 Three-dimensional porous carbon network (3D-C) was used as the substrate for the in situ growth of molybdenum disulfide (MoS2) through a wet chemistry method. The obtained 3D-C@MoS2 nanocomposite exhibited a porous structure, high surface area and good electrical conductivity. By using the 3D-C@MoS2 nanocomposite as a novel electrode modifier, the electrochemical oxidation peak current of bisphenol A (BPA) was greatly enhanced with a lowered background current. The improved sensitivity benefits from adsorption of BPA onto MoS2 surface, the large surface area and good conductivity of the 3D-C@MoS2 nanohybrid. By using differential pulse voltammetry (DPV), we observed a good linearity with BPA levels in the range of 0.001–10 μM, with a detection limit estimated to be 0.5 nM (S/N = 3). The 3D-C@MoS2 modified electrode could be reused for several times in spite of the accumulation of BPA, and the fabrication reproducibility is excellent. The prepared 3D-C@MoS2 modified electrode showed higher selectivity to BPA than several other phenolic compounds due to their different electrochemical oxidation potentials and the enhanced accumulation property of BPA at the 3D-C@MoS2 surface. The BPA contents in plastic product and environmental water samples were determined with the proposed method.