Background: An increasing number of miRNAs were confirmed to be involved in the initiation and progression of colorectal cancer (CRC) by acting as cancer suppressor genes and oncogenes. The purpose of this study was to uncover the role of miR-449b in CRC and its underlying mechanisms. Methods: The expression profile of miR-449b in human CRC tissues and cell lines was determined using quantitative real-time polymerase chain reaction (qRT-PCR) analysis. The effect of miR-449b on CRC was assessed by CRC cell migration and invasion as determined using a transwell assay. A luciferase reporter assay was also carried out to explore the interaction between MMP2 3′UTR and miR-449b. Results: The current study revealed that the relative expression of miR-449b was decreased significantly in human CRC tissues and cell lines; meanwhile, miR-449b in metastatic CRC tissues was significantly lower than that in non-metastatic CRC tissues. We also observed that the forced miR-449b in CRC cells significantly restrained cell migration and invasion in vitro. In contrast to miR-449b, our study found that both the MMP-2 mRNA and protein levels were increased in CRC cells. MiR-449b negatively regulated MMP2 in CRC cells, and the result was corroborated by luciferase reporter assay. Most importantly, overexpression of MMP2 significantly reversed the miR-449b-mediated inhibition on the invasion and migration of CRC cells. Conclusion: Our data provided encouraging evidence that miR-449b possessed a strong inhibitory effect on CRC cell migration and invasion by negative regulation of MMP2.