Objective To explore the function and molecular mechanisms of matrix metalloproteinase 19 （MMP-19） in colorectal cancer （CRC） and liver metastasis of CRC （CRLM）. Methods This study comprehensively analyzed transcriptomic data， single-cell data， and clinical information of CRC and CRLM patients retrieved from public databases， namely The Cancer Genome Atlas （TCGA） and Gene Expression Omnibus （GEO）. RNA sequencing analysis was carried out to identify biological functions associated with MMP-19 expression. The differential expression of MMP-19 between primary lesions and liver metastatic lesions was evaluated using quantitative real-time polymerase chain reaction （qRT-PCR）， Western blotting， and immunohistochemistry. In vitro functional assays were performed to validate the impact of MMP-19 on the proliferation， invasion， and migration of colorectal cancer cells. Results MMP-19 was highly expressed in CRC tissues and was significantly correlated with poor prognosis in both CRC and CRLM patients. Sequencing results and functional enrichment analysis demonstrated that MMP-19 is involved in epithelial-mesenchymal transition， amino acid and protein transport， cell proliferation， extracellular matrix organization， and the mitogen-activated protein kinase （MAPK） signaling pathway. Single-cell analysis revealed that the expression of MMP-19 in macrophages and dendritic cells was higher in both CRC primary tumors and liver metastases compared to normal tissues. In vitro experiments confirmed that MMP-19 enhances the proliferation， invasion， and migration capabilities of colorectal cancer cells. Conclusion MMP-19 has been shown to play a crucial role in promoting the development and progression of CRC. It increases the risk of postoperative recurrence and liver metastasis through inducing epithelial-mesenchymal transition and remodeling the immune microenvironment. Given these findings， MMP-19 emerges as a promising novel target for the diagnosis and treatment of both CRC and CRLM.