Polycystic ovary syndrome (PCOS) is a hormonal disorder common among women of reproductive age. Although much is understood concerning the pathology of PCOS, further investigation into the influence of microribonucleic acids (miRNAs) on the proliferation of ovarian granulosa cells (GCs) is needed. This study investigated the role of specific miRNAs in ovarian dysfunction of PCOS and its effect on the proliferation of GCs. Initially, miRNA profiling was performed on the ovarian cortexes of 15 rats in which PCOS had been induced and 15 rats without PCOS (non-PCOS). This mechanical study was performed on ovarian GCs extracted from human chorionic gonadotrophin (hCG)-induced rats. Insulin was used to treat GCs to establish the PCOS cell model. Increased Equus caballus mir-9119 expression was observed and confirmed in the insulin-induced model of PCOS in GCs (GC-PCOS) as well as in the hCG-induced rats when compared to non-PCOS rats and cells. Observation and confirmation were carried out through both miRNA array and quantitative PCR. In contrast, downregulation of the nuclear factor kappa B (NFκB) p65 was observed in the PCOS cell model. Additionally, annexin V, FITC, and propidium iodide flow cytometry showed overexpression of miR-9119-induced apoptosis. In this study, we revealed that miR-9119 inhibition regulates p65 expression levels in insulin-treated GCs by binding to the 3'-untranslated of p65. Additionally, regulation of p65 expression was positively correlated with the expression of the double-stranded RNA endoribonuclease DICER. Moreover, RNA silencing/overexpression of p65 affected the functional role of miR-9119. In conclusion, GCs of PCOS, the expression of miR-9119, and targeted NFκB/p65-DICER axis are upregulated in order to maintain cell viability and prevent apoptosis, thereby promoting Anti-Müllerian hormone production in GCs. This study may provide a new understanding of the mechanism of GC dysfunction.