The success of targeted drug therapy for cancer patients has attracted extensive attention from academia and society. However, the rapid development of acquired drug resistance is becoming a major challenge. Autophagy, as an essential homeostatic and catabolic process, is crucial for the degradation or recycling of proteins and cellular components. Autophagy has a crucial role in several cellular functions and its dysregulation is associated with tumorigenesis, tumor–stroma interactions, and resistance to cancer therapy. A growing body of evidence shows that in multiple types of cancer, autophagy is also a key regulator in the tumor microenvironment and the cellular drug response. However, our understanding of the process of autophagy remains incompletely. In this review, we identify the role of autophagy and describe recent advances in the identification of the mechanism by which autophagy is implicated in drug resistance, with a focus on the mode of action, and validation as potential therapeutics.