Current anticancer nanocarriers are still constrained by a disparity between their various functionalities and biocompatibility. Drug combinations delivered via cell-specific nanocarriers have the potential to improve therapeutic efficacy. Herein, we prepared a ROS-responsive CuO nanoparticle drug delivery system for treating breast cancer loaded with 5-Fluorouracil (5-FU) and paclitaxel (PTX), encased in a layer of PHBV/PDA and embellished with folate to yield 5-FU@PTX-CuO@PHBV@PDA/FA NPs. Excellent monodispersity, size stability, and biocompatibility were displayed by the resulting nanoplatform with a diameter of about 186.3 ± 7.2 nm. Synthesized nanoplatform was studied in NIH 3T3 and MCF-7 cells to determine their antitumor mechanism. Invitro pH-dependent drug release rate, drug encapsulation, loading efficiency, and hemocompatibility were all quantified via Ultraviolet–visible spectroscopy. Half-maximal inhibitory concentration values for dual drug-loaded CuO@PHBV@PDA/FA NPs and free drugs combination were 12.5 and 25 μg/mL, respectively, indicating considerably stronger antitumor activity of 5-FU@PTX-CuO@PHBV@PDA/FA NPs than free drugs combination. Apoptotic cell death, mitochondrial membrane potential loss, and ROS production were also examined in vitro. In contrary, dual drug-loaded nanoparticles exhibited concentration-dependent and synergistic cytotoxicity towards MCF-7 cells. Together, these findings suggest that the 5-FU@PTX-CuO@PHBV@PDA/FA nanoplatform may help to resolve the conflict between the multifunctionality and biocompatibility of nanocarriers.