With the rapid development in design and synthesis, carbon nanotubes (CNTs) are being studied for potential applications in a variety of biomedical fields, such as site-directed drug delivery, tumor-targeted imaging, and anticancer drug development. In the present study, we observed that SWCNTs could significantly induce cell death of human ovarian cancer OVCAR3 cells. More importantly, we demonstrated that SWCNTs could sensitize OVCAR3 cells to the chemotherapeutic compound paclitaxel (PTX), resulting increased cell death. Mechanistic investigations suggested that SWCNTs provoked cell death in the absence or presence of PTX mainly via apoptosis. Taken together, our results suggest that SWCNTs contribute to regulating the chemosensitivity of ovarian cancer cells to the anticancer drug. Co-exposure of SWCNTs and chemotherapeutic drugs might thus stand for a promising approach to improve the cancer treatment.