%) were satisfied with the intervention and their mental health benefited. CONCLUSION: This study found that mobile health intervention facilitated perceived stress management for highly stressed workers. Further studies should address job-related outcomes and mental health symptoms in workers by applying the latest information technology and addressing the limitations of mobile interventions.