miRNAs have been shown to play pivotal roles in the establishment and progression of colon cancer, but their underlying mechanisms are not fully understood. N-acetyltransferase NAA10 participates in many cellular processes, including tumorigenesis. Here we showed that miR-342-5p and miR-608 suppressed the tumorigenesis of colon cancer cells in vitro and in vivo by targeting NAA10 mRNA for degradation. Overexpression of miR-342-5p or miR-608 decreased NAA10 mRNA and protein levels and thereby suppressed cell proliferation, migration, and cell-cycle progression, as well as promoted apoptosis in SW480 and SW620 cells. More importantly, miR-342-5p and miR-608 significantly decreased the tumorigenic capacity of SW480 and SW620 cells in a mouse xenograft model. We also observed an inverse correlation between the expression of NAA10 and that of both miRNAs. Our results implicate miR-342-5p and miR-608 in colon cancer development and unveil the underlying mechanism of this phenomenon, which involves NAA10.