Significance Cancer stem cells (CSCs) exhibit enhanced chemo/radiotherapy resistance, and their survival following cancer treatment is believed to be responsible for tumor recurrence and metastasis. Thus, understanding the mechanisms through which CSCs survive conventional chemotherapy is essential for identification of new therapeutic strategies to prevent tumor relapse. Our findings that ovarian CSCs survive cisplatin treatment through elevated expression of polymerase η represent an opportunity to eradicate CSCs and improve the survival of ovarian cancer patients. In addition, identification of miR-93 as the regulator of polymerase η expression provides a target to increase the efficacy of cisplatin treatment.