Stepped care is an increasingly popular treatment model for common mental health disorders, given the large discrepancy between the demand and supply of healthcare service available. In this review, we aim to compare the efficacy and cost-effectiveness of stepped care prevention and treatment with care-as-usual (CAU) or waiting-list control for depressive and/or anxiety disorders. 5 databases were utilized from its earliest available records up until April 2015. 10 randomized controlled trials were included in this review, of which 6 examined stepped care prevention and 4 examined stepped care treatment, specifically including ones regarding depressive and/or anxiety disorders. Only trials with self-help as a treatment component were included. Results showed stepped care treatment revealed a significantly better performance than CAU in reducing anxiety symptoms, and the treatment response rate of anxiety disorders was significantly higher in stepped care treatment than in CAU. No significant difference was found between stepped care prevention/treatment and CAU in preventing anxiety and/or depressive disorders and improving depressive symptoms. In conclusion, stepped care model appeared to be better than CAU in treating anxiety disorders. The model has the potential to reduce the burden on existing resources in mental health and increase the reach and availability of service.