Granulosa cells (GCs) are somatic cells of ovary, the behaviors of GCs are important for ovarian function. MicroRNAs (miRNAs) are a class of endogenous 18–24 nucleotide (nt) non-coding RNAs, some of which have been shown to be important regulators of GCs function. miR-34c involved in the regulation of various biological processes and was identified to be a pro-apoptotic and anti-proliferative factor in many cell types. However, the roles of miR-34c in GCs function remain unknown. In this study, we used Annexin V-FITC and EdU assays to demonstrate that miR-34c exerted pro-apoptotic and anti-proliferative effects in porcine GCs. Dual-luciferase reporter assays, quantitative real-time PCR (qRT-PCR) and Western blotting identified Forkhead box O3a (FoxO3a) as a direct target gene of miR-34c. The overexpression of FoxO3a rescued the phenotypic change caused by miR-34c in porcine GCs. In conclusion, miR-34c regulate the function of porcine GCs by targeting FoxO3a.