Recent studies have shown that miRNAs have potent abilities to activate gene expression by targeting promoter elements, a phenomenon known as RNA activation (RNAa). In the present study, we identified a new endogenous miR-3619-5p which was decreased in prostate cancer tissues and cells compared to corresponding normal controls. Moreover, overexpression of miR-3619-5p readily induced CDKN1A gene expression by directly targeting the putative site in the promoter. Besides, miR-3619-5p possessed considerable capacity to inhibit prostate cancer DU145 and PC3 cell growth, and downregulate several CDKN1A downstream genes, such as cyclin D1, CDK4 and CDK6. Notably, this antitumor function of miR-3619-5p was mainly achieved by stimulating CDKN1A expression.