BACKGROUND: Side effects of breast cancer treatment may persist long into survivorship, reducing quality of life (QOL) in patients with breast cancer and survivors. There is growing evidence for the use of digital health technologies, such as mobile apps, to support self-management, decrease symptom burden, and improve QOL in patients with cancer. However, an updated overview of the effects of mobile apps on QOL and well-being in patients with breast cancer and survivors is needed. OBJECTIVE: The aim of this review was to provide an overview of breast cancer-specific, mobile app-driven lifestyle or behavioral interventions in patient care through to survivorship and their impact on QOL and mental well-being. METHODS: A systematic search of PubMed, Scopus, and Web of Science was conducted to identify relevant studies. The inclusion criteria were limited to original studies involving a trial of a mobile app-driven lifestyle or behavioral intervention for patients with breast cancer or survivors and using QOL or well-being measures. The results of the studies that met the inclusion criterion were then synthesized in text and table format. The quality of the evidence was assessed with the Cochrane risk-of-bias tool. RESULTS: A total of 17 studies with the number of participants ranging from 23 to 356 met the inclusion criterion. Of the 17 reviewed studies, 7 (41%) delivered an app-only intervention, and 10 (59%) combined an app with additional supporting materials, such as SMS text messaging, telecoaching, wearables, or printed materials. Among the 17 reviewed studies, 6 (35%) focused on aiding patients with breast cancer during the active treatment phase (excluding ongoing hormone therapy), whereas the remaining 11 (65%) focused on survivorship. The majority of the studies (14/17, 82%) observed some positive effects on QOL or well-being measures. CONCLUSIONS: The results of the review indicate that mobile apps are a promising avenue for improving QOL and well-being in breast cancer care. Positive effects were observed in patients undergoing active treatment in all reviewed studies, but effects were less clear after chemotherapy and in long-term survivors. Although lifestyle and behavioral digital interventions are still being developed, and further research should still be pursued, the available data suggest that current mobile health apps aid patients with breast cancer and survivors.