Bcl-2, which belongs to the Bcl-2 family, is frequently overexpressed in various types of cancer cells and contributes to drug resistance. However, the function of Bcl-2 in cisplatin resistance in human ovarian cancer cells is not fully understood. In this study, we found that the pharmacological inhibitor ABT737 or genetic knockdown of Bcl-2 increased cisplatin cytotoxicity in cisplatin-resistant ovarian cancer cells. Additionally, treatment with ABT737 or Bcl-2 siRNA increased cisplatin-induced free Ca2+ levels in the cytosol and mitochondria, which increased endoplasmic reticulum (ER)-associated and mitochondria-mediated apoptosis. In addition, ABT737 or Bcl-2 siRNA increased the ER-mitochondria contact sites induced by cisplatin in cisplatin-resistant SKOV3/DDP ovarian cancer cells. Consistently with the in vitro results, ABT737 potently synergized with cisplatin in inhibiting the growth of human ovarian cancer xenografts in nude mice. Collectively, these results indicate that pharmacological inhibitors or genetic knockdown of Bcl-2 may be a potential strategy for improving cisplatin treatment of ovarian cancer.