Colon cancer is one of the deadliest cancers worldwide; abnormal microRNA expression is common during colon cancer development. The aim of the present study was to elucidate the role played by miR-185 in this context. We used quantitative real-time PCR (qRT-PCR) to measure miR-185 expression levels in colon cancer cell lines. The effects of miR-185 on colon cancer cell proliferation and invasion were assessed using the MTT, colony-forming, wound-healing, and transwell assays. A luciferase activity assay was used to confirm the target of miR-185. Our data showed that miR-185 was significantly down-regulated in colon cancer cells and colonic cancer tissues compared with NCM460 normal colonic epithelial cells and adjacent normal tissues. A functional analysis revealed that ectopic expression of miR-185 significantly inhibited colon cancer cell proliferation, colony formation, migration, and invasion. In addition, western blot, qRT-PCR, and luciferase assays confirmed in colon cancer cells that Wnt1 was a downstream target of miR-185, in turn suppressing β-catenin-mediated signaling. In conclusion, we found that miR-185 inhibits colon cancer cell proliferation and invasion by targeting Wnt1, and that it serves as a tumor suppressor, indicating that the modulation of miR-185 levels may potentially be therapeutic in colon cancer patients.