Circular RNAs (circRNAs), a novel type of non-coding RNAs (ncRNAs), are generated from pre-mRNA by covalently backsplicing of a downstream 5′ splice donor site onto an upstream 3′ splice acceptor site. Recent studies have shown that circRNAs have diverse biological functions, such as acting as a miRNA sponge to repress miRNA function, participating in splicing of target genes and translating genes into protein. These functions are involved in pathogenesis and progression of many diseases, including viral infection. In this review, we provided a brief introduction on the biological characteristics and functions of circRNAs, and summarized recent findings on the emerging roles of circRNA in viral infections, which might provide a new angle to study pathogenic characteristics and to understand the virus-host interaction mechanism.