Activation of hepatic progenitor cells (HPCs) is commonly observed in chronic liver disease and Wnt/β‐catenin signaling plays a crucial role in the expansion of HPCs. However, the molecular mechanisms that regulate the activation of Wnt/β‐catenin signaling in the liver, especially in HPCs, remain largely elusive. Here, we reported that ectopic expression of Smad6 suppressed the proliferation and self‐renewal of WB‐F344 cells, a HPC cell line. Mechanistically, we found that Smad6 inhibited Wnt/β‐catenin signaling through promoting the interaction of C‐terminal binding protein (CtBP) with β‐catenin/T‐cell factor (TCF) complex to inhibit β‐catenin mediated transcriptional activation in WB‐F344 cells. We used siRNA targeting β‐catenin to demonstrate that Wnt/β‐catenin signaling was required for the proliferation and self‐renewal of HPCs. Taken together, these results suggest that Smad6 is a regulatory molecule which regulates the proliferation, self‐renewal and Wnt/β‐catenin signaling in HPCs. J. Cell. Physiol. 229: 651–660, 2014. © 2013 Wiley Periodicals, Inc.