Circular RNAs are abundant and conserved endogenous RNAs that are formed by exon skipping or back‑splicing events and occur in all forms of life. They have been proven to exhibit tissue‑ or cell‑type specificity and to be able to regulate cell behavior through multiple pathways. In cancer research, numerous studies have indicated that circular RNAs serve as potential biomarkers and therapeutic targets. Furthermore, differential expression of certain circular RNAs clearly predicts the clinical outcomes of cancer patients. Circular RNAs regulate carcinogenesis and cancer progression by acting as a microRNA sponge, coding for proteins and interacting with proteins. The present review mainly focuses on the recent literature regarding the role of circular RNAs in cancer, which may suggest novel strategies for cancer prognosis, diagnosis and clinical treatment.