Metastasis associated in colon cancer 1 (MACC1), a key regulator of the hepatocyte growth factor (HGF)/MET signaling pathway, has been implicated in multiple human cancers. However, little is known regarding its expression and biological function in human gallbladder cancer (GBC). In this study, we focused on the clinical significance and biological functions of MACC1 in GBC and found that MACC1 protein overexpression was frequently detected in GBC tissues. Patients with MACC1-positive tumors had worse overall survival than patients with MACC1-negative tumors. Furthermore, treatment of GBC lines with MACC1-targeting small interfering RNA oligonucleotides (MACC1-siRNA) significantly reduced the proliferation of GBC-SD and OCUG-1 cell lines and diminished both anchorage-independent growth on soft agar and cell migration. These data indicate that MACC1 acts as a putative oncogene in GBC and could be a novel diagnostic and therapeutic target for GBC.