As newly found non‐coding RNAs, circular RNAs (circRNAs) are involved in multiple biological processes. Emerging evidence has illustrated the pivotal roles of circRNAs in various human cancers. However, the function of circFAT1 in hepatocellular carcinoma (HCC) remains largely unclear. In the present study, we found that circFAT1 expression is up‐regulated in HCC tissues and cells. In addition, circFAT1 level is positively correlated with TNM stage and tumour size. To further explore the function of circFAT1 in HCC, in vitro and in vivo experiments were performed. The results show that circFAT1 inhibition reduces the proliferation and invasion of HCC cells and tumorigenesis in vivo, whereas REEP3 overexpression reverses these processes. In conclusion, circFAT1 sponges miR‐30a‐5p to regulate the expression of REEP3, thus promoting hepatocarcinogenesis. New HCC diagnosis or treatment strategies may be developed from circFAT1 as a target.