Exosomes are extracellular vesicles (30-150nm) that are secreted into a various of bodily fluids and interstitial space by all types of cells. Circular RNAs (circRNAs) are a class of non-coding RNA (ncRNA) generated from the precursor mRNA (pre-mRNA) backsplicing process. Recent evidence suggests that circRNAs enriched in exosome, and play an important role in tumor microenvironment. In this review, we discuss our claim that the biogenesis of exosomal circRNAs, including the regulation mechanism of circRNAs sorting into exosomes and releasing of exosomes. Then, we elucidated the role and mechanism of exosomal circRNAs regulate EMT, cytoskeleton, angiogenesis, metabolism and inflammation, immunity and drug resistance in the tumor microenvironment. Finally, we discussed the clinical application prospects and value of exosomal circRNAs as tumor markers and therapeutic targets.