Abstract Myeloperoxidase (MPO) promoter SNPs rs2243828 (−764T>C) and rs2333227 (G-463A) program malignant phenotypes by regulating MPO transcriptional activity. In this study, we enrolled a total of 1,175 controls and 1,078 patients with colorectal cancer with comprehensive clinical and survival information to assess whether these SNPs could affect the susceptibility and development of colorectal cancer. The MPO rs2333227 TT genotype significantly increased the risk of colorectal cancer and decreased the overall survival time of patients. Colorectal cancer cells with the rs2333227 TT genotype exhibited enhanced proliferation, migration, and invasion capacity in vitro and in vivo. Mechanistically, we found that MPO SNP rs2333227 C to T mutation altered the binding affinity of the transcription factors AP-2α to the rs2333227 mutation region, sequentially enhancing expression levels of MPO and activating further IL23A–MMP9 axis–mediated oncogenic signaling. Taken together, our findings indicate that MPO SNP rs2333227 serves as a marker of enhanced risk for development of colorectal cancer. Significance: MPO polymorphisms are a guide for high risk and poor prognosis in patients colorectal cancer. Cancer Res; 78(10); 2760–9. ©2018 AACR.