Many circular RNAs (circRNAs) are reported to be abnormally expressed during the progression of various tumors, and these circRNAs can be used as anti-tumor targets. Therefore, it is important to identify circRNAs that can be used effectively for the clinical diagnosis and treatment of colorectal cancer (CRC). Here, we report that hsa_Circ_0000826 (Circ_0000826), a significantly underexpressed circRNA in CRC tissues, is associated with a poor prognosis in patients. The silencing of Circ_0000826 promoted the proliferation of CRC cells. Conversely, the overexpression of Circ_0000826 restricted cell proliferation both in vitro and in vivo. Furthermore, Circ_0000826 could target AU-rich element RNA-binding protein 1 (AUF1). AUF1, known as heterogeneous nuclear ribonucleoprotein D (hnRNP D), could bind to the c-Myc 3'-UTR and promote c-Myc expression. When Circ_0000826 binds to AUF1, Circ_0000826 competitively inhibits the binding of AUF1 to the c-Myc 3'-UTR, which inhibits the c-Myc expression and cell proliferation. These results provide novel insights into the functional mechanism of action of Circ_0000826 in CRC progression and indicate its potential use as a therapeutic target in CRC.