WNT5B is a member of the WNT family that has been reported to be overexpressed in a variety of cancer cell lines and tissues, including colorectal cancer (CRC). However, the potential roles of WNT5B in tumorigenesis have not been reported. In the present study, the WNT5B gene was transfected into CRC cells and generated a COLO 205 cell line with stable overexpression of WNT5B. MTT, wound healing and Transwell assays showed that overexpression of WNT5B significantly increased cell proliferation, migration and invasion capacities of the COLO 205 cells in vitro. Meanwhile, western blotting demonstrated that cells with stable expression of WNT5B showed increased protein expression levels and activities of matrix metalloproteinase (MMP) 2 and MMP 9. In addition, we also observed activation of the WNT/JNK signaling pathway in WNT5B-overexpressing cells. Subsequently, c-jun NH2-terminal kinase (JNK) was knocked down by RNA interference in the WNT5B-overexpressing COLO 205 cells. Knockdown of JNK significantly reduced the migratory capacity of the COLO 205 cells and decreased protein expression levels and activities of MMP 2 and 9 in vitro. In conclusion, our findings suggest that WNT5B may play an important role in the tumorigenesis of CRC.