Colorectal cancer (CRC) is considered as one of the leading types of cancer in the world. CD133, as a cancer stem cell marker, has a pivotal role in the development of drug resistance, migration, and stemness properties of CRC cells. This study designed to check the combined effect of CD133siRNA and Oxaliplatin on proliferation, migration, apoptosis, and stemness properties of CRC cells in HT-29 cell line.MTT assay was performed to define the combined effect of CD133siRNA and Oxaliplatin on the viability of HT-29 cells. In order to figure out the effect of this combination therapy on CD133 expression at the gene and protein level, qRT-PCR and western blot were exploited, respectively. The ability of cell migration was tested by wound healing assay as well. Also, colony formation and sphere formation were conducted to assess the stemness properties in the combination group. Flow cytometry was conducted to investigate the apoptosis, cell cycle, and surface expression of CD133 in different groups. Finally, the expression of migration-, and stemness-associated genes were measured by qRT-PCR. We indicated that silencing of CD133 reduces the migration and stemness properties of colorectal cancerous cells. This suppression makes HT-29 cells more sensitive to Oxaliplatin and reduces the effective dose of this chemical drug. Therefore, the suppression of CD133 in combination with Oxaliplatin treatment might be a promising therapeutic approach in the treatment of colorectal cancer.