Epithelial ovarian cancer (EOC) is the leading cause of death from gynecologic malignancies. Platinum-based chemotherapy is the first-line treatment for the advanced ovarian cancer, but resistance to cisplatin remains a major obstacle to successful treatment. MicroRNAs (miRNAs) are a class of non-coding RNAs that play important roles in disease processes, including the development of drug resistance. In this study, we found miR-449a were significantly downregulated in the cisplatin-resistant ovarian cell lines SKOV3/DDP and A2780/DDP, compared with their sensitive parent line SKOV3 and A2780, respectively. The overexpression of miR-449a increased cisplatin sensitivity of SKOV3/DDP and A2780/DDP cells by inhibiting proliferation and promoting apoptosis. The luciferase assay confirmed that miR-449a functioned through suppressing NOTCH1 directly. Concordantly, BALB/c nude mice that were injected intraperitoneally with SKOV3/DDP cells transfected with miR-449a mimics exhibited enhanced cisplatin sensitivity in vivo. Taken together, these results suggest that the ectopic expression of miR-449a may be a promising therapeutic strategy for the management of cisplatin resistance in ovarian cancer.